This paper presents a laser-based absorption technique for measuring temperature and CO concentration in high-pressure shock tubes. Two fundamental vibrations of CO (v" = 0, P8, 4.73 µm and v" = 1, R21, 4.56 µm) were selected for high-temperature sensitivity with a reduced influence from pressure broadening compared to previous work. Single-pass absorption (80 mm path length) was measured with two

A cheap and efficient production of boron isotopes is important for providing further progress in nuclear engineering, semiconductor industry, and nuclear medicine. Motivated by this problem, we consider the \({\text {CO}}_{2}\) laser system designed to separate boron isotopes by the method of laser-assisted retardation of condensation. Values of the basic parameters for this system, such as an acceptable

The nonlinear imaging in laser beam propagation is investigated theoretically under the circumstance that the linear media in the optical path model have arbitrary negative or positive refractive index. Based on the linear diffraction theory and thin-medium approximation, the propagation is solved analytically. Numerical simulation results obtained by split-step Fourier method are also presented. It

This paper presents effect of reflection-induced optical feedback on the post-detection signal power in an intensity modulation-direct detection (IM-DD) fiber optic transreceiver. The detected signal power reduction depends on the reflectivity of the external reflector as well as on the reflectivity of the laser cavity output facet. In the present dual reflector system, any increase in FPLD end facet

A mid-infrared laser absorption sensing method has been developed to quantify gas properties (temperature, pressure, and species density) at MHz measurement rates, with application to annular rotating detonation rocket flows. Bias-tee circuitry is integrated with distributed feedback quantum cascade and interband cascade lasers in the \(4{-}5~\mu \hbox {m}\) range enabling diplexed radio frequency

We report the design and characteristics of a simple and compact mode-locked Er-doped fiber laser and its application to broadband cavity-enhanced spectroscopy. The graphene mode-locked polarization maintaining oscillator consumes less than 5 W of power. It is thermally stabilized, enclosed in a 3D printed box, and equipped with three actuators that control the repetition rate: fast and slow fiber

Ag@ZnO core–shell nanostructures, ZnO nanoparticles (NPs), and Ag NPs were synthesized by laser ablation in water using 8 ns, 1064 nm, and 50 mJ/pulse. The structural, morphological, componential, and optical properties of as-synthesized NPs were examined by X-ray diffraction, transmission electron microscopy, electron diffraction spectrum, and ultraviolet–visible absorption, respectively. The third-order

There is a method that presents for securing much information at the same time, which need not be restricted to a single image data. Based on ghost imaging, this paper proposes a new encryption algorithm: multi-image holographic encryption based on phase recovery algorithm and ghost imaging (PRA-GI). In the encryption process, first, multiple images are combined into one phase hologram image by phase

We report a fully stabilized self-referenced all-solid-state-laser frequency comb based on a home-built Kerr-lens mode-locked Yb:CaYAlO4 oscillator, which delivers ultrafast pulses with a pulse duration of 54 fs and an average power of 1.5 W. Free running carrier-envelope phase offset frequency (fceo) is observed with a signal to noise ratio of 40 dB at 100 kHz resolution bandwidth, which is phase-locked

A tunable terahertz gas laser is demonstrated with a germanium ealton served as the spectrum splitter. The germanium ealton is 1.2-mm thick and anti-reflection coated at 10.17 μm, giving good dichroic performance for infrared and far-infrared radiation. By tuning the incident angle of the germanium ealton, the transmittance of 95% at 9– 11 μm wavelengths and the reflectance of more than 70% at 180 – 500 μm

We report two-wavelength pump-probe measurements of the metastable state lifetime in a high-concentration erbium-doped fiber (EDF). The lifetimes under population inversion conditions are measured using a 980 nm pump laser and a 1.5 µm probe laser. The lifetime variation from the lifetime under low excitation conditions to that of a highly inverted population are calculated using a model derived from

