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  • Influence of CaO/MgO ratio on Cr3+ to Cr4+conversion efficiency in YAG:Cr4+ ceramic saturable absorbers
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-24
    V.V. Bezotosnyi; A. Yu Kanaev; Yu.L. Kopylov; A.L. Koromyslov; K.V. Lopukhin; I.M. Tupitsyn; E.A. Cheshev

    Transparent Cr4+:YAG ceramics with high optical quality was fabricated using solid state reactive sintering. The effect of CaO/MgO ratio on Cr3+ →Cr4+ conversion efficiency was studied. In samples with fixed total amount of divalent ions, Cr4+ conversion efficiency is growing with increasing of Ca2+/Mg2+ ratio. Samples were fully transparent after sintering at 1840 °C for 8 h and annealing in air at 1400 °C for 10 h. Some rather specific defects were observed, their nature investigated and model of forming proposed. Most probable nature of these defects is tungsten inclusions in ceramics sourced by tungsten vapors inside the vacuum furnace. This is far more pronounced with high calcium oxide presence in ceramic samples. The main saturable absorber characteristics were systematically measured.

    更新日期:2020-01-24
  • High-performance hybrid white organic light-emitting diodes with bipolar host material and thermally activated delayed fluorescent emitter
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-24
    Jinjiang Wang; You Li; Liezun Chen; Yanhong Deng; Yuqi Peng; Feiping Lu; Weihua Zhu
    更新日期:2020-01-24
  • Terbium concentration effect on magneto-optical properties of ternary phosphate glass
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-24
    Anastasiia Babkina; Ekaterina Kulpina; Yevgeniy Sgibnev; Yuriy Fedorov; Aleksey Starobor; Oleg Palashov; Nikolay Nikonorov; Alexander Ignatiev; Ksenia Zyryanova; Kseniya Oreshkina; Evgeny Zhizhin; Dmitrii Pudikov

    Ternary phosphate glass doped with different terbium concentration (up to 35 wt.%) is synthesized via standard melt-quenching technique. The effect of terbium content on physical, optical, and magneto-optical properties is investigated. Two glass transition regions on DSC curve at 35 wt.% Tb2O3 demonstrate phase-separation process. Transmittance spectra demonstrate maximum 0.2 cm−1 level in optical transmittance window of 400–1600 nm limited by standard absorption bands for terbium-containing materials. Metaphosphate groups in as-synthesized glass structure are predominant over polyphosphate complexes with no ultraphosphate units regardless to composition changes. After the additional heat treatment the partial depolymerization of glass structure occurs resulting in formation of big amount of Q0 and Q1 units. Glass refractive index varies from 1.5872 to 1.5814 with terbium content increase. The concentration dependence of Verdet constant is non-linear due to the presence of Tb4+ ions, which was confirmed by the XPS analysis results. The value of 15 rad/T/m at 1064 nm is reached for 35 wt.% Tb2O3-doped glass. The results indicate the viability of the considered glass series with high terbium oxide concentration to be attractive media for magnetooptical devices working in VIS and near IR ranges.

    更新日期:2020-01-24
  • Intensity dependent nonlinear absorption switching behavior of electrospun meta-nitroaniline nanofiber
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-24
    C. Yogeswari; K.M. Hijas; T.C. Sabari Girisun; R. Nagalakshmi

    The present work reports the study on nonlinear absorbing behavior of optically nonlinear m-nitroaniline (mNA) organic molecules properly oriented in the core of a polymeric fiber such as Poly (methyl methacrylate) (PMMA) and Poly (ethylene Oxide) (PEO) free standing films synthesized by electrospinning technique for the first time. The nonlinear absorption nature of the nanofibers is investigated by intensity dependent Z scan technique (532 nm, 10 Hz, 5ns). We observed an unusual nonlinear switching behavior in mNA- PMMA nanofiber from reverse saturable absorption (RSA) to saturable absorption (SA) through a peculiar W-pattern for an increase in pulse energy, whereas intensity dependent SA behavior is seen clearly in mNA–PEO polymer matrix. The identified nonlinear absorption of mNA –PMMA and mNA -PEO fibers can be of interest for various optical applications such as switching, optical sensors, etc. The normalized transmittance versus input fluence graph confirms the potential possibility of using the prepared fibers as optical switches at higher intensity. And mNA – PMMA fiber matrix at low intensities exhibits an optical limiting behavior, implying that the material to be a potential candidate for laser safety devices. Demonstrated fiber matrix free standing films are of potential use as it finds direct application in laser photonic devices.

    更新日期:2020-01-24
  • Enhancement of luminescence in Er3+ doped Ge20Ga10S70 glass-ceramics
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-24
    Zhen Yang; Rongping Wang; Yimin Chen; Qiuli Li; Xiang Shen; Tiefeng Xu

    We have fabricated Ge20Ga10S70 glasses doped with 1.0 at% Er and annealed them to create chalcogenide glass-ceramics. We further characterized their optical transmission, luminescence, and microstructure for investigating the mechanism of the fluorescence enhancement. The results showed that, Ga2S3 and GeS2 crystals are precipitated successively, the transmittance of the glass-ceramics decreases, and the transmission edge shifts towards longer wavelengths with prolonged annealing time. Photoluminescence (PL) intensity at 1.54 μm in glass-ceramics with 20 h annealing time is twice than that in the base glass. From the similar evolution of PL and XRD intensity, we concluded that the luminescence enhancement is related to the Ga2S3 crystals in glass-ceramics. The Er ions are registered near tht Ga2S3 crystalline grains with a size of 50 nm as evident by elemental mapping. The results are helpful to optimize the chalcogenide glass components doped with REI and improve the solubility of REI.

    更新日期:2020-01-24
  • The synthesis of Ba1-x(Ca/Sr)xGdF5: Er3+, Yb3+ and its upconversion properties
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-24
    Xu Wang; Chongji Zhang; Qun Jiang; Meitang Liu; Mansen Wang; Hongwen Ma; Yuqing Kuai

    In present work, we succeeded in synthesizing new series of upconversion materials as Ba1-x (Ca/Sr)x GdF5: Er3+, Yb3+ by hydrothermal method. Surprisingly, we found that the doping of both ions can apparently affect the optical performance of these materials. The Ca2+ doping increases the proportion of green light while the Sr2+ doping increases the proportion of red light, which could be used in emission color tuning. Meanwhile, when the ion doping amount reaches 15%, the luminescence intensity of the two materials is 5–6 times higher than that of undoped materials respectively, which reveals that the luminescence efficiencies are great improved. This study testifies that this new series of Ba1-x(Ca/Sr)xGdF5: Er3+, Yb3+ exhibit great potential in the application of new developed upconversion materials.

