We present a chaotic lidar for underwater ranging and three-dimension (3D) imaging applications. The lidar transmitter based on a laser diode with free space optical feedback is designed to generate 520 nm wavelength wideband chaotic signal. This transmitter is used with a correlation-based lidar receiver to perform a ranging demonstration in clean water with a measured attenuation coefficient of 0

X-ray lasers based on transitions in highly-charged Ni-like ions generating in the “water window” wavelength range can be pumped by compact laboratory discharge sources. In this paper, we report the results of numerical simulations of the plasma dynamics and kinetics in an X-ray laser based on transitions in Ni-like xenon ions. The laser active medium is created by an extended low-inductive high-current

We investigate the operating modes of diode lasers in the external cavity scheme of spectral beam combining, using the virtual laser-diode array method. We determine the spectral range of the diode array and the watt–ampere characteristics of a single-diode laser for various wavelengths. We experimentally show that by varying the output coupler transmission with the wavelength, one can optimize the

We consider the implementation of the logical operation of disjunction of signals using accumulated stimulated echo holography. We study the processing of information embedded in the laser pulses of a pulse pair, with one of the pulses in the pair being an object and the other one having a wide frequency spectrum. We show that, taking the pulse spectra as narrow frequency regions within the inhomogeneously

We investigate the first-Stokes operation of YVO4 crystal driven by an acousto-optic Q-switched Nd:YAP laser with X(ZZ)X Raman configuration. The fundamental wavelength laser operation by Nd:YAP crystal was at 1080 nm corresponding to the first-Stokes wavelength at 1195 nm based on the Raman shift of 890 cm−1 in a-cut YVO4 crystal. Under an incident pump power of 8 W and a pulse repetition frequency

We investigate increase in the surface temperature of biased Si avalanche photodiodes (APDs) fabricated in an external capacitor circuit irradiated by a millisecond-pulse laser. The results obtained show that different external capacitance parameters have different effects on the temperature rise, the smaller the capacitance of external capacitor, the lower surface temperature increase in the APD.

In this work, we demonstrate a passively-Q-switched 1.33 μm Nd:Lu2YSc1.5Ga3.5O12 (Nd:LuYSGG) laser based on the Bi2Se3 topological insulator (TI) as a saturable absorber (SA). We obtain pulse widths as low as 146 ns at a pulse repetition rate of 349.5 kHz and a pulse energy of 1.03 μJ, which provides a peak power of 7.05 W. These results represent some of best yet published in terms of repetition rate

We design a high-sensitivity optical-fiber sensor for measurements of displacement and refractive index based on dual-coating-stripped loop-shaped single-mode fibers. For this, we produced two unrelated interference dips as a consequence of different radii of two loop-shaped fibers. Since loop-shaped optical fibers are assigned different tasks at the same time, the two dips present their own characteristics;

In this paper, we propose a three-dimensional (3D) integral image display method that uses the similarity of corresponding points in a series of axially recorded images. First, we calculate the corresponding points of a 3D object, in view of the proportional relationship of the distances of points in the elemental images collected, using axially distributed sensing (ADS). Next, we extract the depth

We study the emission spectrum and quantum-state fidelity for an atomic system interacting with radiation fields of quantum systems described by power-law potentials. We consider a set of manifold fields that are characterizable by their level-energy differences. They include triangular, infinite, and harmonic potentials as special cases. We present the time evolution of the spectrum and fidelity for

We derive the analytical expression of the probability density of orbital angular momentum modes for elegant and standard Laguerre–Gaussian beams in turbulence. The results show that we can increase the initial topological charge of the beams to reduce the detrimental mode crosstalk induced by the turbulence. We also discuss the influence of the beam parameters on the probability of signal and the

We study the employment of an adopted optics system for the reduction of thermal blooming effects by the phase correction of a 1.064 μm laser. The energy concentration of the beam spot in the farfield substantially increases if the adaptive optics system is performed in a closed loop. The phase compensation of the adapted optics system is effective for a Bradley–Hermann distortion number of less than

We present quantum formula for extropy based on the Husimi Q-function and the atomic Husimi Q-function. The quantum extropy is used to detect the entanglement or nonlocal correlations of the system consisted of a single qubit and the radiation field. We provide explicit forms of the binomial and even binomial distributions. We compare the temporal behavior of quantum extropy within the atomic and field

