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  • Inversion method of the key structure parameters of light screen array measurement system using genetic algorithm
    Optik (IF 1.914) Pub Date : 2020-01-27
    Rui Chen; Ding Chen; Bowen Ji; Jinping Ni

    To effectively improve the measurement accuracy of the light screen array measurement system (LSA for short) in the evaluation of continuous rapid-firing weapon, the paper presents an inversion method to obtain the key structure parameters of LSA based on genetic algorithm. First, we systematically introduce a measurement model based on the key structure parameters of the LSA. Second, we establish an objective function through the validation of the measurement results. Next, an inversion method is derived to generate many groups of structural parameters within the allowable error range. Finally, we can adopt a genetic algorithm to obtain a group of the key structural parameters which are the closest to their truth value. Through simulations and experiments, results show that the measurement model is corrected because of the key structural parameters through the inversion, and thus the accuracy of the LSA is effectively improved.

    更新日期:2020-01-27
  • Enhanced photocatalytic activity of reduced graphene oxide/SrSnO3 nanocomposite for aqueous organic pollutant degradation
    Optik (IF 1.914) Pub Date : 2020-01-27
    G. Venkatesh; M. Geerthana; S. Prabhu; R. Ramesh; K.M. Prabu

    In this present work, a novel heterostructure rGO - SrSnO3 nanocomposites with different weight percentage of reduced graphene oxide were successfully synthesised by hydrothermal method. The formation of crystalline structure, morphology, elemental composition and optical properties were characterized using Powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy dispersive X-ray analysis (EDX), and UV-Vis diffuse reflectance spectroscopy (UV DRS) and photoluminescence (PL) spectroscopy techniques. The photocatalytic activity of pure and composite materials was assessed by degradation of aqueous methylene blue dye under UV light irradiation. The highest degradation efficiency of 97% was obtained for 10 wt.% rGO - SrSnO3 composite. Enhancement in the photocatalytic activity is mainly due to the suppressed photoexcited charge carrier’s recombination rate. Moreover, the reusable and stability of the photocatalyst demonstrated after four consecutive runs of photocatalytic test.

    更新日期:2020-01-27
  • Stored energy density of electromagnetic wave in dispersive media
    Optik (IF 1.914) Pub Date : 2020-01-27
    Yuyao Dai; Yu Xuanyuan; Jiangwei Chen

    In this work, we shall demonstrate that usual expression of time-averaged stored energy density (TASED) for disperisve medium is invalid, which is mainly attributed to the fact that there exist mathematical errors in derivation of this expression. Noting connection between TASED and time-averaged Poynting vector (TAPV) and the case that TAPV of a pulse is the sum of TAPVs of its components, similarly, it is verified that TASED of a pulse in disperisve medium can be taken as the sum of TASEDs of all its components. This work may be helpful to gain a better understand of stored energy of electromagnetic wave in material media.

    更新日期:2020-01-27
  • Unifying analyses of the crystal field energy levels and EPR g factors for the trigonal Co2+ tetrahedral center in β˝-alumina
    Optik (IF 1.914) Pub Date : 2020-01-27
    Ren-Ming Peng; An-Bo Qiu; Yang Mei; Wen-Chen Zheng

    The crystal field energy levels (obtained from the optical spectra) and g factors g//, g⊥ (obtained from EPR spectra) for the Co2+ ion at the trigonal Al3+ tetrahedral site in β˝-alumina crystal are unifiedly analyzed with the full diagonalization (of energy matrix) method founded on the two-spin-orbit-parameter model (which contains the contributions from both the spin-orbit parameters of central dn ion and ligand ion via covalence effect). The results display that by applying only three adjustable parameters, the observed ten spectral data (eight crystal field energy levels and two g factors) can be rationally interpreted, confirming the availability of this full diagonalization method in the united analyses of optical and EPR data. The large impurity-generated angular distortion and hence the large trigonal distortion [which correspond to the large g-factor anisotropy and large ground state splitting ΔE(4A2)] of the Co2+ tetrahedral center in β˝-alumina are also gained. The outcomes are discussed.

    更新日期:2020-01-27
  • Surface Plasmon Induced Broadband Single-Polarization Filter Based on High Birefringence Photonic Crystal Fiber
    Optik (IF 1.914) Pub Date : 2020-01-26
    Yujun Wang; JianPing Shen; jianshe Li; Shuguang Li

    A broadband and single-polarization filter based on high birefringence photonic crystal fiber (HB-PCF) with selectively infiltrated gold wires and liquid crystal is proposed, and its filtering characteristics are studied by the full-vector finite element method (FV-FEM). Two gold wires are selectively filled on both sides of the liquid crystal core to act as two defect cores. The results show that the confinement loss of x-polarized core mode is much larger than that of y-polarized core mode in the wavelength range of 0.85-1.75 μm. The confinement losses of x- and y-polarized core modes are 99.87 dB/cm and 0.001 dB/cm at 0.88 um, 726.50 dB/cm and 0.004 dB/cm at 1.02 um, and 474.60 dB/cm and 0.046 dB/cm at 1.30 um, respectively. The bandwidth with extinction ratio less than 20 dB is 900 nm. Moreover, compared with the traditional structures, we find that our structure has higher birefringence. High birefringence helps to separate the resonant wavelengths of x- and y-polarized core modes. Therefore, the excellent properties of the proposed filter can make it widely used in sensing systems and broadband optical communication systems.

    更新日期:2020-01-26
  • Optical Transfer Function and Aberration
    Optik (IF 1.914) Pub Date : 2020-01-26
    Yu Bai; Jiaqi Chen; Qi Lu; Zhenming Zhao

    The Optical Transfer Function (OTF) is an important part of modern optics and is very useful for optical system design and evaluation. A non-Fourier transform OTF method has been recently proposed. It formulates the OTF based on the propagation of light in the frequency domain, combining the intuitiveness of geometrical optics and the accuracy of wave optics. To advance the non-Fourier transform OTF method, in this paper, we first applied it to a single convex lens and analyzed the influence of the optical pupil function on interference pairs to reveal the mechanism of how aberration affects the non-Fourier transform OTF. It was found that the aperture of the lens affects the utilization efficiency of the interference pair, and the aberration of the lens affects the utilization quality of the interference pair. Then we derived the generalized pupil function based on a two-lens system in applying this new non-Fourier transform OTF method to the analysis of complex optical systems.

    更新日期:2020-01-26
  • Strain influence on the structural properties of nitrogen and fluorine codoped TiO2
    Optik (IF 1.914) Pub Date : 2020-01-26
    Moushumi Dutta Purkayastha; Nisha Singh; Gopala Krishna Darbha; Tapas Pal Majumder

    The present work aims at outlining the role of lattice strain in modifying the structural properties of doped samples. Dual doping of TiO2 by anions nitrogen (N) and fluorine (F) was carried out by a typical hydrothermall route using inorganic precursors; ammonia solution (NH3-H2O) and ammonium fluoride (NH4F). N monodoped TiO2 (NT) showed poor crystallinity while codoping with N, F promoted the crystal growth thereby resulting in tunable particle sizes. The synergistic effects of codoping was systematically examined by changing the molar ratio of F and N. The crystalline development in the doped samples was investigated by X-ray broadening and Williamson-Hall (W-H) analysis was used to study the contribution of lattice strain to it. In comparison to NT, codoped samples showed better visible light sensitivity. Strain; even in minute amounts; induced a pronounced effect on the structural properties of the doped samples. NFT1 with the maximum strain value exhibited distinct hexagonal morphology in comparison to NFT2 and NT with lower strain values. Also, photoluminescence intensity got enhanced with increase in strain values. This study manifests the influence of strain on the dynamics of charge carriers which might affect photoactivity as well.

    更新日期:2020-01-26
  • Preparation of high laser-induced damage threshold sol-gel Nb2O5 films with different additives
    Optik (IF 1.914) Pub Date : 2020-01-25
    Wenzhe Cai; Yingtian Yang; Yongqiao Zhu; Dawei Li; Cheng Xu

    In this study, different sol-gel Nb2O5 films were prepared by using NbCl5 as precursor, and acetylacetone (ACAC), diethanolamine (DEA) and citric acid (CA) as additive, respectively. The results showed that the film with ACAC as additive presented the highest absorption and stability, corresponding to the lowest laser-induced damage threshold (LIDT) of 18.9 J/cm2, while that with CA as additive had the lowest absorption, corresponding to the highest LIDT of 24.9 J/cm2. The film prepared with DEA as additive had the smallest surface roughness, and the LIDT was 21.1 J/cm2. Moreover, although the films prepared with three different additives were all subjected to typically defect-induced damages, different types of damage features were observed. Finally, three structural evolution models of the films were proposed, accompanied by establishment of the relationship between the additives and the LIDT, which was of great significance to further understand the laser damage mechanism.