    更新日期:2020-01-24
  • Enhanced photocatalytic activity of ZnO sensitized by carbon quantum dots and application in phenol wastewater
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-24
    Huiqin Liang; Xiumei Tai; Zhiping Du; Yanji Yin

    This work reports on preparation of ZnO composites sensitized by carbon quantum dots (CQDs) and its photocatalytic degradation on phenol under visible-light illumination. With the help of tools such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS), UV–vis diffusive reflectance spectra (UV–Vis DRS) and gas chromatograph-mass spectrometer (GC-MS), successful synthesis of ZnO composites sensitized by CQDs has been confirmed, which extend the spectral response range of the procatalyst to the visible region enhancing the utilization of sunlight. Meanwhile, transient photocurrent response and Nyquist plot analysis were further proved the increase in carrier separation efficiency of the procatalyst. The photocatalytic ability of the composites was measured by XPA-7 photocatalytic instrument with using phenol as simulate pollutants. And the photocatalytic reaction mechanism was also revealed by the Mott-Schottky plot, band structure and trapping experiments of active species. The results exhibit that the photocatalytic performance of ZnO composites sensitized by CQDs is 60% higher than that of pure ZnO with good stability and reusability, whose utilization has almost no significant change after 10 cycles.

    更新日期:2020-01-24
  • Comprehensive study of photoluminescence and cathodoluminescence of Eu and Tb doped Mg2SiO4 prepared via a solid-state reaction technique
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-24
    Z.G. Portakal Ucar; S. Akca; T. Dogan; Y.Z. Halefoglu; U.H. Kaynar; M. Ayvacikli; J. Garcia Guinea; M. Topaksu; N. Can
    更新日期:2020-01-24
  • Facile spray pyrolysis fabrication of Al:CdS thin films and their key linear and third order nonlinear optical analysis for optoelectronic applications
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-24
    M. Aslam Manthrammel; Mohd. Shkir; Mohd Anis; S.S. Shaikh; H. Elhosiny Ali; S. AlFaify

    Different quantity of aluminium (Al) doped CdS thin films are fabricated through a facile and cost-effective spray pyrolysis route. Elemental composition and mapping studies approved the presence of Al and its homogeneous distribution throughout the films. The surface morphology of films is found to be modified by Al doping content. X-ray diffraction studies show that the grown films are of hexagonal crystal system. The crystallite size was estimated in range from 16 to 22 nm. Lattice parameters were determined using POWDERX software and confirm single phase of CdS. Vibrational study possesses fundamental phonon modes in all fabricated films related to single hexagonal phase of CdS. Optical study confirms that the films are low absorbing and high transparency. The estimated values of refractive indices are noticed in the range of 1–2.8. Real and imaginary parts of permittivity and loss tangent values were calculated. Furthermore, the linear susceptibility, nonlinear cubic susceptibility, and refractive index were obtained using z-scan technique and observed to be enhanced from 1.17 × 10−6 to 4.66 × 10−6 cmW−1, 3.68 × 10−5 to 6.93 × 10−5 esu. and 2.89 × 10−8 to 5.11 × 10−8 cm2W−1, respectively.

    更新日期:2020-01-24
  • Study of structural and optical properties of MBE grown nonpolar (10-10) ZnO/ZnMgO photonic structures
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-24
    M. Stachowicz; J.M. Sajkowski; S. Kryvyi; A. Pieniazek; A. Reszka; A. Wierzbicka; M.A. Pietrzyk; E. Przezdziecka; D. Jarosz; K. Gwóźdź; E. Placzek-Popko; E. Alves; S. Magalhães; A. Kozanecki

    Two types of simple monolithic photonic ZnO/ZnMgO structures, differing by a factor of two in thicknesses of individual components and grown on m-ZnO substrates, are tested to determine limitations in obtaining their good quality at Mg concentrations close to the limit for phase segregation (~40–45%). The studied structures were composed of 5.5 pairs of ZnO/ZnMgO bilayers (20/22 and 40/45 nm), the central ZnO microcavity (70 and 140 nm) and 5 bilayers on top. Actual layer thicknesses were verified using Scanning Electron Microscopy. Rutherford Backscattering Spectrometry was used to determine the Mg content. The X-ray rocking curves revealed high periodicity and proved that the wurtzite structure was retained without precipitates of foreign phases. Reciprocal space maps and the calculated lattice constants indicated that the layers were strained. Excitonic lines in cross-sectional cathodoluminescence (CL) spectra from individual ZnO layers are blue-shifted compared to emissions from ZnO substrates, thus confirming the presence of strain. The CL intensity of the first ZnMgO layers deposited on ZnO substrates and on both interfaces of the central microcavities was low thus suggesting an effective generation of misfit defects, especially in thicker structures. Reflectivity measurements confirmed the existence of cavity resonance at 385 nm and stop band at 370–400 nm in the photonic structure with a 140 nm microcavity. The results show that defect engineering at the initial stages of deposition of ZnMgO layers with high Mg is critical for the optimization of all-ZnO photonic structures.

    更新日期:2020-01-24
  • Design and measurement of a narrow band metamaterial absorber in terahertz range
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-24
    Min Zhong

    In this paper, we proposed and measured a metamaterial absorber with cross metal array in 12–28 THz range. A narrow absorption band (the absorption amplitude is 96%) is obtained at resonance frequency 19.24 THz, which is excited by the bright-bright modes coupling effect. Impedance matching is achieved at this resonance frequency between samples and free space. This absorption peak is enhanced and its resonance frequency is shifted with lattice constant reducing or structural parameter w1 increasing. The absorption peak is highly sensitive to the variation of structural parameters due to the bright-bright modes coupling effect on the cross strips. An equivalent LC circuit mode is proposed to understand the physical mechanism of the resonance frequency shifting. The effect of three gases on this absorption peak is measured. Moreover, high absorption performance is revealed when the incident angle reaches 480.

    更新日期:2020-01-24
  • Amplified spontaneous emission and optical gain characteristics of sexithiophene single crystals
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-23
    Muhammad Tahir; Muhammad Hassan Sayyad; Suhana Mohd Said; Mohd Faizul Mohd Sabri; Mahidur R. Sarker

    This paper reports optical properties of a single crystal thiophene/phenylene co-polymer 5,5ʺʺ'-diphenyl-2,2′:5′,2ʺ:5ʺ,2ʺ′:5ʺ′,2ʺʺ:5ʺʺ, 2ʺʺ'-sexithiophene (P6T). The P6T crystals demonstrate high charge carriers’ mobility and large photoluminescence quantum efficiency (PLQE). Herein, the stimulated emission of P6T is studied within wide range of pump energies –refers to energy per pulse – (from 19 ± 0.5 μJ/cm2 to 64.2 ± 0.5 μJ/cm2) through amplified spontaneous emission (ASE) measurements by using Nd-YAG femtoseconds tunable pulsed laser at 445 nm excitation wavelength (λexc). ASE measurements exhibit lower threshold energy density (Eth) i.e., ~26 ± 0.5 μJ/cm2 which confirms optical amplification in P6T at 632 nm emission wavelength. The ASE characteristics of P6T are also studied as a function of different λexc ranging from 425 to 475 nm to find the wavelength for optimum amplification. It is observed that the maximum optical amplification for P6T occurs at a λexc of 445 nm. These crystals exhibit large optical gains which are measured to be 69 cm−1, 53 cm−1 and 29 cm−1 at excitation energies of 91 ± 0.5 μJ/cm2, 66 ± 0.5 μJ/cm2 and 43 ± 0.5 μJ/cm2, respectively. PL measurements of P6T crystals demonstrate large value of the PLQE ~57.36%. This study suggests the potential of P6T single crystal as one of the good candidates among high optical gain materials of its kind for its possible applications in solid-state lasers, photodetectors and optical amplifiers.

