After the discussion on thermal polarization theory from part 1 of this review, we now review practical methods for experimentally measuring infrared polarization properties. Starting with a model for thermal emission from inhomogeneous media, we discuss the complexities of paints and how to determine the ideal thickness of paints used for blackbody simulators. Another commonly used inhomogeneous material is anodized aluminum, and we provide an extensive discussion of its fascinating structure and its optical properties in the thermal infrared. Theoretical analysis and experimental measurements show how the peculiar properties of alumina in the longwave infrared region combine to create a material that has a surprisingly high emissivity, for optically smooth sapphire and highly inhomogeneous anodize-coated aluminum. To illustrate features of thermal polarization theory given in part 1 of this review, we also present a series of infrared polarization images, and demonstrate the use of a convenient reference source for thermal polarization testing.

Guest editors Matthew T. Posner, Anne-Sophie Poulin-Girard, and G. Groot Gregory introduce the Special Section on Education and Training in Quantum Sciences and Technologies.

The Networked Quantum Information Technologies (NQIT) hub was one of the quantum hubs of the first round of the United Kingdom’s flagship scheme, bringing together academia, industry, and government. The Optical Engineering and Quantum Photonics Group at the University of Southampton’s Optoelectronics Research Centre has developed an interactive demonstrator of a key device within NQIT to bring quantum photonics technologies to a wider audience. The system was exhibited at the 2017 UK Quantum Showcase in London to an audience of industry and government. It also featured as part of the Quantum City stand at the 2018 Cheltenham Science Festival, one of the United Kingdom’s leading annual science events.

Quantum-based technologies have been instrumental in the development of a whole range of devices that are used these days (such as lasers, transistors, LiDAR, GPS, MRI, and many more). These technologies that emanated from the Quantum 1.0 Revolution have become ubiquitous in modern civilization over the past 50 years. The product commercialization and mass production were enabled by scientists, researchers, engineers, and most importantly, by the skilled technological workforce. This workforce played a critical support role in transforming inventions into high-volume, marketable products. We are currently at the heart of the Second Quantum Revolution, which is fueled by the research in quantum computing, quantum communication, quantum cryptography, and quantum sensing. The scientific progress that is currently taking place in these areas is going to fundamentally change the way we sense the world around us, approach our security, and process critical information. Governments and private entities across the world have recognized the strategic importance of quantum research-enabled technologies and have invested a significant amount of money to support graduate programs and research institutions where scientists, engineers, and other professionals are earning advanced degrees and immediately being engaged in active Quantum 2.0 research. To the best of our knowledge, and despite considerable investment in quantum research, no active efforts or programs exist that would train a quantum technological workforce at the technician level to support Quantum 2.0. The quantum industry, on the other side, has clearly identified the need for highly skilled quantum technicians that are able to support the commercialization of the new products and inventions. The lack of a trained quantum technician workforce is a major shortcoming that may have a profound negative impact on the long-term prospects and sustainability of the emerging quantum industry. The EdQuantum project, funded through the National Science Foundation (NSF) Advanced Technological Education (ATE) program, is an effort to close this shortcoming and propose a well-defined curriculum through which the incumbent photonic and laser technicians in the United States will be upskilled with the new skills and competencies from quantum research-enabled technologies. This paper presents the results of the first phase of the EdQuantum project—the quantum industry survey. Over the last few months, we sought input from the quantum industry as to what skills and competencies should a future quantum technician possess to support its emerging needs. The results collected during the survey are presented in this paper along with their impact on the proposed educational curriculum. This paper also elaborates on the alignment of the proposed curriculum with a few ongoing initiatives in the skilled technical workforce education (such as NSB Vision 2030, Convergence Accelerators Initiative, and Skilled Technical Workforce Initiative).