    更新日期:2020-01-26
  • Electromagnetic Simulation on Optical Performance of Thermochromic Film: Influences of Particle Size, Shape, Concentration, and Film Substrate
    Optik (IF 1.914) Pub Date : 2020-01-25
    Jianying Hu; Xiong Yu

    Thermochromic (TC) film possesses dynamic optical behaviors in response to change in environmental temperature, i.e., high solar reflectance during hot season and high solar absorptance during cold season. It has been proposed as an effective strategy to minimize energy use in buildings and improve indoor and outdoor thermal comfort. This study aims to computationally optimizing temperature-dependent optical properties of TC film in terms of particle size, shape, and volume concentration of TC pigment as well as film substrate. The computational system consists of electromagnetic simulation and Kubelka-Munk model. It has demonstrated that as particle size increases from 100 nm to 1000 nm, the total diffuse reflectance of TC film decreases from 10% to 2% below the transition temperature of TC pigment while decreases from 11% to 2% above the transition temperature. When changing particle shape from sphere to rod, the total diffuse reflectance of TC film is increased to 27% below the transition temperature and 31% above the transition temperature. Furthermore, with the substrate of aluminum, the total diffuse reflectance of TC film reaches up to 92%. Finally, as the TC pigment concentration increases from 5% to 50%, the total reflectance of TC film increases from 5% to 34%. This methodology provides guideline to tailor optical behaviors of optical film for better performance.

    更新日期:2020-01-26
  • Influence of surface microstructure on thermal damage characteristics of metal material
    Optik (IF 1.914) Pub Date : 2020-01-25
    Zhen Wang; Rongzhu Zhang; Xiaomin Yang; Yulong Ji

    A thermal damage analysis model of metal components with surface microstructure under laser irradiation is established. In order to ensure the influence law, the surface microstructure of metal component is simplified to periodic patterns. The light field and temperature distribution on the metal surface are calculated. And then the damage threshold of the component with different surface structure is calculated. The results show that the damage threshold of metal surface decreases with the increasing of the microstructure period. At the same structural period, the damage threshold of the linear structure is lower than which of the punctate structure.

    更新日期:2020-01-26
  • Comparison between UV/Vis spectrophotometry based on intelligent systems and HPLC methods for simultaneous determination of anti-diabetic drugs in binary mixture
    Optik (IF 1.914) Pub Date : 2020-01-25
    Shervin Shokuhi; Mahmoud Reza Sohrabi; Shirin Mofavvaz

    In this study, the spectrophotometric method and intelligent chemometrics approaches, including artificial neural network (ANN) and least squares support vector machine (LS-SVM) were developed to determine metformin (MET) and sitagliptin (STG) in the pharmaceutical dosage form. Feed-forward backpropagation neural network (FFBP-NN) with Levenberg Marquart (LM) and conjugate gradient (SCG) algorithms was used. The results of ANN indicated that the LM algorithm with 3 layers and 6 neurons, as well as 5 layers and 8 neurons, had better performance with mean square error (MSE) of 9.12 × 10-29 and 3.56 × 10-29 for MET and STG, respectively. Also, layers 2 and 5 with the 8 neurons showed the least error for MET and STG in the scaled conjugate gradient (SCG) algorithm, respectively. Next, the least support vector machine method was used to estimate the mentioned components simultaneously. The regularization (γ) and width (σ) parameters of the LS-SVM method were optimized based on the leave-one-out (LOO) cross-validation method and the root mean square error (RMSE) of MET and STG were 0.4884 and 0.9336, respectively. Real pharmaceutical sample analysis was performed using the proposed methods and high-performance liquid chromatography (HPLC). One-way analysis of variance (ANOVA) test with a 95% confidence level was applied to the results. Obtained statistical data from the comparison of the proposed methods with the reference technique showed no significant differences.

    更新日期:2020-01-26
  • 20Gbit/s-40 GHz OFDM based LEO-GEO Radio over Inter-satellite optical wireless communication (Ro-IsOWC) system using 4-QAM modulation
    Optik (IF 1.914) Pub Date : 2020-01-24
    Amit Grover; Anu Sheetal; Vigneswaran Dhasarathan

    This work discusses the modeling and the numerical investigation of Ro-IsOWC link between a low earth orbit (LEO) and geosynchronous earth orbit (GEO) satellite. 4-level quadrature amplitude modulation (4-QAM) signal with orthogonal frequency division multiplexing (OFDM) technique has been used to transmit high-speed data between two satellites separated at 35000 km link distance in outer space. The proposed link performance has been numerically evaluated under the impact of operating wavelength, transmission distance, input power, pointing errors, additional losses, and receiver aperture diameter. Signal-to-noise ratio (SNR) and received electrical power of the information signal are considered as the performance metrics to evaluate the link performance. Through numerical simulations, we report a successful transportation of 20Gbit/s-40GHz information between two satellites over a transmission distance of 35000 km using the proposed Ro-IsOWC system. Also, an improved link performance has been investigated in this work by using a Square root module (SRm) technique at the receiver terminal for non-linearity compensation.

    更新日期:2020-01-24
  • Improved photocatalytic efficiency of SnO2 nanoparticles through green synthesis
    Optik (IF 1.914) Pub Date : 2020-01-24
    P.A. Luque; O. Nava; C.A. Soto-Robles; M.J. Chinchillas-Chinchillas; H.E. Garrafa-Galvez; Y.A. Baez-Lopez; K.P. Valdez-Núñez; A.R. Vilchis-Nestor; A. Castro-Beltrán

    In this work, tin dioxide (SnO2) nanoparticles (NP's) were synthesized by means of green synthesis, using different concentrations (1, 2 and 4%) of orange peel of extract (Citrus sinensis) as a reducing agent. The NP's obtained were used for photocatalytic degradation of methylene blue (MB). Using infrared spectroscopy (FTIR) it was possible to observe the characteristic molecular vibrations Sn-O at 1632 cm-1 and Sn-O-Sn at 642 cm-1. With the X-ray diffraction technique (DRX), the NP's were observed to have a tetragonal crystalline structure in the rutile phase. Using X-ray photoelectron spectroscopy (XPS), the positions of the specific energies of 486.8 eV of Sn3d3/2 and 495.4 eV of Sn3d5/2 were found, showing the chemical state of Sn4+. Sample M3 NP's presented: via means of Transmission Electron Microscopy (TEM), an average diameter of was of 4.5 nm; modified band gap values of 3.49 eV; a photocatalytic MB degradation of 94.4% at 120 min. Therefore, the synthesis of SnO2 NP's using Citrus sinensis is a great option for its application both in photocatalytic activities and to eliminate dyes in a small amount of time.

    更新日期:2020-01-24
  • Structural and luminescence studies of Sm3+:CaLa4Si3O13 phosphors: An orange-emitting component for WLEDs application
    Optik (IF 1.914) Pub Date : 2020-01-24
    Vijay Singh; G. Lakshminarayana; N. Singh

    With the help of the conventional sol-gel process, six different concentrations of CaLa4-xSi3O13:xSm3+ (0.005 ≤ x ≤ 0.09) phosphors were fabricated. For all samples, by XRD crystal structure and luminescence features have been examined. Based on the diffuse reflectance spectrum, for CaLa3.91Si3O13:0.09Sm3+ phosphor, both direct and indirect optical band gaps have been computed. Following measured PLE and PL spectra, we found that samples can be pumped efficiently by n-UV or blue LED chips for obtaining an intense orange emission at 598 nm (4G5/2→6H7/2) upon 403 nm (6H5/2→4F7/2) excitation. CIE color chromaticity coordinates (x, y) for both CaLa4Si3O13:0.005 and 0.09 Sm3+ phosphors are computed following their corresponding emission spectra. Under 365 nm UV lamp, CaLa4Si3O13:0.09 Sm3+ sample exhibits a bright orange color emission. In this work, it was found that the CaLa4Si3O13:0.09 Sm3+ phosphor possesses potentiality for YAG:Ce3+ phosphor color rendering index (CRI) improvement in WLEDs, excited by the blue LED chips.