Based on the finite-difference-time-domain method and the plane-wave method, we study the imaging performance of two-dimensional hexagonal-structure photonic-crystal flat panel lens. First, the plane wave expansion method is used to verify that the structure has a negative refraction effect. The equivalent refractive index is – 1 when the normalized frequency is 0.251. The finite-difference-timedomain

The passively Q-switched (PQS) operation of a Tm:YAP laser was experimentally demonstrated with an MoSe2 saturable absorber (SA). In the PQS mode, an average output power of 1.084/1.744 W with a pulse width of 686.0/1222 ns at 196.5/177.7 kHz was acquired from Tm:YAP laser under an output couple (OC) with transmittances T of 2%/5%, corresponding to an optical–optical conversion efficiency and an output

We present a passively Q-switched Ho:Sc2SiO5 microchip laser with a molybdenum disulfide saturable absorber for the first time. The molybdenum disulfide materials are fabricated on the end surface of a microchip Ho:SSO crystal. The physical length of the laser cavity is only 3 mm. Three output couplers with different transmissions are utilized to test the passively Q-switched laser performance. The

We report a stable high-power all-solid-state Q-switched laser operating at 294.6 nm with a pulse width of 24 ns and a repetition rate of 20 kHz produced by intracavity sum-frequency generation and external frequency doubling in LiB3O5 and β-BaB2O4 crystals, respectively. Upon synchronizing the fundamental lasers, the maximum output power at 589 nm is 1.2 W, which is frequency doubled to produce up

We design a competent gain-flattened and noise figure in L-band hybrid optical amplifier using a hybrid configuration with a Raman amplifier (Raman) and quantum-dot vertical-cavity semiconductor (QDVC-SOA) for a 400×20 Gbps super-dense wavelength division multiplexing system (SD-WDM) at channel spacing 100 GHz. The proposed hybrid optical amplifier (HOA) shows that it can be constituted into an optical

We demonstrate a 355 nm ultraviolet nanosecond laser produced by the type I phase-matched frequency doubling in a K3B6O10Br (KBOB) nonlinear optical crystal. The use of 5022 μJ, 710 nm pump pulses at 10 Hz repetition rate produces 4.273 ns, 355 nm, 717 μJ pulses that corresponds to a frequency doubling conversion efficiency of 14.3%. The energy instability of the frequency-doubled pulse train measured

For the first time, we present a passively Q-switched 1060 nm Nd:GSAG laser using a two-dimensional molybdenum disulfide (MoS2) nanosheet as saturable absorber. We investigate in detail the output characteristics of this laser such as average output power, pulse repetition rate, pulse width, pulse energy, and pulse peak power.

A polycrystalline diamond film is grown on a 2 inch Si substrate using a microwave-plasma chemicalvapor-deposition technique. The high quality of the diamond films is confirmed by Raman spectra. A multiple-step procedure is used for local etching of the substrate to form the pattern of an array of 50 diamond membranes with the diameter in a range from 150 to 300 μm. The morphology of the membranes

In this paper, we give an overview of nonclassical effects, such as squeezing and sub-Poissonian states, of an optical field in coherent anti-Stokes Raman scattering and coherent anti-Stokes hyper-Raman scattering under the short time scale. We establish the coupled Heisenberg equations of motion of quadrature operators in terms of real and imaginary parts. We investigate the photon statistics of the

For the first time, we obtained the photoreflectance spectra in single-layer samples of porous silicon with 13 μm thick in the 550–1000 nm spectral region. To describe the observed reflection and photoreflectance spectra, we use a theory of multiple-beam interference, taking into account the strong absorption of Si in this spectral region. We show that, under the action of a laser radiation with a

The electron density distribution and average electron temperature distribution in reactive ion etching (RIE) chamber are of great significance for the ionization and excitation reaction rate. The uniformity of radial distributions of the electron density and average electron temperature in the discharge chamber greatly affects the uniformity of the etching, especially the plasma etching of large area

Two superconducting (SC) qubits interacting with a radiation field in the coherent state (CS) in the presence of Stark shift are investigated. The density matrix is expressed in terms of the wave function to describe the proposed system. Physical properties, such as the geometric phase, linear entropy, and negativity are used to describe the behavior of the system. The effects of the Stark shift and