We present a user-friendly software for photonic analog quantum computing with a graphical user interface (GUI) that allows for convenient operation without requiring programming skills. Hamiltonians can be flexibly set by either importing the waveguide position files or manually plotting the configuration on the interactive board of the GUI. Our software provides a powerful approach to theoretical studies of two-dimensional quantum walks, quantum stochastic walks, multiparticle quantum walks, and boson sampling, which may all be feasibly implemented in the physical experimental system on photonic chips, and it will inspire a rich diversity of applications for photonic quantum computing and quantum simulation. We have improved algorithms to ensure the efficiency of permanent calculation and provided case studies on educational uses, which bring users easier access to the studies of photonic quantum simulation.

To engage college students with electromagnetic waves and quantum physics, connecting course content to their everyday lives and to promote “photonics awareness,” a 12-week group research project on a photonics-based Nobel prize was developed. The project uses an inquiry-based approach and is designed as a five-part activity, each with a specific scaffold helping guide students regulate their inquiry.

Rapid advances in quantum technology have exacerbated the shortage of a diverse, inclusive, and sustainable quantum workforce. National governments and industries are developing strategies for education, training, and workforce development to accelerate the commercialization of quantum technologies. We report the existing state of the quantum workforce as well as several learning pathways to nurture the talent pipeline between academia and industry. We provide a comprehensive guide to various educational initiatives accessible throughout the world, such as online courses, conferences, seminars, games, and community-focused networks, that facilitate quantum training and upskill the talent needed to develop a better quantum future.

We describe the design and realization of an interactive art exhibition on the theme of quantum physics. The exhibition comprises five installations, developed by a group of scientists and artists based in Zurich, Switzerland, at the time of development. The installations are interactive art pieces, and their goals are to raise awareness of the general public and policy and government officials toward quantum computing, to provoke viewers’ questions on how quantum phenomena work, and to inspire them to learn more about quantum physics. Scientific experts in the field acted as ambassadors during the exhibition, delivering a guided experience to the visitors. The exhibition was showcased during the World Economic Forum held in Davos, Switzerland, in January 2020 as part of the Eidgenössische Technische Hochschule Zürich Pavillion.

Virtual Lab by Quantum Flytrap is a no-code online laboratory of an optical table, presenting quantum phenomena interactively and intuitively. It supports a real-time simulation of up to three entangled photons. Users can place typical optical elements (such as beam splitters, polarizers, Faraday rotators, and detectors) with a drag-and-drop graphical interface. Virtual Lab operates in two modes. The sandbox mode allows users to compose arbitrary setups. Quantum Game serves as an introduction to Virtual Lab features, approachable for users with no prior exposure to quantum mechanics. We introduce visual representation of entangled states and entanglement measures. It includes interactive visualizations of the ket notation and a heatmap-like visualization of quantum operators. These quantum visualizations can be applied to any discrete quantum system, including quantum circuits with qubits and spin chains. These tools are available as open-source TypeScript packages – Quantum Tensors and BraKetVue. Virtual Lab makes it possible to explore the nature of quantum physics (state evolution, entanglement, and measurement), to simulate quantum computing (e.g., the Deutsch-Jozsa algorithm), to use quantum cryptography (e.g., the Ekert protocol), to explore counterintuitive quantum phenomena (e.g., quantum teleportation and the Bell inequality violation), and to recreate historical experiments (e.g., the Michelson–Morley interferometer).

We provide an extensive overview of a wide range of quantum games and interactive tools that have been employed by the quantum community in recent years. We present selected tools as described by their developers, including “Hello Quantum, Hello Qiskit, Particle in a Box, Psi and Delta, QPlayLearn, Virtual Lab by Quantum Flytrap, Quantum Odyssey, ScienceAtHome, and the Virtual Quantum Optics Laboratory.” In addition, we present events for quantum game development: hackathons, game jams, and semester projects. Furthermore, we discuss the Quantum Technologies Education for Everyone (QUTE4E) pilot project, which illustrates an effective integration of these interactive tools with quantum outreach and education activities. Finally, we aim at providing guidelines for incorporating quantum games and interactive tools in pedagogic materials to make quantum technologies more accessible for a wider population.