    更新日期:2020-01-23
  • The optical properties of GeSe2 nano-films prepared by CVD
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-22
    Can Wang; Yu-hua Wang; Zu-zhao Xiong; Pei-ling Li; Luo-he Zhou; Hong-zhe chen; Yu Lu; Chen-rui Zhao; Yan-qing Chen; Xiang-Xiang Yu

    GeSe2 Nano-Films (GeSe2NFMs) were prepared by chemical vapor deposition (CVD). The nanostructures of the GeSe2NFMs were revealed by X-ray diffraction and Raman spectroscopy, respectively. The linear optical properties of the samples have been studied by absorption spectroscopy. The nonlinear optical properties of the GeSe2NFMs have been studied by Z-scan technique with femtosecond pulses at the wavelength of 1030 nm. The measured band gap of GeSe2NFMs is 2.33eV, and the nonlinear absorption coefficient βeff is about 1.344*10−7 cm/W, which is a saturated absorption. In addition, in the fluorescence emission spectrum of GeSe2NFM, we found emission peaks in the red and infrared light regions with a wavelength of 760 nm. We found that GeSe2NFMs prepared by CVD has a larger band gap and a larger nonlinear absorption coefficient than the doped GeSe2. These studies indicate the application of GeSe2NFMs in laser emitters and nonlinear optical devices, and also provide a reference for subsequent research on nonlinear optical characteristics.

    更新日期:2020-01-23
  • A new far-red emission from Zn2SnO4 powder synthesized by modified solid state reaction method
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-21
    L.T.T. Vien; Nguyen Tu; Manh Trung Tran; Nguyen Van Du; D.H. Nguyen; D.X. Viet; N.V. Quang; D.Q. Trung; P.T. Huy
    更新日期:2020-01-22
  • Spectroscopic and thermal nonlinearity study of a Schiff base compound
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-22
    Faeza Abdulkareem Almashal; Mohammed Qasim Mohammed; Qusay M. Ali Hassan; C.A. Emshary; H.A. Sultan; Adil Muala Dhumad

    Schiff base compound 2, 4 hydroxy-4- carboxy benzylidene aniline (C14H11NO4) was successfully synthesized by condensation reaction of 4-amino benzoic acid and 2, 4-hydroxy benzaldeyhyde. The functional groups have been confirmed via Fourier-transform infrared spectroscopy (FTIR) analysis. The Nuclear magnetic resonance (NMR) spectroscopy was used to identify the placement of protons in the obtained compound. UV–visible absorption spectrum was obtained at room temperature for the compound. Diffraction ring patterns were observed when the Schiff base compound was irradiated with a continuous wave laser beam of wavelength 473 nm. The type of the obtained patterns depends on the type of the laser beam wave front. Based on the number of rings the total change in the compound refractive index and the nonlinear refractive index were obtained. The experimental diffraction ring patterns were successfully simulated using the Fresnel-Kirchhoff diffraction theory with good qualitative and reasonable quantitative agreements between experimental and theoretical findings. Both the open and closed aperture Z-scans were performed to measure the nonlinear absorption coefficient and nonlinear refractive index of the Schiff base compound, respectively. The optical limiting behavior of the Schiff base compound was tested too.

    更新日期:2020-01-22
  • Bridgman growth and magneto-optical properties of CeF3 crystal as Faraday Rotator
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-20
    Huifang Li; Jingya Wang; Junfeng Chen; Yun Dai; Liangbi Su; Xiang Li; A.M. Kalashnikova; Anhua Wu

    In this work, CeF3 crystal with maximum diameter of 35 mm was successfully grown with the Bridgman-Stockbarger (BS) method. The crystal diffraction peaks match well with the standard pattern of CeF3 (PDF#01-089-0967), which proofs that obtained samples are of high purity. The transmittance of CeF3 crystal is relatively high in the UV-NIR region and reach 92% in comparison with TGG crystal. The UV cut-off absorption edge of CeF3 crystal is located at 270 nm contrary to 400 nm for TGG. The Verdet constant of CeF3 crystal is largest at 450 nm wavelength and reach 247 rad/T m. The results show that CeF3 possess better optical and magneto-optical properties than TGG. CeF3 can be a potential candidate for Faraday Rotators used in the field of high-power lasers.

    更新日期:2020-01-21
  • 更新日期:2020-01-21
  • Effect of Sn content on some optical properties of Se90Pb10-x thin films
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-20
    Ebraheem O. Hawarat; Mousa M.A. Imran; Omar A. Lafi; Hassan K. Juwhari; Bashar I. Lahlouh; N. Chandel; N. Mehta

    Se90Pb10 and Se90Pb8Sn2 thin films of thickness 400 nm were evaporated on glass substrates. The glassy nature of the prepared films was ascertained by differential scanning calorimeter thermograms and X-ray diffraction patterns. Spectra of reflection and transmission of the prepared films were recorded using FilmTek3000 in the wavelength range of 300–900 nm. The absorption coefficient was calculated and used to evaluate the optical band gap energy which comes out to be 2.1 and 2.2 eV for SePb and SePbSn thin films, respectively. The extinction coefficient (k), refractive index (n), real (ε′) and imaginary (ε") dielectric constants were also obtained. Results indicate that the addition of Sn content reduces the value of (n), (ε′) and (ε"), while that of k increases. The observed changes in the studied optical parameters were interpreted depending on the chemical bond approach of Tichy and Ticha.

    更新日期:2020-01-21
  • Evaluation of the structural and optical characters of PVA/PVP blended films
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-20
    N.M. Deghiedy; S.M. El-Sayed

    The effect of gamma irradiation on the optical and structural properties of poly(vinylalcohol) (PVA)/poly (vinylpyrrolidone) (PVP) blends was investigated in this study. The PVA/PVP films were formulated by mixing and casting method with increasing PVA ratios. The dried films were irradiated at 30 kGy and the impact of gamma irradiation on the characteristics of these films was inspected using FTIR, XRD, SEM and UV–vis techniques in the wavelength range (200–1200) nm. Swanepole method was used to compute the optical constants, optical band gap and complex dielectric constant whereas Wemple-DiDmenico model was applied to develop the optical dispersion parameters Eo and Ed. Additionally, the high frequency dielectric constant (ε∞) for all films was recorded. A slight shift in the FT-IR spectra and increase in the transmittance for all films post-irradiation were detected and the XRD analysis depicted the crystalline nature of the PVA/PVP films which was further confirmed by the surface morphology images obtained by the SEM. In conclusion, gamma irradiation and increasing the PVA to PVP ratio improved the optical properties of the films.