We operate a fiber-based cavity with an inserted diamond membrane containing ensembles of silicon vacancy centers (SiV\({}^{-}\)) at cryogenic temperatures \(\ge 4~\)K. The setup, sample fabrication and spectroscopic characterization are described, together with a demonstration of the cavity influence by the Purcell effect. This paves the way towards solid-state qubits coupled to optical interfaces

We investigate the frequency-resolved intensity noise spectrum of an Yb-doped fiber amplifier down to the fundamental limit of quantum noise. We focus on the kHz and low MHz frequency regime with special interest in the region between 1 and 10 kHz. Intensity noise levels up to \(\ge\)60 dB above the shot noise limit are found, revealing great optimization potential. Additionally, two seed lasers with

Successful operations of quantum-logic-based \(^{27}\hbox {Al}^+\) ion optical clocks have been reported by several groups. But there are still several lingering issues. The first is the proper choice of logic ions, and the second is the proper quantum state identification methods. In this paper, the advantage of using \(^{25}\hbox {Mg}^+\) as the logic ion to ensure smaller time-dilation shift is

A polarization-maintaining (PM) fiber-coupled acousto-optic modulator (AOM) was used, in the present work, to tailor the stable 3.523 picosecond (ps) mode-locked pulses generated by an all PM fiber oscillator. The pulse clusters with 7.315 MHz, 731.5 kHz, and 73.15 kHz of repetition rate were obtained. The number of pulses in each pulse cluster could be adjusted from 1 to 6. Through the harmonic mode-locked

Compact nonlinear frequency conversion of a Y-branch distributed Bragg reflector (DBR) diode laser for alternating dual-wavelength laser emission at 532 nm is presented for the very first time. The developed light source, realized on a 5 × 25 mm2 micro-optical bench, is based on single-pass second harmonic generation of a 1064 nm Y-branch DBR diode laser in a periodically poled lithium niobate waveguide

Unfortunately, the first author name was incorrectly published in the original publication

It is crucial to understand the behavior of the optical properties of soot in the visible and near-IR spectral range to calculate the magnitude of their emission and absorption. Such information also helps in the development of diagnostic methods for soot. We measured the absolute value of the refractive index functions of soot nanoparticles E(m,1064) at a wavelength of 1064 nm, as well as the ratio

Terahertz (THz) air coherent detection is a broadband coherent detection technique, which has been used widely in the THz science and technology. In this paper, a frequency-dependent response function of THz air coherent detection is defined based on the nonlinear polarization of gas molecules induced by the ultrashort laser pulses and the THz pulses. Calculations show that the response function of

It is believed for a long time that optical quality of liquid gain-medium (dye solution) of high pulse-repetition-frequency dye laser is degraded by its turbulent flow but so far this belief is not verified by direct experiment. We have devised a novel experiment to study the exclusive effect of turbulent flow on the optical quality of the dye solution pumped by copper vapour laser. The experiment

The primary aim of this work was to study the diseased and healthy rice plant samples at the elemental and molecular level to get the proper understanding of the causes and the chemical changes occurred in the healthy rice grains with the infestation due to false smut disease. We have used microscopic and isolation methods to detect and identify the presence of the species of pathogen involved in the

Cadmium sulphide is known to have tremendous applications towards optoelectronic and nonlinear devices. Hence, here we have facilely casted the CdS films with diverse Se contents through low-cost spray pyrolysis technique. XRD study defends mono-phase formation of CdS having hexagonal system at all Se doping contents. Scherrer equation was employed to evaluate crystallite size in range of 15–25 nm

We present a new scheme to produce a tunable converge elliptical optical vortex (EOV) with a phase-only element: elliptical helical lens (EHL), which is studied theoretically and experimentally. As a result, the properties of converge EOVs can be controlled by adjusting the parameters of EHL. The topological charges of the EOVs can be directly read from the received intensity pattern. Because EHL is

Developing ultralow threshold nanolasers is a challenging task despite of their great potential for a variety of applications. This work proposes to combine the advantages of low loss of dielectric materials and tight confinement of field in slotted dielectric nanodisks with gain medium embedded to them and supported by metallic substrate, which generates anapole mode with a lifetime longer than for