We describe a coherent undergraduate educational program in nanoscience and nanoengineering at the University of Rochester (UR) based on the Institute of Optics and Integrated Nanosystems Center resources. This project has three main outcomes: (1) developing a curriculum and offering the Certificate in Nanoscience and Nanoengineering (CNSNE); (2) creating an exemplary model of collaboration in nanotechnology between a university with state-of-the-art, expensive experimental facilities and a nearby two-year community college (CC) with the participation of the local Monroe Community College (MCC); and (3) developing universally accessible “hands-on” experiments (mini-labs) on nanophotonics/quantum nanophotonics, learning materials, and pedagogical methods to be introduced in some Institute of Optics classes from freshman to senior levels. The inexpensive mini-labs described herein can be adopted in small colleges. An important outcome of this project is that ∼50  %   of the 41 awardees of the CNSNE (by May 2021) after graduation continued their career in the field of nanoscience and nanoengineering. For the CNSNE program, UR students must take three courses: Nanometrology Laboratory (a new course specifically created for this program) and two other selective courses. Students should also conduct a one-semester research or design project in the fields of nanoscience and nanoengineering. A total of 52 MCC students (including non-science, technology, engineering, and mathematics major students) participated in two labs at the UR on atomic force microscopy and photolithography in a clean room. Our teaching methodology, the progress of students’ learning outcomes, and the investigation of students’ attitudes and self-efficacy toward selecting their careers in nanoscience/nanotechnology are also discussed and analyzed. Discussions on the challenges in teaching advanced lab classes during the pandemic, our solutions for preserving the CNSNE program, and lessons learned are also included.

The quantum optics/quantum information and nano-optics educational laboratory facility (QNOL) at the University of Rochester (UR) is located within three rooms of the Institute of Optics with a total area of 587 ft². It has been used for teaching a 4-credit-hour QNOL class annually for 15 years. Four teaching labs were prepared on the generation and characterization of entangled and single (antibunched) photons demonstrating the laws of quantum mechanics: (1) entanglement and Bell’s inequalities, (2) single-photon interference (Young’s double slit experiment and Mach–Zehnder interferometer), (3) single-photon source I: confocal fluorescence microscopy of single nanoemitters, and (4) single-photon source II: a Hanbury Brown and Twiss setup, fluorescence antibunching. Further, based on QNOL, 1.5 to 3 h sturdy quantum “mini-labs” were developed and introduced into the required classes such that all optics students at the UR had experience with quantum labs. Monroe Community College (MCC) students participated in two mini-labs at the UR. Since 2006 to spring 2022, a total of ~850 students have utilized the labs for lab report submission (including 144 MCC students) and more than 250 students have used them for lab demonstrations. In addition, UR freshman research projects have become a very important educational activity in this facility. All developed materials and students’ reports are available at http://www.optics.rochester.edu/workgroups/lukishova/QuantumOpticsLab/. We present a description of sturdy, universally accessible experiments that can be introduced into either a separate advanced class or into classes with a large number of students. Assessment methods, evaluation of students’ knowledge, and their attitude toward their career in quantum information are discussed.

When cells are observed with a microscope, the phase information for the sample is usually obtained from the acquired intensity images using the transport of intensity equation (TIE). However, to solve the TIE, it is necessary to obtain an in-focus image. The accuracy and speed of focus positioning affect the accuracy and time of phase retrieval. We propose a fast phase retrieval method based on the TIE and the threshold duty ratio. We first perform pixel reduction on a series of acquired intensity images, and these images are segmented using the optimal threshold to calculate the threshold duty ratios. The original image corresponding to the minimum threshold duty ratio is the optimal focus image. Finally, the optimal in-focus image and related defocused images are used to solve for the phase of the sample using the TIE under the boundary conditions. The correlation coefficient for the results of the simulation experiment reached 0.9317. In a microlens array experiment, the relative error between the results from our algorithm and the actual value was only 7.1%, thus, proving the correctness and effectiveness of the proposed method.