    更新日期:2020-01-21
  • Dual-emitting Eu2+/Eu3+ co-doped Ca9Zn1.5(PO4)7 phosphor for self-calibrated optical thermometry
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-20
    Hua Yu; Fengping Ruan; Leifeng Chen; Degang Deng

    Ca9Zn1.5(PO4)7: Eu2+/Eu3+ phosphors had been synthesized via conventional high temperature solid-state reaction. Based on the different thermal quenching characteristics between 4f-5d transition of Eu2+ ions and 4f-4f transition of Eu3+ ions, the fluorescence intensity ratio (FIR) of Eu3+ to Eu2+ exhibits temperature dependence at the temperature from 293 to 473 K. The maximum absolute and relative temperature sensitivity of Ca9Zn1.5(PO4)7: Eu phosphor can reach up to 0.0034 K−1 and 1.4% K−1 at 453 K, respectively, when used as thermometric material. These results indicated that our study opens up an effective approach for developing other high-performance self-calibrated optical thermometers.

    更新日期:2020-01-21
  • Q-switched mode-locked Nd:GGG waveguide laser with tin disulfide as saturable absorber
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-20
    Xuejian Dong; Ziqi Li; Chi Pang; Ningning Dong; Hailing Jiang; Jun Wang; Feng Chen

    We demonstrate a Q-switched mode-locked waveguide laser operation with high fundamental repetition rate based on the few-layer tin disulfide (SnS2) as a saturable absorber. The excellent nonlinear optical property of SnS2 enables efficient pulsed laser generation. By using Nd:GGG ridge waveguide, the fundamental repetition rate up to 17.9 GHz has been achieved for the mode-locked pulses with duration as short as 30 ps. In addition, this Nd:GGG-based waveguide laser exhibits excellent lasing properties (maximum output power of 115 mW at 1064 nm) by modulation of SnS2, suggesting promising application as miniature ultrafast light sources.

    更新日期:2020-01-21
  • Enhanced self-powered photoresponse in perovskite films with in situ induced p–n homojunction by Ar+ bombardment
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-20
    Lixia Ren; Min Wang; Ming Li; Sheng Wang; Shuanhu Wang; Yang Zhao; Muhammad Asad Iqbal; Kexin Jin

    In the past ten years, hybrid perovskite materials have attracted extensive research attention due to their outstanding physical properties. Further improvement in the photoresponsive performance is limited by the recombination of charge carriers in the perovskite films. Here, by controlling the stoichiometry of precursors, p-type perovskite films are obtained. The transformation of p-type to n-type in the surface layer of CH3NH3PbI3 film is dramatically achieved by Ar+ bombardment. An n/p-type perovskite homojunction is successfully in situ induced, whose built-in electric field could promote the oriented transport of photo-induced carriers. This perovskite homojunction exhibits an increased Ilight/Idark ratio by almost one order of magnitude at room temperature under 532 nm light irradiation. The Ar+ bombardment method has generic appeal, and its key attributes-in situ induction of p–n homojunction-improve the unicity of preparation for growing perovskite homojunction and make this method potentially suitable for future multifunctional perovskite-based photoelectric devices.

    更新日期:2020-01-21
  • A spirofluorene-end-capped bis-stilbene derivative with a low amplified spontaneous emission threshold and balanced hole and electron mobilities
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Shi-Bin Ruan; Chin-Yiu Chan; Hao Ye; Ko Inada; Fatima Bencheikh; Atula S.D. Sandanayaka; Toshinori Matsushima; Chihaya Adachi
    更新日期:2020-01-16
  • Highly fluorescent carbon dots from quinoline insoluble residues in coal tar
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Niloy Kundu; Prasenjit Bhunia; Supriya Sarkar; Pinakpani Biswas
    更新日期:2020-01-16
  • 更新日期:2020-01-16
  • Imaging sweat pore structures in latent fingerprints and unclonable anti-counterfeiting patterns by sensitizers blended LaOF:Pr3+ nanophosphors
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    C. Suresh; G.P. Darshan; S.C. Sharma; M. Venkataravanappa; H.B. Premkumar; S. Shanthi; K.N. Venkatachalaiah; H. Nagabhushana
    更新日期:2020-01-16
  • Rapid synthesis of B-N co-doped yellow emissive carbon quantum dots for cellular imaging
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Yingying Wei; Lin Chen; Junli Wang; Xuguang Liu; Yongzhen Yang; Shiping Yu
    更新日期:2020-01-16
  • Structural characterization and optical properties of zeolitic imidazolate frameworks (ZIF-8) for solid-state electronics applications
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    A.M. Aboraia; A.A.A. Darwish; V. Polyakov; E. Erofeeva; V. Butova; H.Y. Zahran; A.F. Abd El-Rehim; H. Algarni; I.S. Yahia; Alexander V. Soldatov

    Zeolitic imidazolate frameworks (ZIF-8) thin films were fabricated via layer by a layer deposition method. The investigation of X-ray diffraction (XRD) of the ZIF-8 powder form was seen to be polycrystalline with a single cubic-phase structure. The lattice parameters and Miller index were calculated using Rietveld refinement by Fullprof software. XRD of ZIF-8 film demonstrates an amorphous structure. The morphology of the ZIF-8 films has therefore been studied with the scanning laser microscope method and found that the homogeneity and surface enhance with increasing the film thickness. On the other hand, it is found that ZIF-8 films have a direct electronic transition with two energy bandgaps (3.62 and 4.58 eV) and their values independent of the thickness of the films. The optical constants were calculated, and the refractive index esteems increment with expanding of the film thickness. This outcome might be credited to the interlude of the film in the preliminary phase of the deposition. The nonlinear optical constants for ZIF-8 film were calculated, and the third-order optical nonlinearity was expanded with expanding the film thickness.

    更新日期:2020-01-16
  • Optical properties of silver nanoparticles deposited onto silicon substrates by different soft-solution processing techniques
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Juan Agustín Badán; Elena Navarrete-Astorga; Rodrigo Henríquez; Francisco Martín; Ricardo E. Marotti; José Ramón Ramos-Barrado; Enrique A. Dalchiele

    Silver nanoparticles have been grown onto crystalline silicon substrates. Three soft-solution one-step processing techniques have been assayed: electroless metal deposition (EMD), electrodeposition (ED) and spray pyrolysis (SP). The shapes exhibited by the silver nanoparticles prepared by EMD and ED are hemispherical, while the shapes of those prepared by SP (for long processing times) are similar to disks of aspect ratio 0.5 approximately. Integrated total reflectance spectra and integrated diffuse reflectance spectra shows distinctive features due to the electronic structure of silicon. Specular reflectance spectra of samples (except those grown by SP with long processing times) show a dip, corresponding to a surface plasmon resonance. Simulations, considering granular composite media were made. The simulated spectra confirm the presence of the spectral dip. Surface plasmon resonance show shifts with the angle of incidence. For samples prepared by ED, the tendency is the same as the one of the model, indicating that there is not much coupling between nanoparticles.