We investigate dynamics of quantum entanglement (QE) and quantum Fisher information (QFI) of a system of two four-level atoms moving in the thermal environment. The time evolution of the state vector of the whole quantum system interacting with the thermal field is investigated numerically in the presence of intrinsic decoherence (ID). We see that ID and the thermal environment play a prominent role

To date, it is a common knowledge that there exists two kinds of turbulence in Earth’s aerosphere, the Kolmogorov turbulence and the non-Kolmogorov turbulence, which has been confirmed by both increasing experimental evidences and some results of theoretical investigations. Therefore, it is necessary to further develop theory of optical wave propagation through the atmospheric turbulence, namely, to

We consider coherent dynamics of cold atoms in a square optical lattice without interference between counter-propagating laser beams. The dynamics is treated within the framework of semi-classical approximation, taking into account a coupling between the atom internal and external degrees of freedom. The corresponding set of equations of motion has been found before to be regular or chaotic in dependence

We investigate the multiphoton coherence effects on two weak probe-beam transitions in a five-level double-inverted Y system, where the two probe transitions are also affected by phase-dependent χ(3) processes occurring via Λ and Ξ channels. This system provides two channels to create each two-photon coherence and three-photon coherence. We show that quantum interference induced by the closed loop

We carry out the experimental study on Brillouin erbium fiber laser in two different structure configurations. In the first configuration, Brillouin pump laser directly stimulates the Brillouin scattering light, whilst in the second it gets pre-amplification before stimulating the Brillouin scattering light in silica optical fiber. Employing distributed-feedback fiber laser as the Brillouin pump laser

We propose and experimentally demonstrate a novel and simple approach to implementing optical single-sideband (OSSB) modulation with tunable optical carrier-to-sideband ratio (OCSR) based on a dual-polarization Mach–Zehnder modulator (DPol-MZM) and a polarizer (Pol). In this scheme, the light wave is modulated by radio frequency (RF) signal with SSB modulation in the upper arm of the DPol MZM, while

We study theoretically and experimentally superradiant dynamics in multiple-section GaAs/AlGaAs laser structures. We develop a model based on the one-dimensional Maxwell curl equations without making use of the slowly-varying envelope approximation and demonstrate that strong transient periodic modulation of both e – h density and refractive index drastically affect the dynamics of emission generation

Despite their recognized merits in terms of discrimination, compactness, and robustness, chord-length shape features have not received a great deal of attention in the literature on license plate recognition. In this paper, we present an innovative k nearest neighbors (kNN) approach for license plate detection and recognition, where a new low-dimensional descriptor that incorporates shape information

We investigate the possibility of improving the reconstruction accuracy of electron density distributions ne(r) for plasma objects with a complex structure by processing the results of combined interferometry and schlieren photography. We carried out the numerical simulations for a spark channel with a micrometer-sized diameter developing in atmospheric air. We show that the data obtained from the

Undoped and aluminum-doped ZnO (AZO) thin films were prepared by the sol–gel process. Single thin layers were synthesized at room temperature by spin coating on glass and silicon substrates. The gel was laser irradiated (530 nm, 10 W) during the spinning process. We used Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) to characterize the chemical bonding configuration

The eye is the most important sensory organ of the human body, and the cornea and anterior chamber are very important components In surgeries like vision correction, it is necessary to know the accurate corneal thickness and anterior chamber depth of human eyes. Their accurate measurement cannot only provide a reference for doctors, but also provide a strong guarantee of surgical results. In order

As a bridge between crystal and fiber, the single crystal fiber (SCF) can combine the advantages of the two materials and show great potential in high-power lasers. In this paper, we select a Nd:YAG SCF as the gain medium in a diode-end-pumped linear cavity. The Nd:YAG SCF with the dimensions of ∅ = 1 mm × 50 mm was manufactured using the micro-pulling-down technique. At an incident pump power of 153

In this paper, within the framework of classical electrodynamics, we rederive in a simple way the formula for the cross section of light scattering by a moving particle. The results are of interest for the community of researchers working on laser-electron X-ray generators.