    更新日期:2020-01-24
  • Analysis of Daylight Glare and Optimal Lighting Design for Comfortable Office Lighting
    Optik (IF 1.914) Pub Date : 2020-01-24
    Yue Sun; Xin Liu; Wenjie Qu; Guanying Cao; Nianyu Zou

    The comfortable office lighting is one of the important issues for people’s health and working efficiency. In this paper, the current lighting situation of the office was measured and analyzed. We built an office model with the Rhino software to simulate the daylight environment and calculated the glare with the DIVA plug-in. The results show that the daylight glare is more serious in January, February, November, and December. Try to block out part of the sun to avoid glare in these months and use artificial lighting instead. We used DIALux evo to make an office model to simulate light environment. The lighting environment of the office area was optimized by changing the parameters of the light source and the position of the lamp. The optimal light environment is more energy saving and comfortable.

    更新日期:2020-01-24
  • Investigation of different wave structures to the generalized third-order nonlinear scrÖdinger equation
    Optik (IF 1.914) Pub Date : 2020-01-24
    K. Hosseini; M.S. Osman; M. Mirzazadeh; F. Rabiei

    The present paper explores the generalized third-order nonlinear Schrödinger (GTONLS) equation which is used to model ultra-short pulses in optical fibers. The analysis is carried out systematically by adopting a complex transformation for reducing the GTONLS equation to a couple of nonlinear ordinary differential equations (NLODEs) with specific conditions such that the resulting NLODEs can be solved through the use of well-designed techniques such as the expa -function and unified methods. As an outcome, different wave structures including dark and bright solitons as well as Jacobi elliptic solutions to the model are formally constructed.

    更新日期:2020-01-24
  • Optimization of a rear system based on Titanium Nitride for a flexible CuInSe2 solar cell
    Optik (IF 1.914) Pub Date : 2020-01-24
    Bachir Eddine Messaid; Claire Le Paven; Razika Zair Talaighil; Ratiba Benzerga; Laurent Le Gendre; Florent Marlec; Faycal Bensouici

    Flexible thin film solar cells represent the future. This study concentrates on making CuInSe2 based solar cells non rigid by depositing the rear molybdenum contact onto inox 316. In order to overcome the Inox316 disadvantages such as the metallic impurities diffusion and the surface roughness, a bi-layer TiN/Ti have been introduced between the Mo rear contact and Inox 316. Two techniques have been employed: spray pyrolysis for CuInSe2 and by cathodic magnetron sputtering for Mo/TiN/Ti. CuInSe2 layers deposited onto glass substrates present high crystallinity with (112) preferred orientation at 550 °C. However, these properties disappear for CuInSe2 on Inox316 with missing peak (112) and fall in the ratio Se/Cu from 1.9 to 1.1. According to EDS analysis, these results may be due to the Fe and Cu diffusion from Inox316 to CuInSe2 film, this is why the presence of TiN/Ti bi-layer improves the surface condition of Inox 316 and reduces Iron presence from 9.7% to 1.9% and Cr from 3.8% to 0.5%; this confirms its efficiency to improve the solar cell performance using Inox316 substrate.

    更新日期:2020-01-24
  • CMT Penetration Status Prediction Based on Temperature Field Distribution of weld pool
    Optik (IF 1.914) Pub Date : 2020-01-24
    Rongwei Yu; Lianfa Bai

    The penetration status of welding seam is an important index for evaluating the welding forming quality, most of the traditional methods for predicting the penetration status are based on the vision sensing method, by extracting the two-dimensional or three-dimensional geometric features of weld pool, establishing the relationship between geometric features of weld pool and the penetration status. In this paper, a prediction method of Cold Metal Transfer(CMT) penetration status based on the temperature distribution in the local area of weld pool is proposed, this method does not need to obtain the full field visual information of weld pool, and can realize the prediction of CMT penetration status by detecting the temperature distribution in the local area of weld pool. Based on color CCD, the temperature field detection system of weld pool is designed, and the relatively simple temperature measurement equation is fitted through the calibration experiment. Taking the temperature in the local area of weld pool as the input and the penetration status as the output, by using Support Vector Machine(SVM) for classification, establishing the penetration status prediction model, the experimental results show that the model can effectively predict the CMT penetration status.

    更新日期:2020-01-24
  • Radiometric calibration of a field transfer radiometer
    Optik (IF 1.914) Pub Date : 2020-01-24
    Xionghao Huang; Xin Li; Xiaobing Zheng; Wei Wei; Yang Wang

    Surface reflectance is one of the key parameters used in automated vicarious calibration. Two ground-viewing radiometers are used to measure the surface reflectance in Dunhuang; however, the radiometers degrade over time. A transfer radiometer is used to determine the trends on site. Before the transfer radiometer is used to correct the ground-viewing radiometer, one should perform an absolute radiometric calibration. Three methods are used to calibrate the transfer radiometer and utilize an intercomparison. The difference between the three methods is small. The uncertainty of each method is analyzed and found to be less than 6% at two standard deviations. Two ground-viewing radiometers are corrected by the transfer radiometer, and the degradation of most channels is less than 5%. The good performance achieved in the field indicates that the three methods are viable for calibrating a field transfer radiometer.

    更新日期:2020-01-24
  • Observing the Goos-Hänchen Shift in Non-Integer Dimensional Medium
    Optik (IF 1.914) Pub Date : 2020-01-24
    Iqra Zia Ul Haq; Aqeel A. Syed; Qaisar Abbas Naqvi

    Behavior of the Goos-Hänchen shift due to a planar non-integer dimensional (NID) dielectric interface is studied when observation point is also located in NID medium. Both perpendicular and parallel polarized incident electromagnetic waves are considered in this regard. Impact of variation in value of permittivity and NID parameter on Goos-Hänchen shift is noted. A purpose of the discussion is to highlight the differences between two cases: One when observation point is located in NID medium and other when observation point is located in ordinary medium. Behavior of Goos-Hänchen shift for NID-lossy dielectric interface is also treated.

    更新日期:2020-01-24
  • Performance Improvement of TiO2/CuO by Increasing Oxygen Flow Rates and Substrate Temperature Using DC Reactive Magnetron Sputtering Method
    Optik (IF 1.914) Pub Date : 2020-01-24
    Paulina Sawicka-Chudy; Grzegorz Wisz; Maciej Sibiński; Zbigniew Starowicz; Łukasz Głowa; Maciej Szczerba; Marian Cholewa

    In the present study, TiO2/CuO solar cells have been successfully fabricated for the first time using DC reactive magnetron sputtering for application in PV devices. To improve the performance of TiO2 and CuO solar cells, we increased the oxygen flow rates and substrate temperature during the deposition of TiO2 and CuO thin films compared with our previous work. The structural features by X-ray diffraction and energy-dispersive X-ray spectroscopy spectrum(s) with the atomic percent were analyzed. Next, scanning electron microscopy images with cross-sections were compared. Finally, current–voltage characteristics (I-V) capacitance–voltage (C-V) were determined. The PV parameters, open circuit voltage, short circuit current, fill factor, and efficiency, were then analyzed and compared. We observed a maximum efficiency of 0.24% and an open circuit voltage of 0.14 V. To the best of our knowledge, we attained the fourth highest efficiency reported to date. The C-V and I-V characteristics were compared with theoretical calculations obtained with the solar cell capacitance simulator, SCAPS, program.

    更新日期:2020-01-24
  • Maximum Emission Levels of PhotonicallyGenerated Impulse Radio Waveforms Under SpectralConstraints
    Optik (IF 1.914) Pub Date : 2020-01-24
    Mohamed Shehata; Abdelrhman M. Abotaleb; Moaz G. Ali; Mohamed Farhat O. Hameed; Hassan Mostafa; Salah S.A. obayya

    Since it has been first discovered in the analysis of the black-body radiation problem, the emission of spectrally constrained electromagnetic radiation is frequently encountered at different parts of the spectrum, ranging from microwave (MW) frequencies, up to the visible band of the spectrum. These spectral constraints tend to limit the radiated electromagnetic energy, its spectral density and/or the bandwidth occupied by this energy. In this work, analytical closed-form expressions are developed for the maximum emission levels of photonically generated impulse radio-ultrawide band (IR-UWB) waveforms. Both the energy spectral density (ESD) and the bandwidth constraints imposed on these waveforms are considered. The validity of using the derived expressions as upper bounds on the radiation efficiencies of IR-UWB waveforms in practical UWB systems is experimentally demonstrated. Although the conducted analysis is applied to the MW band, it has the advantage of being applicable to other impulse waveforms that occupy other parts of the electromagnetic spectrum, including the milli-meter wave band and the tera-Hertz band, under arbitrarily different ESD and bandwidth constraints.

