A new slab configuration is designed based on the traditional Yb:YAG Total-Reflection Active-Mirror (TRAM) slab laser. The grad-doping method is proposed to improve the pump uniformity of the gain medium. A thermal analysis model is established by the ray-tracing software and finite element method. The thermal effects of the uniform doping medium and gradient doping medium are investigated according

A discrete model governing a system of cold bosonic atoms in zig-zag optical lattices in quantum optics was proposed in the literature. In an analog to this model, a continuum model is, here constructed. The resulting equation is a nonlinear Schrodinger equation NLSE with drift force and linear growth. Exact solutions of this equation are obtained. To this issue, a new transformation that allows to

In this paper, we investigated the influence of Semiconductor Saturable Absorber Mirror (SESAM) parameters on pulse evolution of passively mode-locked fiber laser at different repetition rates. Based on the Nonlinear Schrodinger Equation, the mode-locked process of the SESAM passively mode-locked fiber laser and the pulse evolution were simulated. Furthermore, the impact of modulation depth of a SESAM

An evaluation model for optimizing system parameters was established in this study using longitudinal-mode pre-lase selection technology. By solving the rate equation and calculating the evaluation function, we determined the evaluation efficiency of a single-longitudinal-mode operation using this scheme. The optimal condition for the characteristics of the single-longitudinal Q-switched laser was

In this article, we have proposed and demonstrated a new approach to implementing microwave photonic filter (MPF) with switchable, tunable and reconfigurable passbands based on a multi-wavelength fiber laser (MWFL) cooperating with a fiber Mach–Zehnder interferometer (FMZI). An EDFA and an SOA have been employed as a hybrid gain medium in the laser cavity, to suppress the homogeneous broadening of

In part I of this work, we provided a general model for optically induced thermal aberrations due to high power structured light pumps, highlighting the implications for arbitrary structured probes. We showed how the thermal effects impact on various structured light fields, and illustrated how to mitigate these effects using the structure of light as a new degree of freedom for control. Here, in part

A one-dimensional premixed ethylene–air flame is investigated regarding the presence of various combustion intermediates and products relevant for the formation of carbonaceous particles for various equivalence ratios and spatial positions using in situ UV–Vis absorption spectroscopy. A laser driven light source in combination with a fast spectrometer allow to record absorption spectra at a high rate

We perform thermal lens and thermal mirror Z-scan experiments to study the photothermal properties of semiconductors. We fix the sample’s position, facilitating the alignment procedure and the experiment’s interpretation. By scanning the lens, which focuses the pump beam, we obtain the Z-scan signature. A diode laser at 1064 nm provides the probe beam for the thermal lens experiment, while a Helium–Neon

In this article, the authors are presented the work on the evaluation of structural and third-order nonlinear optical (NLO) properties of lead (Pb)-doped zinc oxide (ZnO) thin films. The nano structured Zn1-xPbxO thin films were lay down on the glass substrate at an heating temperature of 350 °C with different Pb-doping concentration (‘x’ ratios of 0, 0.01, 0.05 and 0.1 wt. % of Pb) using the standard

In this work, we have investigated six different in situ optical contactless temperature probing methods for cryogenic Yb:YAG systems. All the methods are based on variation of fluorescence spectra with temperature, and they either look at the width of the emission line, the ratio of the emission intensity at different wavelengths and to the overall spectral change at selected wavelength intervals

Laser-induced fluorescence of a “tracer” is a sensitive technique for imaging liquid fuel films that can be important in energy conversion devices such as internal combustion engines. This work investigates the fluorescence of potential tracers dissolved in liquid iso-octane at elevated pressures and temperatures after nanosecond pulsed irradiation at 266 nm. Most experiments were on fluorescence from

In this work, a facile spray-assisted perfume atomizer technique was used to prepare CdO and Fe-doped CdO (CdO:Fe) thin films with varying concentrations of Fe (1, 3, and 5 wt%). The deposited films were characterized using different analytical techniques to realize the structural, morphological, optical, electrical, and photosensing properties. From X-ray diffraction (XRD) results, the CdO and CdO:Fe