    更新日期:2020-01-16
  • Plasmonic responses of Cu–Ag bimetallic system: Influence of distinctiveness and arrangements
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Mengfan Liang; Qiang Lei; Shuhong Sun; Yan Zhu

    In this article, the effect of the distinctiveness and arrangements on the plasmonic resonance of Cu–Ag system were studied by finite element method, and the effect of morphologies on the plasmonic properties of [email protected] [email protected] NPs and Cu–Ag corn-cob liked NPs was investigated by experiment. For [email protected] core-shell structure, as the fixed thickness of Ag-shell at 10 nm, the dipole plasmon resonance gradually blue-shifts with increasing the radius of Cu core, and as the fixed radius of Cu-core at 50 nm, the feature peak shows a red-shift and broadening with increasing the thickness of Ag shell. For Cu–Ag corn-cob structure, the feature for different Ag coverage are similar to each other and most of the them follow the blue-shifted tendency with the increase the degree of Ag-coverage. Furthermore, as the regular-shaped structure increases (form trigonal to spherical), the plasmon resonance gradually blue shifts, and finally, we use two parameters to describe the different idealized Cu–Ag structure: separation, exterior contact, intersection and [email protected] The combined information from our simulation and experiment will give guidelines for choosing adequate particles when aiming at certain plasmonic properties.

    更新日期:2020-01-16
  • Optically-stimulated luminescence properties of Eu-doped Cs(Cl, Br) translucent ceramics
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Hiromi Kimura; Takumi Kato; Daisuke Nakauchi; Noriaki Kawaguchi; Takayuki Yanagida

    We have developed Eu-doped Cs(Clx, Br1-x) (x = 0, 0.25, 0.5, 0.75, 1) translucent ceramics by the spark plasma sintering technique and evaluated their optical and optically-stimulated luminescence (OSL) properties. As the optical properties, the transmittances of all the samples were 20–60% in the visible range, and the absorption bands around 260 and 350 nm due to 4f-5d transitions of Eu2+ were confirmed. After X-ray irradiation, all the samples showed the new absorption band around 600–700 nm. When increasing x, the generated absorption peak position shifted to shorter wavelength. Regarding the OSL properties, all the samples showed a broad OSL emission peak around 440 nm, and the origin was 5d-4f transitions of Eu2+. The peak positions of the OSL stimulation spectra shifted to shorter wavelength with increasing x. The dose sensitivities using OSL were confirmed to be as low as 0.01 mGy in all the samples.

    更新日期:2020-01-16
  • High performance CsPbBr3 perovskite nanocrystal vertical phototransistor with graphene electrode
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Yongli Che; Xiaolong Cao; Yating Zhang; Jianquan Yao

    All-inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, and I) nanocrystals (NCs) have been extensively studied as optically active materials in photodetectors, light-emitting diodes, solar cells and lasers, in view of their combination of the outstanding characteristics of perovskites and NCs such as low cost, solution processability, bandgap tunability, and large absorption coefficient. Here we report the fabrication of graphene electrode based CsPbBr3 NCs vertical field-effect phototransistor (VFEPT), exhibiting high photoelectrical performances benifiting from the ultrashort channel, the high ultraviolet–visible absorption of CsPbBr3 NCs, and the adjustable Fermi level of graphene. The VFEPT exhibited high drain current density of 0.25 A/cm2 for p-type and 0.2 A/cm2 for n-type transports in dark condition. The responsivity, effective quantum efficiency and detectivity reached as high as 2.2 × 103 A/W, 6.7 × 105%, 1.1 × 109 Jones at an irradiance power of 342 mW/cm2 under 405 nm illumination. Additionally, the device showed excellent stable and reproducible dynamic response to cyclical optical signal, with the rise and decay time as fast as 20 ms/36 ms. The device described here has great potential applications in high-sensitivity, high-speed, and low-power nanometer-scale photodetectors.

    更新日期:2020-01-16
  • Dodecanacci extrinsic magnetized plasma multilayer
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Chittaranjan Nayak
    更新日期:2020-01-16
  • Novel D-A-D conjugated polymers based on tetraphenylethylene monomer for electrochromism
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Fuhan Liu; Zhongfei Cong; Guang Yu; Haijun Niu; Yanjun Hou; Cheng Wang; Shuhong Wang
    更新日期:2020-01-16
  • Optical linearity and bandgap analysis of Erythrosine B doped in polyvinyl alcohol films
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    E.F.M. El-Zaidia; H.A.M. Ali; Taymour A. Hamdalla; A.A.A. Darwish; T.A. Hanafy

    Polyvinyl alcohol (PVA) has utilized in various fields of industry. PVA has been chosen as a host matrix and then doped with Erythrosine B dye (EB) with different concentrations of EB by using casting procedure. The linear optical properties have been studied and it found that the refractive index of PVA that contains 4 wt % of EB dye decreased by 18% with respect to that obtained for the pure sample. Also, the energy gap of PVA doped samples was studied and found three kinds of interband. The calculated nonlinear properties for pure and doped PVA samples were investigated. The calculated values of the third-order susceptibility, χ(3), and nonlinear refractive index, n2, are decreased by EB doped and the sample doped by 4 wt % of EB has the lowest value of χ(3) and n2. The obtained values of the refractive index candidate our synthesized materials to participate in light-emitting diodes and images sensor.

    更新日期:2020-01-16
  • Flexible thin film ceramics for high temperature thermal sensing applications
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Makunda Aryal; Stephen W. Allison; Kathy Olenick; Firouzeh Sabri
    更新日期:2020-01-16
  • Preparation and spectroscopic studies of PbI2-doped poly(methyl methacrylate) nanocomposites films: Dielectric and optical limiting approach
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    S. Abd El-Mongy; M.I. Mohammed; I.S. Yahia

    In this work, a solution casting method was used to prepare the PbI2/PMMA nanocomposites films. XRD was used to achieve structural characterizations. An increase in an amorphous hump was showed after doping with PbI2 nanostructured. The spectra of FTIR were evaluated between (4000–400 cm−1). The carbonyl stretch band at 1754 cm−1 shifted to higher wavenumber shows the electrostatic interaction between PbI2 and the oxygen of the carbonyl group. Nanocomposites films were identified by scanning electron microscope. The optical UV–Vis–NIR aspects of the nanocomposite films were determined. Increasing the concentration of PbI2 in the investigated samples caused the energy gap to be decreased. Such adjustments in the optical characteristics of the PMMA sample are because of the interaction between the PMMA matrix and the PbI2 nanoparticles. AC electrical conductivity and dielectric properties were studied at room temperature. The dielectric constant increases with increasing the concentration of PbI2. Optical limiting was evaluated and investigated for PbI2/PMMA nanocomposites and the He–Ne and green lasers power was reduced by increasing PbI2 contents. The PbI2/PMMA nanocomposites are promising candidates for solar cells, electronic/optoelectronic devices, and CUT-OFF laser filters.

