Quasi-single-photon sources are attracting a lot of interest in many fields at present; however, the knowledge is very poor about their performance. In this Letter, by using the standard Hanbury-Brown-Twiss measurement method, we

The nonideal semi-Gaussian beam generated in our work has a certain ascent border width. Due to its asymmetry, the propagation properties of a nonideal semi-Gaussian laser beam in nonlinear materials have some unique characters. I

In our work, a high-quality broadband femtosecond optical vortex is obtained by use of a continuous spiral phase plate (SPP) to modulate an ultrashort femtosecond (fs) laser with a broadband spectrum. The experimental results demo

A low-coherence fiber-optic dynamic light scattering (FODLS) technique is utilized to measure the effective viscosity of colloidal suspensions over a range of temperatures and volume fractions. Based on the single scattering theor

A new filter spectrometer for the simultaneous measurement of plasma ion temperature and rotation velocity on the experimental advanced superconducting tokamak is proposed. The Doppler broadening and Doppler shift of the plasma sp

Null lenses are always used to test large convex aspheric mirrors. For large convex aspheric mirrors with large deviate wavefronts from the aspheric wavefront to its best sphere wavefront, a traditional null lens composed of a fla

In order to solve the problem of direction discrimination and low-speed measurement for a spatial filtering velocimeter, a method of frequency shifting is put forward. The filtering device is constructed by a CMOS linear image sen

We set up a pulsed beam steering system with a simple feedback control method. The system applies an integration circuit to process a 2 μs short pulsed beam with a repetition rate of 25 Hz, and employs an iteration method to corre

Some problems and confusions related to matrix analysis for Gaussian beam reflection are clarified. We can choose right-handed coordinates before and after mirror reflection which is called the traditional coordinate system in thi

We report a Q-switched self-Raman third-Stokes laser at a wavelength of 1487 nm, with a YVO4/Nd:YVO4/YVO4 composite crystal and a high-power fiber-coupled diode laser array at 808 nm. The maximal average output power at 1487 nm is

An amplified and narrow-linewidth distributed feedback fiber laser in a master oscillator power amplifier (MOPA) configuration is presented. It consists of a distributed feedback fiber laser as the seed laser and an MOPA structure

For polarization switching (PS) and nonlinear dynamic behaviors (NDBs) of an optically injected laser system composed of a master vertical-cavity surface-emitting laser (VCSEL) and a slave VCSEL, we put forward a novel manipulatio

We investigate propagation of a finite energy Airy beam in a gradient-index fiber analytically and numerically, and find that the beam not only repeats its intensity features, but also has the phenomenon of self-focusing and self-

A Collins formula method with a scaling factor between the target and source plane is proposed for laser propagation in optical system design, which can be used to evaluate laser optical system performance and tolerance analysis.

A new shorter T-shaped thermo-stable telescopic resonator is demonstrated in this Letter. By means of thick lens model, a longer 1064-nm telescope linear cavity is designed and simulated first by analyzing the influence of the dis

To obtain a laser output with a high-quality beam and a square, super-Gaussian, flat-top distribution, a high-energy laser needs to conduct spatial reshaping of the geometric outline of an injected Gaussian laser pulse and the non

We report on the frequency stabilization of Er-doped fiber lasers against rotovibrational absorption lines of molecular H13C14N at 1550 nm by means of the frequency modulation spectroscopy technique. The laser frequency is locked

We propose a novel pulse amplification model to obtain the effective thermal equilibrium time (τETE) for Yb:YAG crystal, where τETE has impacts on the gain recovery and energy extraction. A test amplifier is set up to measure the

The temporal evolution of Nd:YAG laser-produced Sn plasma in atmospheric pressures from 5 to 104 Pa is investigated. The results show that the extreme ultraviolet radiation exists only at the beginning of the expansion process for

We theoretically investigate the dynamics of thermalization in Au-Ti double-layered film irradiated by a femtosecond laser pulse. A nonequilibrium thermal relaxation model is proposed to study the energy deposition and transport p

We report on a spectral beam combination of five narrow-linewidth fiber amplifiers. The five-channel output beams are combined in both the near and far field using a polarization-independent diffraction grating that mainly preserv

In this Letter, microwave generation based on frequency multiplication with fiber ring loop modulation and microwave photonic filters is proposed and experimentally demonstrated. High-order microwave harmonics can be generated and