The three-dimensional microsolid can be fabricated by scanning point-by-point inside the polymer material according to the predetermined trajectory in femtosecond-laser two-photon direct writing mode. In the process of machining, the shape and intensity distribution of focus spot are changed by some processing parameters, which affect the processing accuracy and surface quality. Based on Fresnel diffraction

We demonstrate a synchronously self-Q-switched and self-mode-locked output pulse fiber laser based on a linear compound resonator and an LD cladding-pumped Yb-doped double-clad fiber. A maximum average output power of 332.1 mW is achieved. We observe that the maximum pulse envelope width is 8 μs, and the pulse energy is 3.83 μJ for the self-Q-switched pulse envelope. At the same time, the achieved

Electric quadrupole interactions are normally weak but are shown capable of being exploited once the neutral atom interacts at near resonance. The physical model used here is based on evanescent Hermite–Gaussian light in a vacuum being total-internally reflected at the planar surface of a dielectric. The resulting optical quadrupole potential distribution is restricted to a subwavelength region near

Synthetic aperture imaging systems can be applied to equivalently get high-resolution images of traditional monolithic primary mirror systems with less weight and costs. Spatial modulation diversity (SMD), a newly developed post-processing technology applicable for such synthetic aperture systems, is very sensitive to Gaussian noise, which greatly limits its further application. In this paper, we propose

In this communication, we consider a pair of entangled quantum systems, each described by the su(1) Lie algebra, interacting with two two-level atoms. We discuss in detail the influence of the detuning terms on the system and derive from the Heisenberg equations of motion the expressions of various operators corresponding to the dynamics. Solving the associated Schrödinger equation, we obtain the general

In this paper, we demonstrate for the first time a doubly Q-switched pulsed laser, using a novel Nd:Gd0.69Y0.3NbO4 mixed crystal and acousto-optical (AO) Q-switch and Cr4+:YAG saturable absorber. Compared to purely AO Q-switched lasers, the simultaneous use of AO Q-switches and Cr4+:YAG saturable absorbers provides the generation of a shorter pulse. We investigated in detail the output characteristics

We demonstrate a novel continuous-wave 2.1 μm Ho :GTO laser pumped by a laser diode. Employing a pump recycling scheme and 30% output transmittance, we obtain an output power of 4.76 W and a single oscillating peak of 2068.4 nm with a slope efficiency of 55.3% with respect to the absorbed pump power. In addition, the M2 factor of the Ho :GTO laser is reckoned to be approximately 1.3 at the maximum

By calculating the heterojunction band alignment of GeSn/SiGeSn, a Ge0.9Sn0.1/Si0.14Ge0.71Sn0.15 multi-quantum-well laser was designed, where three Ge0.9Sn0.1 layers act as wells separated by three Si0.14Ge0.71Sn0.15 layers as barriers. The maximum TE gain reaches 7000 cm−1 at 0.5 eV, and the maximum TM gain reaches 5500 cm−1 at 0.52 eV. The modal gain of the Ge0.9Sn0.1/Si0.14Ge0.71Sn0.15 multi-quantum-well

We report high-performance broad-area eight-layer InAs/GaAs quantum-dot lasers (QDLs) emitting at 1.3 μm in the pulse and continuous-wave (CW) operations. Operational characteristics of the fabricated QDLs, including the emission wavelength, output power, threshold-current density, differential quantum efficiency, and characteristic temperature, are investigated at different temperatures. For as-cleaved

Abstract In the constant-intensity approximation, we analyze the nonlinear quasiphase-matched frequency doubling and tripling in the case of a backward second-harmonic wave. The third harmonic conversion efficiency for different orders of the quasiphase matching is analytically calculated. We show that there exists an optimum value of the ratio of nonlinear coefficients (β3/β2)opt and find that the

In this paper, we investigate the emission spectrum of a two-level atomic system interacting with an optical radiation field based on photon-added coherent states of a pseudo-harmonic oscillator (PACSPHO). Also, the purity of the optical field initially prepared in the PACS-PHO is studied through the evolution of the field entropy. We examine the influence of the intensity-dependent field and the photon-transition

We construct a new class of photon-added squeezed states using a single-mode bosonic realization of the su(1) Lie algebra and explore their squeezing properties as a function of the added-photon number. We observe that their squeezing property increases with increase in the number of added photons. In addition, we discuss some basic properties, such as nonorthogonality and resolution of identity. Such

Abstract The beaconless acquisition pointing and tracking (APT) system uses signal light to act as beacon. But the signal light’s divergence angle is so small that it is difficult to capture. In this work, aiming at the different requirements of divergence angle for a free-space optical-communication (FSO) system in a different working phase, we use a stepper motor for automatic focusing control in