    更新日期:2020-01-16
  • Sb4O5Cl2 for 34th-order-harmonic mode locking
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Shu-yuan Lv; Ya-xin Chen; Xiao-hui Li; Wen-feng Luo; Ya-min Wang; Wen-xiong Xu; Abdul Qyyum; Han Zhang

    Due to the excellent electrochemical characteristics, Sb4O5Cl2 has been potentially used in flame retardant, catalyst, and anode materials, etc. At the same time, it has broad application prospects in optics and optoelectronics because of its strong inoxidizability, high damage threshold and relatively high-photoelectric conversion efficiency. However, the application of Sb4O5Cl2 in ultra-fast photonics has not been reported so far. In this work, the structure characteristic and nonlinear optics property of Sb4O5Cl2 have been systematically studied. The result indicates saturation intensity and modulation depth are 402.5 MW/cm2 and 1.3%, which prove Sb4O5Cl2 could be utilized as a saturable absorber (SA) in ultrafast photonics. Especially, harmonic mode-locking with 850-fs pulse duration, 2.86-nm 3-dB bandwidth, 202.3-MHz maximum repetition rate in optical communication region is generated based on a tapered fiber incorporated with Sb4O5Cl2 for the first time to our knowledge. This work opens novel avenues toward optoelectronics device based on Sb4O5Cl2 in the fields of optical modulation, optical detection and optical communication, etc.

    更新日期:2020-01-16
  • Effect of SiO2 on the sintering of cerium-doped lutetium oxyorthosilicate
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Olivia A. Graeve; Arash Yazdani; James P. Kelly; Raghunath Kanakala; James Tinsley
    更新日期:2020-01-16
  • Defects and symmetry influence on visible emission of Bi3+ Co-doped CeO2:Eu3+ phosphor
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Liyuan Sun; Yongjun Tan; Dewei Li; Hongli Du; Dongcai Guo
    更新日期:2020-01-16
  • Study on structural and optical properties of Mn-doped ZnO thin films by sol-gel method
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Xu Li; Xinghua Zhu; Kangxin Jin; Dingyu yang

    For ZnO, doping transition metal is one of the powerful tools to improve its photoelectric performance. In this study, Mn-doped ZnO thin films with various thickness and different doping concentration were synthesized by low cost sol-gel method. We systematically investigated structural and optical properties of Mn-doped ZnO with different concentrations and film thickness. Research showed that with the increase of Mn doping concentration, the crystallization of ZnO decreased, and the preferred orientation was weakened. Moreover, the ultraviolet–visible (UV–Vis) absorption coefficient rose as the energy gap (Eg) decreases and Urbach energy (EU) increases). In the intrinsic emission region below 380 nm and in the defect emission region of 440–600 nm, Mn-doped 1.5% ZnO showed the strongest emission, then the excessive doping would reduce photoluminescence of ZnO. However, in the defect emissions region of 380–440 nm, pure ZnO showed highest emission that decreased gradually with the increase doping concentration. Meanwhile, as the increase of film thickness, the crystallization properties of ZnO were improved, but there were more cracks which resulted in the decrease of UV–vis absorption coefficient, the decrease of Eg and the increase of EU). Meanwhile, the intrinsic emission enhanced and the defect emissions decreased.

    更新日期:2020-01-16
  • Study on electrochromic properties of TiO2 films under Co ion content fluctuations
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Bo Zhang; Guoyue Xu; Shujuan Tan; Chuyang Liu; Jianchao Zhang

    In this paper, the Co doped TiO2 film with satisfactory electrochromic performances was prepared by a sol-gel method. To study the Co-doped influence on the TiO2 film for the electrochromic performances, we respectively regulated the Co ion content to 0, 0.4, 0.8 and 1.2 at%. Due to the Co ions doped into the TiO2 film, the synthesized film led to the generation of the oxygen vacancies. From the results, when the optimal Co ion content is 0.8 at%, the improved switching time (the bleached time of 2.9 s and the colored time of 5.1 s) and the improved coloration efficiency (18.89 cm2/C) compared to the other samples are obtained. These results can be due to the enhanced Li+ diffusion coefficient and electric conductivity, which result in the increase of the electrochromic reaction activity and the reduction of the optical band gap in colored state to improve the transmittance modulation. Thus, the new film can be a competitive electrochromic material to enhance the performances of the electrochromic device.

    更新日期:2020-01-16
  • Semiconductor host for designing phosphors for modification of solar spectrum
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    P.K. Tawalare; P.D. Belsare; S.V. Moharil
    更新日期:2020-01-16
  • Luminescent carbon quantum dots/nanofibrillated cellulose composite aerogel for monitoring adsorption of heavy metal ions in water
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Zihui Song; Xueqi Chen; Xinchao Gong; Xing Gao; Qian Dai; Tat Thang Nguyen; Minghui Guo
    更新日期:2020-01-16
  • Single-mode square-grid MOFs with enlarged mode field intended for the middle infrared
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Elena Korsakova; Anastasia Yuzhakova; Alexandr Lvov; Dmitrii Salimgareev; Alexandr Korsakov; Liya Zhukova

    In this paper, we modeled and fabricated a single-mode microstructured fibre (MOF) based on the solid solution crystals of AgBr–TlI and AgBr–TlBr0.46I0.54 systems. For this purpose, we gained the refractive index dispersion of the given systems in the wavelength range of 19–25 μm. It served as a basis for fibre simulations. The obtained MOF model was 700 μm in diameter; it included 200-μm central insert and 40 quasi-square peripheral inserts with the cross-section of 20 × 20 μm and the pitch of 80 μm and operated in a single-mode regime within the wavelength range of 22–25 μm, while the transmitting range was 2.5–25 μm. It possessed an enlarged mode field when compared to a corresponding single-mode step-index fibre (SIF). This MOF was fabricated using a method, which combines hot pressing and extruding. It was shown that the fundamental mode is tightly confined in the fibre core region. The developed MOF structure may be suitable for producing outputs, splitters, and couplers for various types of solid-state lasers based on semiconductors and gas steam lasers, including ones deployed in a harsh environment.

    更新日期:2020-01-16
  • Energy transfer and spectroscopic properties of Cr3+/Yb3+ co-doped TeO2–ZnO–La2O3 tellurite glasses under different wavelength excitation lights
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Ho Kim Dan; Nguyen Minh Ty; Tran Duy Tap; Dai-Nam Le; L.T. Vinh; Dacheng Zhou; Jianbei Qiu

    In this paper, the upconversion/downconversion (UC/DC), visible (VIS) and near-infrared (NIR) emissions of Cr3+/Yb3+ co-doped TeO2–ZnO–La2O3 (TZL) tellurite glasses under different wavelength excitation lights were investigated. The CIE 1931 chromaticity coordinates for UC emission of Cr3+/Yb3+ co-doped TZL tellurite glasses under different excitation wavelengths were also investigated. Through the energy transfer (ET) and cooperative energy transfer (CET) processes from Cr3+ to Yb3+ and the combination of Cr3+-Yb3+ lead to the intensity of UC-, DC-, VIS-, NIR-emissions of Cr3+/Yb3+ co-doped TZL tellurite glasses significantly increased. Under different wavelength excitation lights, the optimal concentration of Yb3+ for the UC-, DC-, and VIS- emissions of Cr3+/Yb3+ co-doped TZL tellurite glasses is different. In addition, the ET, CET processes between Cr3+ and Yb3+ are also proposed and discussed.

