Applied Optics

Figure 1 is corrected, and the assumptions used for calculating the optical path lengths are revised for the original paper, Appl. Opt.63, 1506 (2024)10.1364/AO.511270.

In this paper, a high-power all-solid-state ultrafast 2 µm mode-locked laser is investigated. The particularity of this laser is the simultaneous utilization of two Tm:YAP crystals in the same resonant cavity, independently pumped by two laser diodes. Using a 20% output coupler, pulses with output power as high as 1.83 W are achieved at a wavelength of 1938 nm with a pulse duration of 1.97 ps and a pulse repetition frequency of 100 MHz. To our knowledge, this mode-locked laser achieves the highest output power of any mode-locked Tm:YAP ultrafast laser reported to date...

We investigate the generation of an elliptical perfect optical vortex (EPOV) beam through the optical Fourier transformation of an elliptical Bessel-Gaussian beam and derive an analytical expression for its complex field amplitude. Our analysis includes the examination of the beam's propagation in free-space and the influence of topological charge on its transmission. The EPOV beam's propagation in free-space can be categorized into non-diffracting and diffracting stages. During the non-diffracting stage, the beam intensity and profile size are effectively preserved over a short transmission distance...

Due to the absorbing and scattering effects, underwater images are often degraded by low contrast, color cast, and haze, which have limited their further applications to underwater vision task. To address this issue, we propose a hybrid framework by adaptive color correction and dehazing for underwater image restoration. Specifically, according to the color attenuation principle, we first design an adaptive color compensation strategy to correct the color cast of the underwater image. In addition, based on an underwater image formation model, we develop a robust dehazing algorithm, in which a new scoring formula across three indicators (i...

Optical proximity correction (OPC) has become an indispensable step in integrated circuit manufacturing. It requires a huge amount of calculation to obtain a sufficiently accurate OPC model and implement pattern correction. In this paper, the authors proposed an edge-based OPC method built on a vector imaging model, where the analytical correlation between the cost function and movement of each edge segment is established by the chain rule. First, the mask pattern is segmented and downsampled to get the mask image in order to reduce the total data...

Aimed at the regional open-path detection of benzene ( C 6 H 6 ) in the atmosphere, a power-modulated integrated path differential absorption (PM-IPDA) lidar is introduced and demonstrated. Two tunable interband cascade lasers (ICLs) with about 3.2 µm wavelength are utilized to generate the required PM optical signal. These two operation central wavelengths (CWs) of the PM-IPDA lidar are, respectively, 3236.6 and 3187.1 nm, which can mitigate the influence of significant gases such as H 2 O , C H 4 , and HCl on the detection performance...

Monolayer molybdenum disulfide ( M o S 2 ) has a weak light-matter interaction due to ultrathin thickness, which limits its potential application in lasing action. In this study, we propose a hybrid structure consisting of a nanocavity and Au nanoparticles to enhance the photon emission efficiency of monolayer M o S 2 . Numerical simulations show that photoluminescence (PL) emission is significantly enhanced by introducing localized surface plasmon resonance (LSPR) to the proposed structure. Furthermore, an exciton energy band system is proposed to elucidate the physical mechanism of the PL process...

Accurate assessment of corneal curvatures using frequency domain optical coherence tomography (OCT) with galvanometer scanners remains challenging due to the well-known scan field distortion. This paper presents an algorithm and software for correcting the distortion using only two simple measurements in which a readily available standard sphere is positioned in different depths in front of the OCT scanner. This offers a highly accessible and easily reproducible method for the field distortion correction (FDC)...

The effect of a linear polarizer is conventionally well defined when viewed along the axis normal to its face. However, even for ideal linear polarizers, the non-normal viewing geometries attainable with wide-angle lenses require further considerations. A method to describe the polarization state of light passed through a linear polarizer and observed with an equidistant fisheye lens is described.

Different from the scalar optical field with spatially uniform polarization, the vector optical field exhibits inhomogeneous distribution of polarization on the cross section. Manipulating the variation of polarization in a single optical beam is important to acquire a flexible and controllable focused optical field. Previous studies mainly focused on the vector optical field with its polarization varying along a circular trajectory of the Poincaré sphere. Here, we demonstrate the tight focusing behaviors of the vector optical field with the polarization varying along complex curves of the Poincaré sphere, which is generated by the joint modulation of azimuthal phase and amplitude distributions of orthogonally polarized components...

A high-precision binocular camera calibration method is proposed to address the issues of poor calibration accuracy and large calibration errors in current practical applications. This method uses a triangular stereo sphere as the calibration object and employs steps, such as ellipse fitting, Cholesky decomposition, homography matrix solution, and nonlinear optimization, to compute the intrinsic and extrinsic parameters, distortion parameters, and relative pose of the binocular camera. Moreover, this method simplifies the correspondences between primitives, enabling simultaneous calibration of multiple viewpoint cameras...