    更新日期:2020-01-24
  • Rapid and non-invasive screening of high-risk human papillomavirus using Fourier transform infrared spectroscopy and multivariate analysis
    Optik (IF 1.914) Pub Date : 2020-01-24
    Huixia Mo; Liu Yang; Guohua Wu; Xiangxiang Zheng; Jing Wang; Longfei Yin; Xiaoyi Lv

    Persistent high-risk human papillomavirus (HR-HPV) infection is leading cause for the occurrence of cervical cancer, and timely detection and early treatment of HR-HPV infection can effectively reduce incidence of cervical cancer. In this study, a rapid and non-invasive method for detecting HR-HPV was proposed by using Fourier transform infrared (FT-IR) spectra of cervical exfoliated cells combined with multivariate analysis. A total of 100 spectra were recorded from 50 HR-HPV positive patients and 50 normal subjects. The obvious difference in infrared spectrum between the two groups was mainly shown at 1042 cm-1 (mucin), 1246 cm-1 (amide III), 1396 cm-1 (proteins), 1543 cm-1 (amide II), 1651 cm-1 (amide I), 2361 cm-1 (CO2), 2928 cm-1 (lipids), and 3294 cm-1 (amide A). Then, a principal component analysis-linear discriminant analysis (PCA-LDA) diagnostic model was developed and applied on the FT-IR spectra of normal samples as well as HR-HPV positive patients, and satisfactory classification results were obtained. The diagnostic accuracy, specificity, and sensitivity were 98%, 98%, and 98%, respectively. Furthermore, the area under the receiver operating characteristic (ROC) curve (AUC) was 0.997, which could further demonstrate the feasibility of the PCA-LDA model. Therefore, our exploratory work shows that the combination of FT-IR spectroscopy and PCA-LDA model has great potential for HR-HPV screening.

    更新日期:2020-01-24
  • A Novel Path Strategy Design for Precise 2D and 3D Laser Tube Forming Process; Experimental and Numerical Investigation
    Optik (IF 1.914) Pub Date : 2020-01-24
    S. Esmaeil Khandandel; S.M. Hossein Seyedkashi; Mahmoud Moradi

    Laser tube forming is a flexible process in which the heat generated by the laser beam scanning on the tube surface results in bending. Unlike laser sheet forming, few studies have been carried out on laser tube forming. This originates from the complexity of this process compared to the sheet forming, as well as the limited applicability of the forming strategies. In this research, a new idea is proposed based on the circular scanning method, which is presented in the form of two step-by-step and reverse schemes. Using this new strategy, it would be easy to precisely extract the laser scanning path for all 2D and 3D shapes. Since this strategy is programmable, it can be designed and implemented in a variety of forms only by changing the input parameters. In order to form a desired 2D and 3D shapes on a tube based on this idea, the proposed strategy was verified with both finite element and experimental methods. Fiber laser was used to form the AISI 304 L tubes with certain parameters to achieve a specific bend angle. The experimental results are in a very good agreement with the designed path strategy and FE simulations, which confirms the efficiency and effectiveness of the path scanning strategy proposed in this paper.

    更新日期:2020-01-24
  • About electron cyclotron waves in magnetospheric plasma of outer planetshaving perpendicular inhomogeneous DC electric field
    Optik (IF 1.914) Pub Date : 2020-01-24
    Suresh Chandra; Mohit Kumar Sharma

    Study of electron cyclotron waves in magnetospheric plasma of an outer planet has been a subject of great interest. Inspired with a series of papers published in this field, we have recently discussed the cases of homogeneous DC electric field and of AC electric field taken perpendicular to magnetic field, and of AC electric field taken parallel to magnetic in the magnetosphere. Our results have been very different from those published earlier, which have been found erroneous. We have now discussed propagation of electron cyclotron waves when inhomogeneous electric field is perpendicular to magnetic field in the magnetosphere of an outer planet. We have again found that earlier results for inhomogeneous electric field are erroneous. Further, for propagation of waves parallel to magnetic field, present results are found similar to the case of homogeneous DC electric field, discussed earlier, exhibiting that it does not matter if the perpendicular DC electric field is homogeneous or inhomogeneous.

    更新日期:2020-01-24
  • Equivalence theorem of light waves on scattering from anisotropic media
    Optik (IF 1.914) Pub Date : 2020-01-24
    Xiaoning Pan; Ke Cheng; Xiaoling Ji; Tao Wang

    A new equivalence theorem of light waves on scattering from anisotropic medium is discussed. Specifically, the far-zone spectral density of light waves scattered from Gaussian-correlated anisotropic medium is studied, and conditions for different aniostropic medium to produce identical spectral density distribution are presented. It is found that under some special conditions, far-zone scattered field with complete equivalence (i.e. three-dimensional equivalence theorem) or that with partial equivalence (i.e. two-dimensional equivalence theorem) can be realized. This phenomenon may play an important role in the inverse scattering problem.

    更新日期:2020-01-24
  • Effects of Precursor Concentration on the Microstructural, Optical and Photoelectrochemical Properties of Bi2O3 Films Synthesized by Sol-Gel Method
    Optik (IF 1.914) Pub Date : 2020-01-24
    H. Baqiah; Z.A. Talib; J.Y.C. Liew; A.H. Shaari; Z. Zainal; L.M. Fudzi

    β-Bi2O3 films were prepared by sol-gel method process from solutions with different precursor concentration (M = 0.05 – 0.20). The films were characterized by X-rays diffractions (XRD), field emission electron microscopy (FESEM), atomic force microscopy (AFM), UV-vis spectroscopy, photoluminescence spectroscopy (PL), photoelectrochemical (PEC) and electrochemical impedance measurements. The Bi2O3 deposited film had single phase β-Bi2O3 on ITO substrate while it exhibited mixed phases of ε-, δ- and β-Bi2O3 on glass substrate. By increasing M above 0.05, more XRD patterns were observed and lattice parameter c increased. Besides, crystallite size of films increased first from 19.2 to 26.4 nm at M = 0.05 – 0.15 and then decreased to 19.4 nm at M = 0.20. From AFM, the films consisted of polyhedron-like shape islands with height and distribution increased with increment of M. The surface roughness increased from 10.3 to 18.5 nm for film with M = 0.05 and 0.15, respectively, and then decreased to 14.8 nm for film M = 0.20. Optical band gap decreased from 3.24 eV for film M = 0.05 to 2.89 eV for film M = 0.20. From PEC, photocurrent of films increased with increment of M and had maximum value 3.8 × 10-4 A/cm2 for film M = 0.20 at 0 V versus Ag/AgCl. Electrochemical impedance analysis showed a gradual reduction of charge transfer resistance with increasing M. Finally, β-Bi2O3 films with tailored microstructure were prepared which make it attractive for many applications.

    更新日期:2020-01-24
  • A CAD system for diagnosing Alzheimer's disease using 2D slices and an improved AlexNet-SVM method
    Optik (IF 1.914) Pub Date : 2020-01-23
    Ashkan Shakarami; Hadis Tarrah; Ali Mahdavi-Hormat

    Alzheimer’s disease (AD) is one of the most common type of dementia, and there is no treatment to stop or reverse its progression so far. Since AD is one of the most leading cause of death these days and the cost of caring for this disease is expected to raise dramatically, early diagnosis is really crucial. This paper represents a Computer Aided Diagnosis system (CADs) for diagnosing Alzheimer's disease. In this proposed method for decreasing heavy volumetric computations, 2D slices and consequently 2D convolutional neural network (CNN) is used and only half of the slices with higher quality are selected and half of them are removed. Also, for feature extraction and classification an improved AlexNet-SVM method is proposed which decreases computation volume and improve accuracy and efficiency. In this research, because of the considerable ability of PET images in showing body metabolism, these images are taken into account. The experimental results demonstrate the superiority of the offered model compared to existing models by improving performance and accuracy (Up to 96.39%) and decreasing the complex computations.

    更新日期:2020-01-24
  • Thermal characterization of phase difference among the LP modes in Two-mode fibers based on numerical approach
    Optik (IF 1.914) Pub Date : 2020-01-23
    Muhammad Khairol Annuar Zaini; Yen-Sian Lee; Kok-Sing Lim; Nurul Asha Mohd Nazal; Hang-Zhou Yang; Harith Ahmad

    In this work, we present the use of stochastic parallel gradient descent (SPGD) method for determination of thermal characteristic of the phases of LP11o and LP11e modes in relative to LP01 mode in two-mode fibers. Based on the output beam of the fiber, the composition of mode intensity and the respective phase are numerically determined. The findings indicate that modal phases of LP11o and LP11e linearly vary with increasing temperature. Their thermal sensitivities of LP11o and LP11e modes in relative with LP01 mode are determined.