This paper presents a theoretical study on the generation of optical frequency combs (OFCs) using direct modulation of semiconductor laser. Influence of gain suppression on characteristics of the generated OFCs is investigated. The study includes intensive and comprehensive investigations of the temporal and spectral characteristics of the generated OFCs as a function of the gain suppression over a

We study the quantum dynamics of the two impurities in a trapped quasi-one-dimensional Bose–Einstein condensate (BEC). We explore the effect of impurity-BEC and impurity-impurity interaction strengths on the dynamics of impurities inside the Bose–Einstein condensate. By studying the auto-correlation function of impurities and the BEC, we analyze and quantify the trapping of impurities inside the BEC

In this paper, we use Fresnel diffraction from a phase step in transmission to measure the diffusion coefficient in a transparent liquid. A transparent glass plate immersed vertically in a cell containing two diffusing liquids makes a phase step in transmission. When it is illuminated by a parallel beam of light, the diffraction pattern is formed on a screen perpendicular to the direction of the light

In the analysis of complex stratigraphical structures like painted artefact, infrared (IR) techniques can provide precious information about elements hidden under superficial layers of the artwork, such as pictorial features and structural defects. This paper presents a novel complementary use of reflectographic and thermographic techniques for the survey of three baroque paintings, preserved at the

For fiber-coupled green laser-diode pump beam, a simple model was proposed to calculate the average outputs. Then we presented a direct-pumping continuous-wave Ti:Sapphire laser producing an optimized output of 3.8-W with green diodes. It was the highest output of this kind reported so far corresponding to an optical/optical conversion efficiency of 11.5% and a high slope efficiency of 15.7% at 810 nm

A laser wavelength meter was calibrated to ±1 MHz 1\(\sigma\) using transitions in molecular iodine at around 700 nm, where precise experimental measurements of iodine lines are sparse. Two saturation absorption spectroscopy systems were used to measure and characterize the R(118)(2-8) a10, R(54)(3-9) a1, and P(48)(3-9) a15 hyperfine lines of molecular iodine near 700 nm. The transition frequencies

As a means of increasing the temperature range of high-precision measurements for aerosol phosphor thermometry (APT), the co-doped Ce,Pr:LuAG phosphor was investigated for use with simultaneous Pr3+-scattering-referenced APT (SRAPT), Ce3+-SRAPT, and co-doped APT techniques. Phosphor characterization was performed in a heated air jet at atmospheric pressure, and APT performance was estimated for the

In the multirotation computational imaging system (MRCI), the rotation angle of the cylindrical lens is vital to the reconstruction results from the experimental data. However, the rotation angles of the cylindrical lens are hard to be measured directly and precisely. High-precision angle evaluation methods are urgently needed to improve the recovered images. This paper proposes an angle estimation

In this article, a one-dimensional asymmetric photonic crystal (PC) structure based on the magnetized and non-magnetized plasma and non-linear materials is designed, and the features of the PCs are simulated and analyzed by the transfer matrix method. We realize the optical reconfigurable bistable (ORB) absorption of one-dimensional PCs and discover that due to the asymmetry of the spatial structure

This paper considers the calculation of the nonlinear losses induced in a circular aperture enlighten by a focused Gaussian beam (GB) subject to optical Kerr effect. Such a problem known since a long time typically requires the numerical calculation of a diffraction integral which becomes rapidly cumbersome in the case of repetitive applications. Alternatively, we propose a new simple modelling completely

The transmission characteristics of dielectric-coated metallic hollow waveguides (DMHW) are simulated by means of Ray Model, Transmission Line Model, and Finite Element Analysis methods. By comparing the simulation results in mid- and far-infrared, terahertz and millimeter wavelength bands, the range of application and deviation analysis of three simulation methods are presented. Limitations of each

With the rapid development of optoelectronic fibers of multi-materials and structures, coupling between the optoelectronic fibers and the conventional optical fibers with high transmission is desirable. In this article, we propose a mode coupler to facilitate the transmission of electromagnetic wave from a dielectric fiber to a simple metal-core optoelectronic fiber in the terahertz regime. The coupler