    更新日期:2020-01-16
  • Novel blue emitting Tm3+ activated lanthanum molybdate: Investigations on luminescence behaviour and Judd-Ofelt theoretical analysis
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Kukku Thomas; Dinu Alexander; Linju Ann Jacob; P.R. Biju; N.V. Unnikrishnan; Cyriac Joseph
    更新日期:2020-01-16
  • 更新日期:2020-01-16
  • Spectroscopy and non-linear optical properties of DNA - Bilberry complex
    Opt. Mater. (IF 2.687) Pub Date : 2020-01-16
    Ana-Maria Manea-Saghin; Carla-Cezarina Pădureţu; François Kajzar

    Natural extracts are getting more attention due to the fast degradability rate and low toxicity. In this paper the obtained results for the complex based on deoxyribonucleic acid biopolymer with bilberry (BBE) natural extract are presented and discussed. The interaction between the two materials (DNA-BBE complex) was evaluated by measuring the linear optical properties using UV–Vis and fluorescence spectral methods. Furthermore, the DNA-BBE complex was used for non-linear optical (NLO) properties investigations of the obtained thin films on glass substrate by spin-coating technique. Also, the optical damage threshold of the studied DNA-BBE complexes was measured in order to check their potentiality and interest for application in photonics.

    更新日期:2020-01-16
  • 更新日期:2020-01-16
  • Judd-Ofelt analysis and crystal field calculations of Er3+ ions in new oxyfluorogermanotellurite glasses and glass-ceramics
    Opt. Mater. (IF 2.687) Pub Date : 2019-12-31
    Hayat Zanane; Matias Velázquez; Dominique Denux; Jean-René Duclère; Julie Cornette; Aïcha Kermaoui; Hamid Kellou; Michel Lahaye; Sonia Buffière
    更新日期:2019-12-31
  • Fabrication and physicochemical characterization of g-C3N4/ZnO composite with enhanced photocatalytic activity under visible light
    Opt. Mater. (IF 2.687) Pub Date : 2019-12-31
    Abinaya Mathialagan; Muthukumaran Manavalan; K. Venkatachalam; Faruq Mohammad; Won Chun Oh; Suresh Sagadevan

    The present study deals with the synthesis, characterization and photocatalytic activity of g-C3N4/ZnO composite towards the degradation of significant dyes like Malachite green (MG), Rhodamine-B (Rh–B), Congo red (Con-R), and Red ink (RI) solution. For the synthesis of the g-C3N4/ZnO composite, we have adopted the chemical precipitation method where the composite was thoroughly analyzed for the crystallinity, optical performance, and morphology by making use of the instrumental methods like powdered X-ray diffraction (PXRD), Fourier transform–infrared spectroscopy (FTIR), UV–Vis diffuse reflection spectroscopy (UV–Vis), Transmission electron microscopy (TEM), Atomic force microscopy (AFM), and thermogravimetric (TGA) analysis. It was found from the PXRD and TEM analysis that the composite maintains hexagonal wurtzite phases for the ZnO and g-C3N4 compounds, while the UV–Vis spectrum confirmed that the composite's absorption edge is getting shifted to the lower energy and wavelength region as compared to ZnO. On testing the photocatalytic activity under the UV light towards the dye degradation, the g-C3N4/ZnO composite is indicated to have significant performance and thereby supporting the synergistic impact of each component. The observation of such activity in the g-C3N4/ZnO composite can be investigated to be due to the composite's enhanced stability in the aqueous solution (supported by the lower amounts of Zn2+), in addition to the improved electron-hole separations and synergistic photocatalytic mechanism between ZnO and g-C3N4.

    更新日期:2019-12-31
  • Preparation and promising application of novel LaFeO3/BiOBr heterojunction photocatalysts for photocatalytic and photo-Fenton removal of dyes
    Opt. Mater. (IF 2.687) Pub Date : 2019-12-31
    Sitao Guan; Hua Yang; Xiaofeng Sun; Tao Xian

    Herein we have designed and fabricated a new type of LaFeO3/BiOBr heterojunction photocatalysts with Z-scheme charge transfer mechanism. The composite photocatalysts were constructed by coupling LaFeO3 nanoparticles with BiOBr microplates. Various advanced characterization techniques (e.g., SEM, TEM, XRD, UV–vis DRS, XPS, PL spectroscopy, FTIR photoelectrochemical measurements) were employed to elucidate the structures, micro-morphologies, element/composition valence states, optical absorption properties, surface functional groups and electron/hole pair separation behavior of the prepared LaFeO3/BiOBr photocatalysts. The photocatalytic and photo-Fenton degradation activities of the as-prepared LaFeO3/BiOBr photocatalysts were investigated by decomposing rhodamine B (RhB) aqueous solution, where simulated sunlight was used as the light source. Among the samples, the 20%LaFeO3/BiOBr composite photocatalyst manifests the highest photocatalytic degradation performance for RhB (η = 98.2% for 30 min reaction). The photodegradation activity of 20%LaFeO3/BiOBr is determined from the reaction rate constants to be about 21.0 and 1.3 times as large as that of bare LaFeO3 nanoparticles and BiOBr mcroplates, respectively. Furthermore, by adding an amount of H2O2 in the reaction solution, the photo-Fenton decomposition performances of the LaFeO3/BiOBr photocatalysts can be further enhanced. Z-scheme electron transfer process and photo-Fenton synergistic mechanism were used to explain the improved photodegradation and photo-Fenton degradation performances of the LaFeO3/BiOBr heterojunction photocatalysts.

    更新日期:2019-12-31
  • Transparent Y0.16Zr0.84O1.92 ceramics sintered from co-precipitated nanopowder
    Opt. Mater. (IF 2.687) Pub Date : 2019-12-31
    Penghui Chen; Qiang Liu; Yagang Feng; Xiaoying Li; Xiaopu Chen; Yumin Liu; Jiang Li

    Y0.16Zr0.84O1.92 transparent ceramics were successfully fabricated by air pre-sintering combined with HIP post-treatment from the nanopowder synthesized by the co-precipitation method. Fine and low-agglomerated Y0.16Zr0.84O1.92 powder with the average particle size of 14.8 nm was obtained by calcining the precursor at 800 °C for 4 h. The influences of pre-sintering temperature on the microstructure and optical quality of Y0.16Zr0.84O1.92 ceramics were investigated. It is found that the relative density of pre-sintered Y0.16Zr0.84O1.92 ceramics increases from 82.1% to 96.1% and the average grain size increases from 0.6 μm to 6.0 μm with the pre-sintering temperature increasing from 1250 °C to 1500 °C. The Y0.16Zr0.84O1.92 ceramic sample pre-sintered at 1300 °C for 2 h and HIP post-treated at 1800 °C for 3 h without sintering additives exhibits the best transparency. In-line transmittance of Y0.16Zr0.84O1.92 ceramics with the thickness of 1.0 mm reaches 72.4% at 800 nm, which is near to the theoretical transmittance.