    更新日期:2020-01-23
  • The effect of coherence between two photons on quantum random walk
    Optik (IF 1.914) Pub Date : 2020-01-23
    Zijing Zhang; Jie Song; Yuan Zhao

    Quantum random walk with two controlled coherent photon is discussed. Two polarization entangled photons with completely coherence are generated by spontaneous parametric down-conversion (SPDC), and then a half wave plate (HWP) is used to perform Hadamard operation for controlling coherence between two photons through rotating the linear polarization direction of one photon. Quantum random walk with two photons from coherence to incoherence transition is explored. The effect of coherence between two photons on the quantum random walk is investigated through two photons controlled from coherence to incoherence transition.

    更新日期:2020-01-23
  • Modifications on Lee`s formula to determinate photo and temperatureelectric performance of InSb nanowire arrays and it`s band gap energy
    Optik (IF 1.914) Pub Date : 2020-01-23
    Liu Changshi

    In order to check potential application of InSb nanowire arrays in the infrared detection field, theoretical prediction on photo and temperature-electric performance of InSb nanowire as semiconductor is very important. In this paper, the Lee`s formula, which describes the relationship of photo-electronic current of metal and incident light frequency, is modified, and theoretical results showed the current-voltage of InSb nanowire, in the dark or under front-side illumination, was precisely explained by modifications on Lee`s formula. Thermionic current was accurately obtained due to theoretical current -voltage. Band gap energy of InSb nanowire was figured out through fitting Richardson-Dushman formula on the temperature-depend thermionic current. The results of application of amorphous InSb nanowire arrays before and after radiation by light prove that the method proposed is credible in this paper.

    更新日期:2020-01-23
  • Investigation of UV Irradiation Response of Optical Fiber Sensors for Radiation Dosimetry
    Optik (IF 1.914) Pub Date : 2020-01-23
    Aseel I. Mahmood; Intisar A. Naseef; Nahla A. Hussein; Nadia F. Muhammed; Shehab A. Kadhim; Suaad M. Ali

    In this work, the investigation of radiation response for modified cladding multimode optical fibres exposed to UV radiation (N2 Laser) in terms of Radiation-Induced Attenuation (RIA) had been presented. The optical fibres were tapered to 65 and 60 µm then dipped into (5 wt % of Germanium to modify the cladding region. By exposing these fibres to different energies of UV irradiation, the transmission spectra were online monitored and recorded every ten seconds to analyze the attenuation changes with the increasing of the radiation dose. The experimental results revealed two points: the first point is that the sensor undergoes the RIA effect which is resulted from the interaction between the radiation and the dopant material, and the second point shows that the sensitivity increases as the diameter of the sensor decrease. From these outcomes, we can conclude that such a sensor can be employed in different dosimetry applications.

    更新日期:2020-01-23
  • Luminescence of Li2W1-0.05Mo0.05O4 crystal under X-ray excitation
    Optik (IF 1.914) Pub Date : 2020-01-23
    V.Ya. Degoda; F.A. Danevich; V.D. Grigorieva; G.P. Podust; V.N. Shlegel; O. Stanovyy

    Luminescence of Li2W1-0.05Mo0.05O4 crystal was investigated under X-ray excitation. A broad emission band with a maximum at ∼ 530 nm was measured at temperature 8 K, two phosphorescence exponential components with decay constants 15 s and 380 s were observed after X-ray irradiation at the low temperature. Thermally stimulated luminescence (TSL) was recorded in Li2W1-0.05Mo0.05O4 crystal after X-ray irradiation at 8 K. Seven clear TSL peaks in the temperature region 8 – 150 K were observed. An equidistant character of the TSL peaks can be explained by oscillatory pattern for thermal-delocalization energies from traps. A delocalization energy value for the most intensive TSL peak at 21 K is calculated. It allowed estimation of the main parameters of the traps in the crystal (delocalization energies and frequency factors). The correspondence between the traps energy and the integer value of the crystal-lattice oscillatory-quanta energy indicates the direct tunneling of a charge carrier into an excited state of the recombination center located near the trap.

    更新日期:2020-01-23
  • Design of the Portable Fiber-Optic Current Transformer for Electrolytic Aluminum Industry
    Optik (IF 1.914) Pub Date : 2020-01-23
    Xiaxiao Wang; Fu Ma; Jia Yu; Xu Liu; Yuning Zhang; Ningfang Song

    A portable fiber-optic current transformer (P-FOCT) based on the Faraday effect utilizing the fiber jumper and the flexible sensing coil is proposed to enhance the portability and improve the design for disassembly of FOCT in the electrolytic aluminum industry. To ensure the accuracy of P-FOCT, the polarization crosstalk of fiber jumper and the conductor eccentric error are studied. According to the theoretical analysis and experimental results, the relative error of P-FOCT would decrease as the distance between the current conductor and the non-closed node of the sensing coil increases. A new sensing head is designed and experiments show that the error is 0.31% at variable temperature from 233K to 343K, which meets the requirement for accuracy in the electrolytic aluminum industry.

    更新日期:2020-01-23
  • The application of SJ-MSD Adder to mean value filtering processing
    Optik (IF 1.914) Pub Date : 2020-01-23
    Jiang Jiabao; Shen Yunfu; Ouyang Shan; Peng JunJie; Wang Xianchao

    Based on the transformations of SJ-MSD (modified-signed digit) addition and the principle of SJ-MSD adder, the application of SJ-MSD adder of TOC to mean value filtering (ternary optical computer) is introduced. The realization of mean filtering processing is presented by reconfiguring SJ-MSD adders on TOP (ternary optical processor) in detail. Experiments show that the mean filter processing in TOC can be carried out successfully with a multiple of SJ-MSD parallel adders with large number of data bits. It also shows a great promise and advantages for the application of TOC in digital image processing and other respects.

    更新日期:2020-01-23
  • Improving the performance of dye-sensitized solar cells by incoporating a novel ZnO:Al charge injection layer
    Optik (IF 1.914) Pub Date : 2020-01-22
    Ian Y.Y. Bu

    In this study, the effect of integrating a ZnO:Al (AZO) charge injection layer into dye-sensitized solar cells (DSSCs) is investigated. The AZO charge injection layer was deposited using a low-cost sol-gel deposition method directly onto fluorine-doped tin oxide (FTO) conducting glass just before TiO2 photoanode coating. The structural and optoelectronic properties of AZO charge injection layer are then investigated as a function of the precursor concentration. The integration of AZO charge injection layer leads to the improvement of power conversion efficiency (PCE) by preventing the electrolyte coming in contact with FTO and improving charge injection from the charge AZO layer. It was found that there is an optimum AZO precursor concentration for charge injection layer deposition and DSSCs fabricated using higher concentration resulted in reduced photovoltaic performance due to reduced light transparency, whilst charge injection layer deposited at lower precursor concentration were found to reduce DSSC performance due to issuficient converage.

    更新日期:2020-01-22
  • Investigations of novel polymorphs of ZnO for optoelectronic applications
    Optik (IF 1.914) Pub Date : 2020-01-22
    Saira Shabbir; A. Shaari; Bakhtiar Ul Haq; R. Ahmed; M. Ahmed

    Being a promising candidate in next-generation optoelectronic applications, the study of new polymorphs of zinc oxide (ZnO) is receiving the great attention of researchers. In this article, we explore optoelectronic properties of seven polymorphs of ZnO such as wurtzite type, sphalerite type, germanium phosphide (GeP) type, 5-5 type, nickel arsenide (NiAs) type, β-beryllium oxide (BeO) type and cesium chloride (CsCl) type by using full-potential linearized augmented plane wave plus local orbital (FP-L(APW+lo)) method within Density Functional Theory (DFT). Tran-Blaha modified Becke-Johnson potential (TB-mBJ) along with Generalized Gradient Approximation (GGA) proposed by Perdew-Burke-Ernzerhof (PBE) as exchange-correlation has been used for the calculations of electronic and optical properties of seven polymorphs of ZnO. Our band structure calculations reveal the considered polymorphs of ZnO as wide bandgap semiconductors. The calculated band gap values of wurtzite type, sphalerite type, GeP type, 5-5 type, NiAs type, BeO type and CsCl type polymorphs of ZnO are 2.901 eV, 2.679 eV, 2.648 eV, 3.127 eV, 2.986 eV, 3.040 eV and 1.853 eV respectively. The wurtzite type, sphalerite type, 5-5 type, NiAs type, and BeO type polymorphs of ZnO exhibit direct bandgap while GeP type and CsCl type polymorphs show indirect bandgap. The optical spectra of these polymorphs of ZnO reveal different reflection, plasmon energies, optical absorption, and refractive indices are considerably anisotropic and present different values in the x- and z-direction. The z-component of the reflectivity and absorption spectra was found larger than the x-component in wurtzite type, 5-5 type and NiAs type polymorphs of ZnO, showing that large reflectivity and optical absorption along z-axis than the x-axis in these polymorphs. This study is believed to provide an interesting guideline for the low-cost and non-toxic new polymorphs of ZnO in cutting-edge optoelectronic applications.