The Fox-Smith mirror (FSM) has long been used in a three-mirror laser cavity arrangement for forcing the laser oscillation on a single-longitudinal mode. However, its transverse properties are very little studied, and we report three interesting transverse features. First, the FSM gives the possibility to change the order p of the oscillating radial Laguerre–Gaussian LGp0 mode by adjusting the microscopic

Two-wavelength and two-color laser-induced incandescence (2λ–2C-LII) was used to study the absorption properties of three types of cold soot of different maturity from a mini-CAST soot generator. LII fluence curve analysis allowed for estimating absorption wavelength dependence in terms of dispersion coefficients ξ by the use of two excitation wavelengths (532 and 1064 nm). The estimated ξ (based on

A correction to this paper has been published: https://doi.org/10.1007/s00340-021-07642-5

The pure P2(8) line radiation of chemical hydrogen fluoride (HF) laser which can be weakly absorbed by atmosphere was generated using an absorbed module in a line-selected cavity. A numerical model of laser gain was investigated to predict and optimize the laser performance. An experimental verification was carried out in a compact continue wave (cw) tunable chemical HF laser device. It is found that

A correction to this paper has been published: https://doi.org/10.1007/s00340-021-07611-y

We propose a method for predicting the concentration of a functional ingredient, procyanidin, in apple using Raman spectroscopy in combination with multivariate calibration analysis. A regression model was constructed by partial least-squares (PLS) regression using the collected Raman spectra and the procyanidin concentrations measured by high-performance liquid chromatography (HPLC). Four different

We propose and experimentally investigate a spiral-polished single-multi-single-mode (SP-SMS) fiber sensor for the simultaneous measurement of strain and temperature. This special spiral shape on a multimode fiber is fabricated by a high-frequency CO2 laser, which excites higher order cladding modes in the interference process and leads to high strain sensitivity. Experimental results show that the

We study a coherently driven semiconductor laser cavity containing a single quantum dot(QD) (as gain medium) with optical feedback under Markovian approximation. We have obtained coupled operator equations for the model Hamiltonian using standard input-output formalism of cavity-QED and have found that these equations do not have any finite steady state solutions. We have also used an exact numerical

We show that negative resonant modes with an inverse relationship between the wavelength and the cavity length can be excited in a hyperbolic metamaterial slot cavity (HMMSC) in addition to positive resonant modes. The observed negative resonant modes in an HMMSC are in sharp contrast to that observed in a metal slot cavity. We analyze the dynamics of the excited negative resonant modes in the visible

The 8 m laser interferometer prototype facility is currently being constructed at the Institute of Mechanics, Chinese Academy of Sciences in Beijing, China. It aims to perform laser interferometer experiments and pico-meter precision detection and calibration for Taiji pathfinder mission. The seismically isolated ground and passive vibration isolation are interconnected and the optical benches are

In this study, a metamaterial comprising an N-type strip (NS) and a double split-ring resonator (DSRR) has been investigated, which is the first to exhibit the broadband electromagnetically induced transparency (EIT) effect and dual-band transmission-type polarization conversion under microwaves. The transmittance coefficient reaches a maximum value of 0.94 at 13.10 GHz, while the bandwidth of the

A new spectroscopic method using a multimode tunable blue diode laser and direct absorption spectroscopy is developed to detect trace amount of nitrogen dioxide (NO2) gas. The method produces distinctive signatures for NO2 absorption that are utilized to accurately measure the gas concentration. The NO2 signatures are obtained by measuring the transmission through a calibrated NO2 gas sample as a function

Quantum-optical technologies based on parametric light down-conversion are not yet applied in the terahertz frequency range. This is owing to the complexity of detecting single photons in the terahertz frequency range and the strong entanglement of modes of optical–terahertz biphotons. This study investigates the angular structure of scattered radiation generated by strongly non-degenerate parametric