    更新日期:2019-12-31
  • Saturable absorber incorporating graphene oxide polymer composite through dip coating for mode-locked fiber laser
    Opt. Mater. (IF 2.687) Pub Date : 2019-12-28
    E.K. Ng; K.Y. Lau; H.K. Lee; M.H. Abu Bakar; Y. Mustapha Kamil; M.F. Omar; M.A. Mahdi

    Fabrication of microfiber saturable absorbers (SA) is a tedious process. This work demonstrates a simplified method of microfiber SA fabrication by integrating graphene oxide/polymethylsiloxane (GO/PDMS) using dip-coating technique. The idea is to enhance light-matter interaction between graphene and propagating light modes within the microfiber by enhancing the binding strength and proximity of the graphene-polymer composite to the microfiber. The implementation of GO/PDMS SA in an erbium-doped fiber laser cavity has successfully generated ultrashort pulses with pulse duration of 629 fs in the C-band emission region. The success of this work contributes to better insight towards simplifying the fabrication technique of microfiber SAs.

    更新日期:2019-12-29
  • Efficient deep blue emitter based on carbazole-pyrene hybrid for non-doped electroluminescent device
    Opt. Mater. (IF 2.687) Pub Date : 2019-12-28
    Ting Zhang; Jieyang Ye; Ansheng Luo; Di Liu
    更新日期:2019-12-29
  • Analysis of terahertz waveguide properties of Q-PCF based on FEM scheme
    Opt. Mater. (IF 2.687) Pub Date : 2019-12-27
    Bikash Kumar Paul; Kawsar Ahmed

    A novel photonic crystal fiber in quasi pattern (Q-PCF) is designed and proposed for terahertz wave (T-wave) guidance. A cyclic olefin copolymer (COC) has been used as the bulk material of the proposed fiber. The proposed Q-PCF is introduced here for T-wave propagation, scaling from 0.8 to 2.40 THz. It is noted that, a low effective material loss (EML) of 0.038 cm−1 is obtained at working frequency f = 1 THz. It leads to a reduction in bulk absorption loss of 81% at the same working frequency. Moreover, some essential optical guiding parameters such as confinement loss, dispersion, modality, power fraction and effective mode area are also examined briefly. The fabrication of the proposed PCF is simple as it contains only air holes of circular shape. It is anticipated that the mentioned Q-PCF terahertz waveguide will provide a significant improvement over existing designs.

    更新日期:2019-12-29
  • Reduction of Sm3+ and Eu3+ ions-co-doped Al2O3–SiO2 glasses and photoluminescence properties
    Opt. Mater. (IF 2.687) Pub Date : 2019-12-27
    Ho Van Tuyen; Masayuki Nogami; Le Xuan Hung

    The reduction process of Sm3+ and Eu3+ ions doped in Al2O3–SiO2 glasses and the energy transfer phenomena between Sm2+ and Eu2+ ions were investigated. When the glass was heated with H2 gas, the H2 gas molecules diffused through the glass structure, followed by the reduction of Sm3+ to Sm2+ without forming AlOH bonds, whereas the Eu3+ ions reduced and formed AlOH bonds. The activation energy for the H2 gas diffusion in Sm3+-doped glass was higher than that of Eu3+-doped glass and the reduction of Sm3+ ions was suppressed as the Eu2O3 content increased. The photoluminescent properties caused by the energy transfer between Eu2+ and Sm2+ ions were also examined. The energy of the Eu2+:4f7 → 4f65 d1 transition effectively transferred to excite the Sm2+: 4f6 → 4f55 d1 transition, resulting in strongly enhanced emission intensities of the Sm2+: 5D0→7FJ transitions.

    更新日期:2019-12-29
  • The effect of mixed solvents on solute-solvent interactions and bulk growth of 3,4-diamino benzopheone: A novel benzophenone derivative for NLO applications
    Opt. Mater. (IF 2.687) Pub Date : 2019-12-26
    S. Usharani; J. Judes; V. Natarajan; M. Arivanandhan; P. Anandan; Dmitry A. Vorontsov; Mikhail O. Marychev

    Growth of bulk organic NLO crystals is a stupendous task in the field of crystal growth because of its remarkable properties such as better NLO efficiency and rapid response with light due to presence of delocalized electrons than inorganic materials, which could be implemented in the field of photonics. Attempts were made in growing bulk single crystal of novel benzophenone derivatives. Being one of the BP derivatives, 3,4-Diaminobenzophenone (3,4-DABP) was selected and grown as a bulk crystal by slow evaporation growth technique from a mixture of solvents of ethanol and o-xylene in the ratio of 1:3 at ambient temperature. Grown crystals were subjected to characterization studies like single crystal XRD, powder XRD, FTIR analysis, TG/DTA, UV–Vis NIR spectroscopy, Vicker's microhardness testing and NLO studies to reveal their structural, thermal, mechanical and optical properties. Powder XRD studies indicated the pure crystallinity nature of the grown crystals. The presence of various functional groups were analysed from FTIR spectrum. Optical studies revealed that the material can be used in photonics as optical filters. Microhardness study revealed that 3,4-DABP belongs to soft material and also exhibit Reverse Indentation Size Effect (RISE). SHG study confirmed that the frequency conversion efficiency of the crystal 3,4-DABP is 2.3 times that of KDP crystal.

    更新日期:2019-12-27
  • Diameter-selected single-walled carbon nanotubes for the passive Q-switching operation at 2 μm
    Opt. Mater. (IF 2.687) Pub Date : 2019-12-26
    Xiaodong Zhang; Hongwei Chu; Ying Li; Shengzhi Zhao; Dechun Li

    In this paper, we proposed the diameter-selected single-walled carbon nanotubes (SWCNTs) via the simple liquid phase separation for the pulsed 2 μm laser operation as the saturable absorber (SA). The nonlinear absorption properties of the prepared SWCNTs based SA at 2 μm were investigated. The modulation depth and the saturation intensity were 8% and 6.5 kW/cm2, respectively. By employing the diameter-specified SWCNTs SA, a stable passively Q-switched Tm:YLF laser was demonstrated at 2 μm for the first time. The maximum repetition rate of 35.9 kHz and the shortest pulse duration of 920 ns were achieved with the output coupler of T = 3%. The experiment results indicated that the diameter selection of SWCNTs could be a promising method to improve the Q-switching characteristics.

    更新日期:2019-12-27
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