We demonstrate a multiwavelength Tm-doped fiber laser employing polarization-maintaining undoped fiber (PMF) based on nonlinear polarization rotation. The PMF and a polarization-sensitive isolator between two polarization controll

For a long communication distance, the divergence angle of laser transmission by a space laser communication system must be sufficiently narrow to solve the energy problem. However, it needs to be magnified during the ground test

A new distributed temperature sensor based on stimulate Brillouin scattering (SBS) is designed by filling alcohol in a photonic crystal fiber (PCF). Since the refractive index of alcohol varies with temperature, which results in t

In this Letter, we propose a scheme that integrates a diversity-combining technique with asymmetrical clipping optical orthogonal frequency-division multiplexing (ACO-OFDM) based on a discreet Hartley transform (DHT). Simulations

We present a phase difference range system with about 1.5 GHz of modulation frequencies. To reduce the phase difference drift, the high-frequency signals are synthesized by digital fractional phase-locked loops, and a differential

The goal of this work is to evaluate the compositional and morphological changes of human dentin after erbium, chromium:yttrium–scandium–gallium–garnet (Er,Cr:YSGG) laser irradiation by Raman spectroscopy. The dentin surface of hu

We investigate the one/two-photon fluorescence of two synthesized phenoxy-phthalocyanines (Pc1 and Pc2) using the mild reaction coordination method and the nonlinear optical properties of Pc1 and Pc2 in solution are investigated u

To investigate the relationship between indium content and optical properties during epitaxial growth of an InGaAs/GaAs single quantum well (SQW), simulation and experiments are demonstrated. The epitaxial growth is demonstrated w

We investigate the 120 keV hydrogen ion-implanted LiTaO3 samples. To observe the implantation-induced crystal structure and composition changes we use Raman scattering, infrared spectroscopy, and cross-section transmission electro

The defect evolution is investigated for high-reflective coatings under multiple irradiations with an improved statistical model. The fatigue effect is observed with an increase in the shot numbers, but the fatigue process will no

Second-harmonic generation (SHG) from aperiodic optical superlattices in the regime of pump depletion is investigated, when the influence of typical fabrication errors, which can be introduced by the random fluctuation of the thic

The theoretical study of the film thickness distribution deposited on a parabolic substrate by vacuum evaporation is reported. It is derived that the value of n/h and L/h strongly affect the coating thickness distribution (where h

The slope of the root-mean square (RMS) can be applied to evaluate mid-spatial frequency mirror surface errors for larger-aperture mirrors. In this paper, the slope RMS is analyzed from three different perspectives. First, the rel

This Letter reports a series of experiments on examining the removal function of a 400 mm magnetorheological finishing (MRF) polishing wheel which is aimed at large optical component fabrication. This MRF equipment is assembled on

A new method developed for wavefront error (WFE) testing of an assembled space telescope is described in this Letter. The main idea of this method is to image a small bright target on the focal plane array assembly by the space te

We use inductively coupled plasma chemical etching technology (PCET) operating at atmospheric pressure to fabricate an optical mirror whose materials are fused silica, reaction bonded SiC, sintered SiC, and Si for the first time,

In this Letter, we present a method to measure the eccentricity of an off-axis asphere using a laser tracker during optical null testing. We first adjust the optical path of the null testing, and then probe some necessary referenc

Off-axis systems built by freeform optics are greatly demanded in next-generation space telescopes/cameras, for obtaining a long focal length and wide field of view. The profile accuracy of the mirror surface is the most critical

A derivative method for phase retrieval in two-step phase-shifting interferometry (PSI) with a blind phase shift is proposed in this Letter. By numerically calculating the first-order and second-order derivatives of two PSI images

Definitions of mode-field half-width and divergence half-angle according to different kinds of methods are analyzed in this work. Numerical results of these definitions are given for the fundamental mode and suggest that some of t

The advantages of manufacturing a space aspheric mirror of SiC material are analyzed, and the key methods and technology of fabricating and measuring SiC aspheric surfaces are introduced and researched. The off-axis SiC aspheric m

We describe the design and capabilities of the x-ray excited optical luminescence (XEOL) technique at the scanning transmission x-ray microscopy beamline (BL08U1A) of the Shanghai Synchrotron Radiation Facility. The detection syst