An extraction method for the equivalent electromagnetic parameters (EEP) of grading honeycomb absorbing materials (GHAM) is proposed based on the asymmetric property of GHAM, EEP was modified by gradient factors related to its physical parameters in this paper. Considering that the strength of electromagnetic wave loss is dominated by the imaginary part of the complex dielectric constant, the EEP extraction

We report on short pulse generation from a passively Q-switched Pr3+:LiYF4 laser operating at 640 nm. By reducing the cavity length and utilizing Co:MgAl2O4 as the saturable absorber, we obtain the shortest pulse durations from any Q-switched Pr3+ laser. Under pumping with a frequency-doubled optically pumped semiconductor laser at a wavelength of 479.05 nm we realized (8.5 ± 1) ns long pulses at a

The low reproducibility is the most critical obstacle to the wide commercial application of laser-induced breakdown spectroscopy (LIBS). In this work, to improve the sample-to-sample reproducibility of LIBS real-time analysis of coal calorific value, we applied the acoustic signal generated by the laser ablation as the reference signal for normalization. First, the correlation between acoustic signal

Acetylene black is a special type of carbon black, obtained from the thermal decomposition of acetylene. Acetylene flames enable the investigation of the soot optical properties. A reliable knowledge of the optical properties of acetylene soot is necessary for interpreting the optical measurements in flames and the development of acetylene black applications in industry. However, a wide variation in

Two-dimensional temperature measurements using filtered Rayleigh scattering (FRS) were performed in confined CH4/air swirl flames at atmospheric pressure. The investigated burner has a combustion chamber consisted of four quartz windows. The combustion chamber is 160 mm high with a square section of 50 × 50 mm2. Measurements were challenging due to the strong interference from the incident laser impinging

This work describes the diagnostic implementation and image processing methods to quantitatively measure diesel spray mixing injected into a high-pressure, high-temperature environment. We used a high-repetition-rate pulse-burst laser developed in-house, a high-speed CMOS camera, and optimized the optical configuration to capture Rayleigh scattering images of the vaporized fuel jets inside a constant

We developed a high-power dual-wavelength green pulsed laser that generates 528-nm and 535-nm laser pulses which overlap completely in time and space. Two single-frequency seed lasers of 1056 nm and 1070 nm are combined and amplified to 140 W through a series of ytterbium-doped fiber amplifiers including a rod-type fiber amplifier, and the amplified laser pulses of two wavelengths are frequency-doubled

Intra-cavity pumped Ho laser basing on the biaxial YAP host is investigated here for a direct LD pumped compact polarized 2.1 μm laser at room temperature, where the a-cut and b-cut Tm:YAP and Ho:YAP crystals were applied and placed with the same crystallographic orientation. The maximum output power of 2.47 W at 2118 nm was obtained for the b-cut Ho:YAP laser with a slope efficiency of 15.1%, which

The use of laser beams made up of ultrafast pulses for the processing of materials can be bothered by the consequences of optical Kerr effect (OKE) cumulated by the propagation through optical devices (windows, laser crystal, prisms, lenses, …). The latter are mainly a reduction of the intensity in the focal plane accompanied by a distortion of the temporal and spatial pulse shape. We present a comparative

A Tm3+:Y2O3 ceramic laser with the L-shaped cavity in-band pumped by a fiber laser at 1670 nm was studied in the CW and passively Q-switched regimes. The CW laser was tunable in the range between 2046 and 2054 nm. The output power reached up to 4.9 W and the average slope efficiency was 75% in the high-quality single-transverse-mode beam The highest CW output power in the multi-transverse-mode beam

The period (\(\wedge \)) of nanograting in sapphire varied from 320 to 398 nm with increasing the laser fluence, which is similar to the change trend of period of the near-subwavelength ripples previously observed on the material surface (\(0.4<\wedge / \lambda <1\)) (Huang et al. in ACS Nano 3:4062, 2009). The result shows that the interference of the incident laser with the plasma could take place