    更新日期:2020-01-22
  • Comparative studies of crystal violet dye removal between semiconductor nanoparticles and natural adsorbents
    Optik (IF 1.914) Pub Date : 2020-01-22
    R. Priya; S. Stanly; S.B. Dhanalekshmi; Faruq Mohammad; Hamad A. Al-Lohedan; Won Chun Oh; Suresh Sagadevan

    Nanoparticle-induced photocatalytic degradation of organic pollutant dyes is considered to be a low cost, environmentally friendly, and cost-effective approach. Also, integrating the photocatalytic degradation technique with that of the adsorption process has many more benefits in terms of effective dye removal. So, in that view, the present study deals with the comparative studies of photocatalytic degradation efficiency of semiconductor nanoparticles (like TiO2 and ZnO) with that of the natural adsorbents towards the removal of crystal violet dye. The changes in the dye removal against the applied parameters like adsorbent and catalyst dosage, pH, contact time, etc were studied.

    更新日期:2020-01-22
  • Improvement of dehazing algorithm based on dark channel priori theory
    Optik (IF 1.914) Pub Date : 2020-01-22
    Miao Wu; Chunmin Zhang; Zuzu Jiao; Guoqing Zhang

    The dehazing algorithm based on dark channel priori theory is an effective method for dehazing of single image. However, it still has shortcomings in some of special cases. In this work, a method is proposed to impair these disadvantages. By considering local smoothness of the sky region, pixels in the bright regions (such as light source, white object, etc.) of the haze image are first excluded from being mistaken as reference pixels, so that the estimation of subsequent parameters is more accurate. Meanwhile, the pixels of the most occurrences are selected to replace the ones in the neighborhood centered on the edge pixels, and the operation is carried out pixel by pixel along the edge contour in replace of the minimum filter. This makes the estimation of transmission near the edge in better agreement with the actual situation, and can effectively avoid the “white haze” which is an artifact caused by the minimum filtering in the areas with the depth of field changing dramatically. Compared with the previous methods, the proposed algorithm in this paper can restore images more clearly, with more image edge details retained, and effectively improve visual effect of the scene in haze weather.

    更新日期:2020-01-22
  • The effect of heat treatment on microstructure and properties of laser-deposited TiC reinforced H13 steel matrix composites
    Optik (IF 1.914) Pub Date : 2020-01-22
    Minglang Zhang; Cong Li; Qiong Gao; Jimi Fang; Tong Li Wu; Ke Hong Wang

    With the development of laser technology, laser processing technology has become increasingly popular in the additive manufacturing, remanufacturing and repairing of hot work molds. Due to the special nature of laser processing technology, it is obviously different from the traditional forging or casting methods, resulting in the need for re-exploration and formulation of the heat treatment process. Therefore, this paper hopes to use laser deposition technology to add hard ceramic phase to prepare H13 steel composites, and to explore the effect of tempering treatment on the microstructure and properties of TiC reinforced H13 steel composites, and to provide theoretical support and practical reference for extending the life of H13 steel. The results indicated that the structure after laser deposition is mainly martensite and fine carbides. With the increase of the proportion of TiC, the structure of the sample becomes more fine and uniform. After tempering,the microstructure of the sample is high-temperature tempered martensite and fine carbides,and the distribution of TiC is more uniform.Compared with untempered amples, the hardness and tensile strength of the sample tempered are lower, but the wear resistance is enhanced.

    更新日期:2020-01-22
  • Facile synthesis and enhanced photo-electrocatalytic performance of TiO2 nanotube/g-C3N4 composite catalyst by a novel synthesis approach
    Optik (IF 1.914) Pub Date : 2020-01-22
    Kemal Volkan Özdokur; Burcu Bozkurt Çırak; Çiğdem Eden; Muzaffar Ahmad Boda; Çağrı Çırak

    TiO2 nanotube/graphene-like carbon nitride (g-C3N4) composite structure was fabricated by a novel synthesis approach. Amorphous TiO2 nanotube arrays was synthesized by anodization. Afterward, g-C3N4 structures were decorated on the amorphous TiO2 nanotube arrays by using thermal polymerization process while anatase phase transformation of TiO2 in progress for the first time. The nanocomposite electrodes were further used for photo-electrochemical degradation of Rhodamine B dye. The homogenous surface morphology, higher crystallinity and more efficient photo-electrochemical performance were obtained by TiO2 nanotube/g-C3N4 composite structure due to better electrical contact and electron transportation by described synthesis approach.

    更新日期:2020-01-22
  • An improved merging method for Gaussian mixture probability hypothesis density filter
    Optik (IF 1.914) Pub Date : 2020-01-22
    Huanqing Zhang; Li Gao

    The random finite set (RFS)-based Gaussian mixture probability hypothesis density (GM-PHD) filter is a promising and efficient suboptimal approximation for the multi-target Bayes filter. However, the GM-PHD filter is unable to track nearby targets caused by the improper position distribution of target-originated measurements. Aiming at the problem, a multi-target GM-PHD filter with an improved component merging method is proposed. Based on a proposed adaptive threshold-based component similarity measure scheme, the improved component merging method is able to avoid incorrect fusion of the components of targets in close proximity and optimize the target components within the target posterior intensity. Experimental results illustrate that the proposed algorithm not only can achieve better estimation accuracy in terms of the target states and its number but also has high computation efficiency when compared against the related GM-PHD-based filters.

    更新日期:2020-01-22
  • Structural and optical properties of Fe3+ doped ZnCdO nanostructures for luminescent application
    Optik (IF 1.914) Pub Date : 2020-01-22
    D.V. Satish; R.V.S.S.N. Ravikumar; M.C. Rao

    In this investigation, we report the results of the prepared Fe3+ doped ZnCdO nanopowder by simple solution method. Several experimental techniques have been performed on the prepared samples to find out the structural, morphological and luminescence properties. X-ray diffraction has revealed that the prepared ZnCdO nanopowder possesses the hexagonal ZnO and cubic-period of CdO phase. SEM image has revealed that the tiny agglomeration of irregular particles have appeared in the prepared samples and also found that the crystallite size of the powder sample is 28 nm. FTIR peaks have revealed that the positions of the ZnO and CdO are at 836 and 860 cm-1. EPR and optical retention examination findings have been undertaken to know the site symmetry of Fe3+ ion. Photoluminescence studies have showed that the prepared material radiates yellowish green light with the CIE coordinates, x = 0.3301 and y = 0.4042. These results have revealed that the prepared nanopowder can find positional application in the preparation of optoelectronic and photoluminescence devices.

    更新日期:2020-01-22
  • 更新日期:2020-01-22
  • Estimating Refractive Index Structure Constant and Extinction Coefficient under Misalignment
    Optik (IF 1.914) Pub Date : 2020-01-22
    Dagang Jiang; Ting Lyu; Xin Liu; Yishuai Yuan; Bin Zhu

    This paper presents two methods, named the irradiance fitting method and the irradiance integration method, for the estimation of refractive index structure constant (Cn2) and extinction coefficient under misalignment. Validations of the methods are carried out based on experimentally obtained speckle images. These two methods are feasible and accurate regardless of whether the optical axis misalignment distance is calibrated, which provides an effective and convenient approach for free space optical communication (FSOC) atmospheric channel research.