A compact and ultra-wideband multimode interferometer (MMI)-based polarization beam splitter (PBS) is designed in a silicon-on-insulator (SOI) platform. A sub-wavelength grating (SWG) structure is employed in the multimode region to reduce the overall length of the structure and also increase its operating bandwidth. Instead of using the beat-length difference to separate the transverse electric (TE)

4.9–5.5 µm laser oscillations were observed in high-purity bulk terbium-doped Ge36Ga5Se59 glass pumped by pulsed 2.93 µm Er:YAG laser. This is the first evidence of laser action corresponding to 7F5–7F6 transition of Tb3+ ions and of mid-infrared lasing in chalcogenide glass host.

An optimized Back-Propagation network (BP network) based on Genetic Algorithm (GA) was introduced to construct bidirectional reflectance distribution function (BRDF) model. To verify the performance of GA-BP network, two different kinds of space target materials were used for experiment. Based on the experimental data, we used GA to simulate the undetermined parameters of a five-parameter BRDF model

The peculiarities analysis in design of compressors for negatively chirped optical pulses parametrically amplified in double-chirped regime up to 1 J in multi-cascade system is done. A comparative analysis of the spatio-temporal distribution of the pulses at the output of various compressor schemes with an internal telescope has been performed. The analysis has been carried out using two methods: calculating

Some industrial uses of living cells involve genetic engineering or modification of cell’s external properties. However, these techniques commonly have high financial costs, do not take advantage of the natural properties of the cells, and have few applications in the photonics area. As the first technological application of living liquid crystals, we propose an all-passive optical diode using Bacillus

We demonstrate here, for the first time to the best of our knowledge, the method of classification and identification of metals, metal alloys using the color CCD images of femtosecond (fs) laser-induced plasma emissions. The non-gated color CCD images of the plasma emissions were used to train the machine learning algorithm for identification. We have also compared the obtained results with the fs-laser-induced

We develop a theoretical model of multimode rate equation that accurately describes mode evolution mechanism of prelase Q-switched Pr3+:YLF single longitudinal mode (SLM). We find that it is important to consider the effect of gain difference when calculating the mode competition time accurately. We identify that there is an optimal parameter for the two step signal of acoustic-optic modulator which

Nanofibre-based optical cavities are particularly useful for quantum optics applications, such as the development of integrated single-photon sources, and for studying fundamental light–matter interactions in cavity quantum electrodynamics (cQED). Although several techniques have been used to produce such cavities, focussed ion beam (FIB) milling is becoming popular; it can be used for the fabrication

Within the framework of the second order of perturbation theory and the dipole approximation, we derived simple formulas describing the temporal dynamics of ultrashort laser pulse scattering in terms of the scattering tensor and the Fourier transform of the strength of the electric field in a pulse. This expression was used for description of resonant scattering of an ultrashort pulse by an atom. We

In this paper, absolute-phase total internal reflection heterodyne interferometry is proposed for measuring a full-field refractive index. In this method, an optical configuration of prism-based total internal reflection is used. If an electro-optical modulator is driven by a sawtooth wave with an amplitude lower than the half-wave voltage, heterodyne interferometric signals can be generated in segment

A large and tunable lateral shift in a prism coupling system with a superconducting YBa2Cu3O7 film is theoretically analyzed. The dip of the reflectivity and magnitude of the lateral shift can be controlled by the temperature of the superconducting film. The sign of the lateral shift can be determined by the thickness of the superconducting film. The position of the minimum reflection and maximum Goos–Hänchen

A long-term stable single-longitudinal-mode (SLM) all polarization-maintaining (PM) compound-ring cavity fiber laser is reported. The results show that the PM fiber's strong ability to resist the environment disturbance allows finely designing the length of each secondary cavity in real time according to the main cavity under the laboratory environment, and then the effective longitudinal mode spacing

For the first time, the UV inductive nitrogen laser was created with generation energy of 11 mJ and pulse duration 10 ± 1 ns (FWHM). Lasing was obtained on two lines with wavelengths of 337.1 and 357.7 nm. The generation energy distribution over the cross section had a shape of a ring with diameter and width of about 40 and 2 mm, respectively.