In this paper, a highly sensitive pressure sensor based on fiber-optic Fabry-Perot interferometers (FPIs) and the Vernier effect (VE) is proposed and experimentally demonstrated. We employ a closed capillary-based F P I s for the sensing cavity, and an F P I r created through femtosecond laser refractive index modulation for the reference cavity, which remains impervious to pressure changes. Connecting these two FPIs in series produces a VE-based cascaded sensor with a clear spectral envelope. The femtosecond laser micromachining technique provides precise control over the length of F P I r and facilitates adjustments to the VE's amplification degree...

This paper addresses global warming concerns stemming from energy consumption, particularly in buildings, which contribute 40% to global energy use. Smart windows that reflect near-infrared radiation have emerged as a solution to reduce indoor temperatures. Chiral nematic liquid crystals (CLCs) play a crucial role in this technology. Numerous approaches have been explored for regulating indoor temperatures using liquid crystals. Despite achieving ideal transparency, rapid switching speeds, negligible power consumption, and user control over switching, reported samples often face challenges when attempting to revert from either the focal conic state or the transmitting state back to the initial reflecting state...

The degradation of imaging quality caused by environmental noise during Fourier single pixel imaging (FSPI) is a big problem. In this paper, we propose simple and efficient denoised single-pixel imaging schemes by using linear filters to reduce the impact. Two filters, such as an average filter and Gaussian filter, are employed, and their corresponding schemes are named SCH-A and SCH-G, respectively. The experimental and simulation results show that both schemes can effectively reduce the impact of environmental noise and have greater robustness in comparison with those using the deringing SPI and conventional SPI...

A novel scanning particle image velocimetry technique, to the best of our knowledge, is proposed to characterize flows in microfluidic applications. Three-dimensional information is acquired by oscillating the target sample over a fixed focal plane, allowing the reconstruction of particle trajectories with micrometer accuracy over an extended depth. This technology is suited for investigating acoustic flows with unprecedented precision in microfluidic applications. In this contribution, we describe the experimental setup and the data processing pipeline in detail; we study the technique's performance by reconstructing pressure-driven flow; and we report the three-dimensional trajectory of a 2 µm particle in an acoustic flow in a 525µ m ×375µ m microchannel with micrometric accuracy...

Optical-luminescence properties, including absorption spectra, photoluminescence excitation spectra, and changes in photoluminescence spectra after irradiation with γ -rays in the dose range of 1-3 Gy, were measured for novel L i B 3 O 5 : A g dosimeter glass. A clear dependence of the intensity of the photoluminescence (PL), with a maximum of approximately 300 nm, on the dose value when excited by light with λ e x c =220 n m was observed. The mechanism of PL in γ -irradiated L i B 3 O 5 : A g glass is proposed to be a consequence of radiation annihilation with the emission of relaxed exciton-like electronic excitations with the participation of impurity defects ( A g 0 ) in the glass structure...

When a binocular vision sensor (BVS) is installed in a narrow space, traditional calibration methods are limited as all targets should be placed in more than three different positions. To solve this problem, an on-site calibration method based on the phase-shift algorithm is proposed in our paper. Intrinsic parameters of these two cameras should be first calibrated offline. Series of phase-shift patterns are projected onto any one target with known three-dimensional information to determine the relationship between two cameras...

We have investigated the trapping force on low and high refractive index nano-particles using a highly focused Laguerre-Gaussian beam. An analytical expression for the gradient force has been derived in closed form. It was clearly found that the increase of the beam mode p causes a substantial increase in the number of trapping zones, which frequently increases the number of particles to be captured simultaneously. Also, the decrease of p values would increase the trap area, which consequently leads to simultaneous trapping of multiple particles in the same area...

High-quality single-photon sources are crucial for the development of simple quantum devices. Quantum communication stands at the forefront of cutting-edge technologies, promising unprecedented levels of security and efficiency. A cornerstone of this revolutionary field is the development of high-speed single-photon sources, which play a pivotal role in quantum key distribution and other quantum communication protocols. In this context, the concept of space multimode emerges as a promising avenue to propel the capabilities of single-photon sources to new heights...

Due to the presence of air turbulence in free-space optical (FSO) links, random fluctuations in wavefront phase and amplitude of the optical signal are reduced after it propagates through the air channel, which degrades the performance of free-space optical communication (FSOC) systems. Phase screen reflects the phase distortions resulting from air turbulence. Accordingly, accurate prediction with respect to phase screen is of significance for the FSOC. In this paper, we propose a phase screen prediction method based on the deep phase network (DPN)...