    更新日期:2020-01-22
  • Luminescence features of green-emitting CaLa4Si3O13:Ho3+ phosphors
    Optik (IF 1.914) Pub Date : 2020-01-22
    Vijay Singh; Lakshminarayana G.; Akshatha Wagh; Neelam Singh

    In this work, the structural and luminescence properties of a series of CaLa4-xSi3O13:xHo3+ (0.01 ≤ x ≤ 0.11) phosphors prepared by conventional sol-gel technique are reported. The hexagonal phase of the samples was analyzed through X-ray diffraction (XRD). The CaLa4-xSi3O13:xHo3+ phosphors exhibited intense absorption in the visible region of the diffuse reflectance and photoluminescence excitation (PLE) spectrum and presented a highest band at 463 nm ascribed to 5G6+5F1 transition from Ho3+ ions. The Kubelka-Munk (K-M) function was utilized to extract Eg (energy band gap) of the sample from the reflectance spectrum of CaLa3.97Si3O13:0.03Ho3+ phosphor. The Eg =3.83 eV and Eg =3.04 eV were evaluated for the direct and indirect band structure of the CaLa3.97Si3O13:0.03Ho3+ sample, respectively. A strong photoluminescence emission (PL) was observed at 546 nm (green color) for 5S2+5F4→5I8 transition. The concentration quenching was observed beyond x =0.03 mol in CaLa4-xSi3O13:xHo3+ phosphors due to non-radiative energy transfer through cross-relaxation. The chromaticity coordinates of the CaLa3.97Si3O13:0.03Ho3+ phosphor (x = 0.33904, y = 0.65575) recommended its suitability in green emission for white light emitting diode applications. 1 Introduction

    更新日期:2020-01-22
  • Metamaterial Based Sucrose Detection Sensor Using Transmission Spectroscopy
    Optik (IF 1.914) Pub Date : 2020-01-22
    Sajal Agarwal; Y.K. Prajapati
    更新日期:2020-01-22
  • Photoluminescence investigation on orange-emitting Sm3+-doped Ca3MgSi2O8 phosphors
    Optik (IF 1.914) Pub Date : 2020-01-21
    Vijay Singh; G. Lakshminarayana; Akshatha Wagh; N. Singh

    The authors report an investigation on the structural and optical properties of a series of Ca3MgSi2O8:xSm3+ (0.01 ≤ x ≤ 0.11) phosphors. The powder samples were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Diffuse Reflection Spectroscopy (DRS), Photoluminescence (PL) (emission and excitation) spectra and 1931 International Commission on Illumination (CIE) chromaticity coordinates. The sample purity and crystallinity were analyzed by XRD and the crystalline grain size and its distribution were examined through SEM. The DRS spectrum of the Ca3MgSi2O8:0.03Sm3+ phosphor was utilized to extract the direct (Eg =5.06 eV) and indirect (Eg =4.42 eV) bandgap using Kubelka-Munk (K-M) function. Under near UV light (403 nm) excitation, the Ca3MgSi2O8:xSm3+ phosphors exhibited intense emission at 601 nm (dark orange light) for 4G5/2 → 6H7/2 transition. The chromaticity coordinates of the Ca3MgSi2O8:0.03Sm3+ phosphor (x = 0.58093, y = 0.41892) recommended its suitability in dark orange colour emitting display devices.

    更新日期:2020-01-22
  • Optical, electrical and photoluminescence studies on Al2O3 doped PVA capped ZnO nanoparticles for optoelectronic device application
    Optik (IF 1.914) Pub Date : 2020-01-21
    Ravindranadh Koutavarapu; R.K.N.R. Manepalli; B.T.P. Madhav; T. Satyanarayana; G. Nagarjuna; Jaesool Shim; M.C. Rao

    ZnO is a significant II-VI n-type direct bandgap semiconductor material which has shown great attention because of its applications in light-transmitting diodes and photograph detectors. In the present investigation, Al2O3 doped ZnO nanoparticles were prepared by co-precipitation technique utilizing PVA as a host polymer. X-ray diffraction studies revealed the cubic structure of nanoparticles. The determined normal crystallite size of Al2O3 doped PVA capped ZnO nanoparticles was around 12 nm. SEM image showed that the nanoparticles were distributed uniformly with small sized grains consisting of nano dots like tips due to the agglomeration of particles. FTIR demonstrated the trademark vibrational modes of constituent components in the host matrix. The optical studies of all samples displayed close band edge retention at 351 nm (3.26 eV). From the DC studies the conductivity was found to be 3.24 × 10-3 S/cm. EPR studies revealed the crystalline structure and coordination/neighbourhood site evenness of Al2O3 doped ZnO in the host lattice. Photoluminescence studies of Al2O3 doped PVA capped ZnO nanoparticles demonstrated two groups at 416 and 619 nm. The main band was seen in violet and other band in blue region. These studies revealed that the Al2O3 doped PVA capped ZnO nanoparticles materials can be used as LEDs, electroluminescence boards and plasma devices.

    更新日期:2020-01-22
  • EFFECT OF PELARGONIDIN ON CARRIER RECOMBINATION LIFETIME OF CTS QUANTUM DOTS
    Optik (IF 1.914) Pub Date : 2020-01-21
    Maya Mathew; Preetha KC

    In the current work, we have prepared stacks of Copper tin sulphide (CTS)/Pelargonidin core/shell quantum dots on soda lime substrates by SILAR technique. Copper tin sulphide quantum dots were of tetragonal phase matching well with JCPDS 089-4714. The absorption coefficient of the core/shell quantum dots increased while the photoluminescence intensity decreased with increasing shell thickness. Decrease of charge carrier confinement energy due to leakage of wavefunction into the shell is the cause of fall in PL intensity. Three transitions were found in all the samples corresponding to 1Se-1Sh, 1Pe-1Ph and 1De-1Dh transitions using the non-interacting particle model. Charge carrier recombination lifetime of P state was found to be in the order of 100 ns, with lifetime increasing with shell thickness, probably due to the P state being the most occupied at room temperature and decrease of surface trap sites with increasing shell thickness. Owing to the high lifetime of CTS/Pelargonidin core/shell quantum dots, these can be used effectively in solar cells where recombination time is a deciding factor for efficiency and also in bioimaging of living cells and tissues.

    更新日期:2020-01-22
  • The charge transport mechanism of a photodiode made of silver sulfide quantum dots decorated graphene for selective detection of blue light
    Optik (IF 1.914) Pub Date : 2020-01-21
    S.A.E. Ablewi; A. Al-Ghamdi; G.W. Beall

    A novel photodiode made of silver sulfide quantum dots decorated graphene was developed for the first time for the selective detection of blue light. The process of the decoration of graphene surface with silver sulfide quantum dots was performed through the synthesis of Ag2S QDs in the presence of graphene solution via polyol technique. The X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and energy dispersive electron diffraction spectroscopy confirmed the successful decoration of graphene surface with Ag2S QDs. The high-resolution transmission electron microscopy revealed that the Ag2S QDs were distributed uniformly on the graphene surface and the average diameter of these QDs was around 8 ± 2 nm. The optical absorption measurements comprises that the decoration of graphene with Ag2S QDs leads to a red shift of the spectrum and an increase of the optical absorption by two times. The luminescence measurements revealed that the decoration of graphene with Ag2S QDs led to a decrease of the luminescence intensity, implying the efficient separations of electrons and holes. The photo-electrical properties indicated that the Ag2S QDs decorated graphene exhibited photodiode like behavior with high response to blue light. The luminescence intensity exhibited a linear regression against the photocurrent up to 5 Lux. Therefore, the developed photodiode showed a promising potential to be employed as efficient selective photodiode for blue light.

    更新日期:2020-01-22
  • Intra-cavity multi-point sensor for C2H2 detection in photoacoustic spectroscopy based on acousto-optic Q-switched fiber laser
    Optik (IF 1.914) Pub Date : 2020-01-21
    Qinduan Zhang; Jun Chang; Zhenhua Cong; Zongliang Wang; Fupeng Wang; Jiachen Sun; Cunguang Zhu

    In this paper, we reported a new multi-point sensor for C2H2 detection based on photoacoustic spectroscopy and acousto-optic Q-switched fiber laser. Three transmission-type PAS cells were placed inside the fiber laser cavity and used for C2H2 detection simultaneously to demonstrate the potential of spatially resolved measurements. A maximum pulse peak power of ∼544 mW was generated by the acousto-optic Q-switched fiber laser. The signal-to-noise ratios (SNR) calculated from the experimental results was 57.7 dB, 45.1 dB and 57.2 dB. This resulted in a minimum detection limit (MDL) for C2H2 of 1.73 ppmv, 7.82 ppmv and 1.93 ppmv for PAS cell 1, PAS cell 2 and PAS cell 3, respectively.

    更新日期:2020-01-22
  • Comparative investigation of two-dimensional materials for the design of non-reciprocal antennas in terahertz band
    Optik (IF 1.914) Pub Date : 2020-01-21
    Aymen Hlali; Zied Houaneb; Hassen Zairi

    Two-dimensional materials have already demonstrated their potentials in the making of non-reciprocal components. In this paper, we compared the performance of terahertz non-reciprocal antennas made up of magnetized graphene, black phosphorus, and hybrid structure in a view to choose a suitable material for effective non-reciprocal THz antennas. A classical patch antenna is used as the reference antenna to effect the comparisons. The performances of these antennas are analyzed and it was found that the proposed strategy of hybridization of graphene and BP shows better electromagnetic performance with their counterparts. The response of the antenna can be controlled conveniently by adjusting the chemical potential of graphene and it is significantly decreased by adjusting the electron doping of black phosphorus.