In this article, we set up a theoretical model to investigate the physical mechanism of circularly polarized (CP) high-harmonic generation (HHG) by two-color relativistic driving lasers (with one at fundamental and the other at second harmonic). The compression effect of the electron density profile and the boundary oscillating are responsible for the harmonic emission. Based on this model, the scaling

We report on the realization of a displacement sensor based on an optical nanofiber. A single gold nano-sphere is deposited on top of a nanofiber and the system is placed within a standing wave which serves as a position ruler. Scattered light collected within the guided mode of the fiber gives a direct measurement of the nanofiber displacement. We calibrated our device and found a sensitivity up to

Excess micromotion of trapped ions leads to several adverse effects, such as modulating the absorption spectrum, shifting the transition frequency, and causing extra motional heating of ions. Moreover, it is hard to deal with, if there is no rf null point in a Paul trap. In this paper, two methods are proposed to control these adverse effects introduced by excess micromotion. The first method can eliminate

The fringe pattern obtained by optical interference is susceptible to speckle noise, which causes the fringes to be blurred to some extent. It is a critical step to achieve fringe smoothness while removing speckle noise. In this paper, we propose a new variable image decomposition model TGV–Hilbert–Shearlet, in which low-density fringes, high-density fringes, and noise are described by the total generalized

A new fast sensor for simultaneous high temperature diagnostics (above 800 K) of nitrogen oxide (NO) concentration and gas temperature (T) was developed based on the spectral fitting of low-resolution NO UV absorption near 226 nm. The sensor was intended for process control in future low-carbon footprint heavy process industries using renewable powered electro fuels (e.g. H2, NH3) or plasma torches

Quantum vision is currently emerging as an interdisciplinary field synthesizing the physiology of human vision with modern quantum optics. We recently proposed a biometric scheme based on the human visual system’s ability to perform photon counting. We here present a light stimulus source that can provide for the requirements of this biometric scheme, namely a laser light beam having a cross section

In this work, a novel single-shot pump-probe technique based on mirror array is proposed, which can be used to investigate the dynamics of nonlinear absorption with a single-shot femtosecond laser. Using this unique mirror array, the dispersion of femtosecond pulse laser caused by time delay can be avoided and the delay time can be increased effectively. Additionally, the energy requirements of the

The present paper proposes a novel denoising method to suppress multi-source noise and enhance the signal-to-noise ratio (SNR) of the phase-sensitive optical-time-domain reflectometer (Ф-OTDR). The method is based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and the interval thresholding. Firstly, the CEEMDAN is applied to the vibration signals to obtain a series

To achieve a high-sensitivity surface plasmon resonance sensor, a sensor based on Ag-MgF2 grating was designed and fabricated. A suitable-thickness MgF2 was suggested to prevent the oxidation of silver while avoiding reducing its plasmonic properties. The combination of an interference lithography approach, the material used for the fabrication of grating, and angular interrogation method led to a

Single crystals of pure and crystal violet (CV) dye-doped anthracene single crystals have been synthesized by solvent evaporation technique utilizing chloroform as the solvent. There is a significant enhancement in optical, mechanical, photoacoustical and third-order non-linear properties have been attained due to the incorporation of dye in the host material. The unit cell parameters and crystallinity

Designing efficient and compact couplers is crucial in hybrid integration of plasmonic components with conventional silicon-on-insulator components. Taper-funnel structures are conventionally used to couple light from a silicon strip waveguide to a metal–dielectric–metal plasmonic waveguide. In this paper, we investigate the effect of different parameters of the metallic funnel and the vertically and