The conversion of transverse mode-locked (TML) laser beams from a Hermite-Gaussian (HG) to a Laguerre-Gaussian (LG) mode set using a cylindrical lens mode converter was demonstrated experimentally. By changing the spatial symmetry of the beams new spatio-temporal dynamics for TML lasers were enabled. In particular, the fast linear motion of an oscillating laser spot, generated by a TML laser based

Experimental and simulation studies show that a hexagonal array of polystyrene particles on a gold substrate, capped with gold semi-shells, results in increased optical confinement of the resonance modes in comparison with those for arrays without metallic substrate or capping. Well-ordered arrays of polystyrene beads were fabricated by convective deposition, a solution-based self-assembly process

In this study, we have designed and simulated a photonic crystal (PhC) nonlinear AND logic gate. First, a suitable photonic crystal ring resonator (PhCRR) structure is designed and simulated that can be used for obtaining the switching power intensity after applying the nonlinear Kerr effect. In this structure, GaAs dielectric rods have been used in the air. The plane wave expansion (PWE) method is

We experimentally characterize the positions of the diffraction maxima of a phase grating on a screen, for laser light at oblique incidence (so-called off-plane diffraction or conical diffraction). We discuss the general case of off-plane diffraction geometries and derive basic equations for the positions of the diffraction maxima, in particular for their angular dependence. In contrast to previously

A novel tunable terahertz metamaterials polarization converter (PC) is presented in this paper, whose operating band can be extended by the innovative band splicing technology (combine different PCs with different bands to make the bands splice together) and adjusted into a broadband absorber via adjusting the temperature. Four different units are combined to form a supercell and the phases can be

Genetic analysis is considered to be the ultimate diagnostic approach in many fields, e.g., in medicine for disease detection, in agricultural technology for food and feed authentication, in forensics, to name a few. Consequently, great interest is growing in developing sensitive and reliable analytical tools (biosensors) to identify whole DNA sequences, oligonucleotide fragments, or single-nucleotide

In this work the fabrication and characterization of As2S3 and erbium-doped As2S3 layers on Er:Ti:LiNbO3 channel waveguide amplifiers are reported and compared with Er:Ti:LiNbO3 channel amplifier for the first time to the author’s knowledge. We have first characterized a typical Er:Ti:LiNbO3 waveguide amplifier of 2.6 cm length and measured a small signal net gain of 2.5 dB for TM mode under 1470 nm

An efficient but simple scheme of an axicon-based resonator for tuning the spatial mode of high-power and high-order Bessel–Gaussian beams is proposed. This scheme is extended for two types of high-power lasers: continuous wave (CW) and Q-switched lasers. More importantly, the right axicon apex angle, the resonator optical length and the internal aperture diameter and its place inside the resonator

For stationary light fields, the degree of polarization (DOP) of light relates to the maximum correlation between two arbitrarily decomposed orthogonal electric field components at a space–time point. We generalize this understanding theoretically by showing a physically insightful connection between DOP and the two-time degree of coherence of electromagnetic fields. Further, by using a variable path

Er3+ doped tellurite glasses have been the subject of current research for potential applications in photonics. When compared with other glasses, these materials exhibit some valuable properties in the field of optical fiber amplification or laser radiation generation, such as a high refractive index, a broad photoluminescence band around 1550 nm, high chemical and thermal stability, high infrared

The characteristic parameters as well as self-generated electric and magnetic fields of Nd:YAG laser (532 nm, 10 ns) ablated Al plasma have been measured by employing Langmuir, electric and magnetic probes, respectively. Plasma parameters such as electron temperature (\({T}_{e}\)) and electron number density (\({n}_{e}\)) as well as SGEMFs of Al plasma are measured as a function of laser irradiance

A fiber optic temperature sensor consisting of two cascaded high birefringence fiber loop mirrors (Hi-Bi FLMs) was proposed and experimentally demonstrated to enhance the temperature sensitivity and resolution by Vernier effect. The FSRs for the two Hi-Bi FLMs are designed to be slightly different to generate the Vernier effect. The working principle for the proposed sensor is analogous to Vernier-scale