    更新日期:2020-01-22
  • A flexible 3D point reconstruction with homologous laser point array and monocular vision
    Optik (IF 1.914) Pub Date : 2020-01-21
    Guan Xu; Hui Shen; Xiaotao Li; Rong Chen

    A 3D recovery approach is achieved by the monocular vision sensor and the homologous laser point array with the arbitrary relative pose to the 2D reference. In the modeling process, firstly, the 3D texture board is moved to different positions in the view field of the vision sensor. Therefore, the laser rays intersect with the cubic board and generate laser points on it. Then, the Plücker matrices of the laser rays are determined by the laser points. The algebraic solution of the joint point of laser rays, the optic center of the projector, is contributed by the singular value decomposition. Thirdly, the laser rays are refined by the algebraic solution of the joint point and represented in the 2D-reference coordinate frame. Finally, the reconstruction is achieved by the calibrated laser rays of the projector. The reconstruction method is experimentally conducted to verify the performance and precision in various measurement conditions. The reconstruction error averages are 0.942 mm, 1.055 mm, 1.374 mm, 2.063 mm, under the 700 mm -1000 mm measuring distances between the vision sensor and the optic center. As there is no strict requirement for the relative installation position and orientation between the laser-ray projector and the 2D reference, the approach prompts the flexibility for the on-site active-vision measurement.

    更新日期:2020-01-22
  • Wave diffraction by an impedance wedge
    Optik (IF 1.914) Pub Date : 2020-01-20
    Yusuf Ziya Umul

    A new diffraction field expression is proposed for a wedge with different face impedances. The modified theory of physical optics based diffraction coefficient is taken into account. The reflection coefficients are expressed in terms of the split functions that occur in the double integral solution of the resistive half-plane problem. The effects of wedge’s each faces are represented separately. The uniform field expression is obtained and compared with the literature for a right-angled impedance wedge numerically.

    更新日期:2020-01-21
  • New investigation of electronic properties of BGaAs/GaAs single quantum well for photonic applications
    Optik (IF 1.914) Pub Date : 2020-01-20
    Tarek Hidouri; Samia Nasr; Faouzi Saidi

    Electronic transition in BGaAs/GaAs single quantum well (SQW) have been performed combining the dimensional Schrödinger equation, band anticroissing BAC and 10-band k.p models. The modeling results have been validated experimentally by photoluminescence (PL), high resolution-X-ray diffraction (HRXRD) and photoreflectance (PR). The calculated results appeared to be consistent with experiments. Surface photovoltage SPV spectroscopy gives a new way to study the bandgap of the boron based-SQW for the first time. New e1-lh1 transition appeared which is specific to the SQW. The suggested structure looks to be a promising candidate for solar cells and photonic applications as well as a reference for the growth optimization and understanding of the electronic properties of related B(In)GaAs/GaAs quaternary alloys.

    更新日期:2020-01-21
  • Photoluminescent Properties of Europium Doped Calcium Orthogermanate (Ca2GeO4) as a Candidate for Red Phosphor
    Optik (IF 1.914) Pub Date : 2020-01-20
    I. Koseva; P. Tzvetkov; P. Ivanov; P. Petrova; R. Tomova; V. Nikolov

    Powder samples of Ca2GeO4 doped with 0.5, 1, 2, 3, 4 and 5 at% Eu3+ were prepared by conventional solid state synthesis technique. XRD analyses confirm obtaining of the pure phase at all dopant concentrations. Emission and excitation spectra show the characteristic peaks of Eu3+ ion. The strongest peak in excitation spectra in the range from 300 to 500 nm is located at 393 nm corresponding to the 7F0→5L6 transition. The luminescent spectra consist of the characteristic peaks of Eu3+ ion. The 5D0→7F2, 4 electric dipole transitions are dominant, confirming that the presence of Eu3+ ion in position without inversion symmetry in the host is preferable. The peaks are split, so the dopant is placed in more than one crystallographic position. CIE coordinates of the samples show emission colors in the red region slightly influenced by the active ion concentration. The sample doped by 1 at% Eu3+ show chromaticity coordinates close to the standard red chromaticity coordinates (0.6270, 0.3726). The obtained results confirm that europium doped Ca2GeO4 by could be used as a red phosphor.

    更新日期:2020-01-21
  • UVB-emitting gadolinium-doped Ba2YZrO6 perovskite ceramic phosphor
    Optik (IF 1.914) Pub Date : 2020-01-20
    Vijay Singh; Sumandeep Kaur; A.S. Rao; N. Singh; J.L. Rao; Muhammad Irfan

    We investigated the structural and luminescence characteristics of Ba2YZrO6:xGd (0.01 ≤ x ≤ 0.11) perovskite ceramic phosphors prepared by sol-gel with dominating cubic phase. The Fourier transform infrared (FT-IR) spectrum depicted various shoulders attributed to the functional groups present in the host matrix. The photoluminescence (PL) spectroscopy exhibited the emission at 315 nm under the excitation of 229 nm light, owing to the P67/2→S87/2 transition. We also observed concentration quenching in the prepared phosphor. Further, the electron paramagnetic resonance (EPR) spectra recorded for the samples under room temperature discerning three main resonance signals with effective g-values 6.02, 2.45, and 1.32.

    更新日期:2020-01-21
  • Schrödinger's cat states and their nonlinear solitonic analogues
    Optik (IF 1.914) Pub Date : 2020-01-20
    R. Peña-Moreno; M.A. Agüero; T.L. Belyaeva; L. Morales-Lara; V.N. Serkin

    Nonlinear solitonic analogues of Schrödinger's cat states arise in the framework of the nonlinear Schrödinger equation (NLSE) model with confining harmonic oscillator potential. In-phase or out-of-phase displaced canonical (linear) Schrödinger's coherent states (well known as the ”male” or ”female” Schrödinger's cats) periodically oscillate and interfere in the crossing central point of confining harmonic oscillator potential. They are self-localized and robust linear solitary waves that do not disperse and preserve their identity after repeated collisions, and, in this sense, they are analogous to the well-known nonlinear bound states of the NLSE solitons. We discuss the main parallels and distinctions between canonical Schrödinger's cat states and their nonlinear solitonic analogues. Our primary aim is to reveal the main features of nonlinear solitonic analogues of Schrödinger's cat states restricted by the quantum-mechanical normalization condition and interpretation. The fulfillment of this condition means that, in general terms, the hypothesis of the possibility to develop nonlinear quantum mechanics can be tested directly by computational experiments with generalized NLSE models. We clarify how the strong short-range nonlinear forces lead to considerable decreasing (or increasing) of the oscillation periods between even and odd soliton-like Schrödinger's coherent states, when they closely approach each other. We demonstrate the possibility to realize the coherent superposition of practically noninteracting displaced solitonic Schrödinger's coherent states with opposite phases. Our analytical results do give a quite good qualitative and quantitative check of the numerical results known so far.

    更新日期:2020-01-21
  • Physical investigations on mixed quaternary oxide Co0.7Fe0.3(MoO4) thin film
    Optik (IF 1.914) Pub Date : 2020-01-20
    A. Arfaoui; A. Mhamdi; M. Amlouk

    This work deals with the synthesis of cobalt iron molybdenum oxide thin films deposited on the glass substrates by the spray pyrolysis technique at 460 ᵒC. First, the structural properties of the prepared samples were analyzed by X-ray diffraction (XRD) and Rietveld refinement techniques showed a monoclinic structure of Co0.7Fe0.3(MoO4). The surface topography performed by the scanning electron microscopy (SEM) shows spherical grains disturbed randomly with sizes varying from 2 to 5 μm. Second, the optical parameters, such as absorption, band gap and refractive index were studied using both the spectrophotometer UV-VIS-NIR and the ellipsometry spectroscopic. In the same line, it is noted that the optical study shows a direct transition with a band gap equal to 1.77 eV and a normal dispersion of refractive index determined by Cauchy formalism. In addition, the photoluminescence (PL) measurements exhibit emission in the visible region with a weak band located around 420 nm and a strong one assigned at 486 nm. Finally, AC conductivity is well described by Jonscher’s law and it is verified that the frequency exponent s has values ≤ 1 and the value of s decrease with increasing temperature, suggesting hopping conduction mechanism. The activation energy Ea equal to 1.13 eV.

    更新日期:2020-01-21
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