A method for precise adjustment of the power splitting ratio for integrated optical splitters fabricated on lithium niobate substrates is proposed. The method is based on a local refractive index change caused by the photorefractive effect under external illumination of certain areas of waveguide power splitters. A fiber optic probe was used for precise positioning of an external illumination spot

The beam quality of diode-pumped alkali lasers (DPALs) is of major concern in the studies of these lasers. We report on experimental studies and modeling of the beam propagation factor M2 in flowing-gas Cs DPALs with stable optical resonators and of its dependence on the resonator geometry. The measured values of M2 are in agreement with those calculated using the optical model of multi-transverse

In spray flame synthesis the processes of spray formation and evaporation of the single droplets greatly affect the morphology and size of particles formed. An in situ measurement of these parameters is thus essential for process control and development. In this work, wide-angle light scattering (WALS) is applied to measure droplet sizes in a spray flame. The scattering data of the spherical droplets

This paper presents experiment and analysis on variation of temperature sensitivity of resonant modes of a long period grating (LPG) with change in temperature. The theoretical analysis explains the corresponding experimental data on temperature sensitivity of LPGs written in house in Ge-B codoped and H2-loaded telecom fiber. The LPGs were first annealed for thermal stability. The average temperature

We introduced a theoretical model to preserve the quality and the efficiency of a picosecond second-harmonic generation (SHG) in a 30-mm-long LBO crystal which is surrounded by a thermal oven. It is proposed to arrange a temperature gradient throughout the crystal length for mitigating the undesirable consequences of dispersion and group velocity mismatch. To optimize the pulse shape, a distance parameter

It is a key procedure of measuring the diode laser wavelength in the wavelength modulation spectroscopy (WMS) technique since it determines the selection of specific modulation amplitude and frequency and thus the overall accuracy of the WMS technique. However, the wavelength modulation frequency of lasers is usually from tens of kHz to hundreds of kHz, which makes the traditional methods difficult

We present results on the lasing properties of the Bi-doped high-germania glass fibers thermally treated at different heating and cooling conditions. The absorption and luminescence spectra, the luminescence lifetime of bismuth-related active centers (BACs) formed in the Bi-doped fibers before and after treatment were measured. Analyzing the results, it was shown that the concentration of the BACs

Present-day laser-spectroscopy experiments increasingly rely on modern commercial devices to monitor, stabilize, and scan the wavelength of their probe laser. Recently, new techniques are capable of achieving unprecedented levels of precision on atomic and nuclear observables, pushing these devices to their performance limits. Considering the fact that these observables themselves are deduced from

Wavelength meters are widely used for frequency determinations and stabilization purposes since they cover a large wavelength range, provide a high read-out rate and have specified accuracies of up to \(10^{-8}\). More accurate optical frequency measurements can be achieved with frequency combs but only at the price of considerably higher costs and complexity. In the context of precise and accurate

We report a technologically novel microscopy system for bioimaging based on a 100 fs titanium:sapphire (Ti:Sa) laser pumped coherent continuum from a tailored, 9-cm long, all normal dispersion (ANDi) fiber, enabling concurrent image contrast with (a) spectral focusing coherent anti-Stokes Raman scattering (SF-CARS) (spanning 900–3200 cm−1) and (b) sum frequency generation (SFG). Both modalities were

We employed a hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) instrument to probe rotational temperatures of molecular hydrogen in the multiphase reaction zone of an aluminized ammonium perchlorate (AP) propellant flame. Significant concentrations of hydrogen, present in the plume due to the decomposition of the propellant binder material and subsequent reactions with

We have compared two kinds of dispersive mirrors (DMs) produced by magnetron sputtering and ion beam sputtering. One of them is a broadband DM which is known as double-angle DM, providing a group delay dispersion (GDD) of \(-40 \mathrm{{fs}}^2\) in the range of 550–1050 nm. The other one is a robust highly dispersive mirror, which provides a GDD of about \(-275 \mathrm{{fs}}^2\) at 800 nm and covers