We propose a panoramic vibration measurement system for the inner cylindrical surface of an object based on amplitude fluctuation electronic speckle pattern interferometry and developed according to the Michelson interference configuration. A conical mirror, aligned to the axis of the inner cylindrical surface, is illuminated to transform a single camera view into a panoramic view. After transposing the observation coordinate system, a complete inner 360-deg vibration pattern can be reconstructed. The principle of transformation from a Cartesian-coordinate system to a cylindrical-coordinate system is introduced in detail. The panoramic vibration of the inner circular tube is determined, and the first six modes are analyzed. The comparison and error analysis of the proposed system with the ANSYS simulation results prove the accuracy and feasibility of the system.

Super-resolution optical fluctuation imaging (SOFI) is an extensively used super-resolution (SR) imaging technique. The sample condition and imaging system are simpler than most SR systems, and the cusp-artifacts limit the resolution of high-order SOFI. To improve the resolution of SOFI, an alternative method is to improve the reconstruction algorithm. Here, compressive sensing (CS) is used in SOFI to improve its resolution. The detailed CS reconstruction algorithm is chosen as multiple measurement vector model sparse Bayesian learning (MSBL). We demonstrate that MSBL can achieve higher than threefold resolution improvement in simulation under certain conditions. The SOFI experiment analysis demonstrates that MSBL can improve the resolution about 2.5-fold compared with the diffraction limit. All results prove that MSBL has a higher resolving ability compared with other algorithms. Our results prove that CS is a broad applicability tool for most of the existing SR microscopy techniques and can be applied in 3D and live-cell SR fluorescence microscopy imaging in the future.

As memory device packaging moves toward die stacking technology with thin chips of high density, wafer dicing has recently become a key factor in semiconductor yield. Stealth dicing technology, which produces laser irradiation inside the wafer to form a modified layer within the wafer without any damage to the surface, is an alternative and advanced dicing process that is in line with the future trend of thin wafers. The existing stealth dicing process that utilizes an ultrashort pulse laser is expensive. In this study, we proposed a low-cost method for wafer stealth dicing using quasi-continuous wave (QCW) lasers. We redesigned the focusing lens of a QCW metal-cutting laser machine to form a cutting head with a high numerical aperture (NA) that is suitable for wafer stealth dicing. An optothermal model used to simulate the dicing process and calculate the temperature was implemented numerically based on the Crank–Nicolson algorithm and the successive over-relaxation method. Both the simulation and experimental results demonstrate that a QCW laser machine with a high-NA focus lens is ideal for wafer stealth dicing.

As a keystone instrument on the Fengyun-3C (FY-3C) satellite, the medium resolution spectral imager (MERSI) provides global coverage of top-of-atmosphere radiances for a broad range of scientific studies of the earth system. Based on the onboard measurements of the blackbody (BB) and deep space view (SV), the modified radiometric calibration equation was first given for the MERSI thermal emission band. The accuracy of the radiometric calibration was evaluated by comparing the average irradiance corresponding to the spectral response function and the irradiance corresponding to the wavelength, whose relative error was <0.40 % . Moreover, the BB-derived brightness temperature T_R calculated by the BB irradiance shows a systematic error relative to the BB equivalent temperature T_E obtained by the voltage code values of seven platinum resistors, and the value of T_R was lower 0.25 K than that of T_E. To further verify the validity of the calibration coefficient, the influences of the BB temperature, wavelength, and emissivity offsets on the derived irradiance and temperature of the earth were analyzed in detail. For the BB temperature changing by 0.10 K, the absolute values of the earth irradiance together with its equivalent temperature were 0.01 Wm ^{− 2} sr ^{− 1} μm ^{− 1} and 0.10 K, respectively, whose relative errors were about 0.16% and 0.40%. When the BB wavelength and emissivity changing by 0.1 μm and 0.005, the variations of the earth irradiance were 0.02 and 0.04 Wm ^{− 2} sr ^{− 1} μm ^{− 1}, respectively, whereas the relative errors of the equivalent temperature were 0.07% and 0.11%. These works provided an important theoretical guidance for the satellite data assimilations along with the quantitative remote sensing applications.

Glass bending is an important process in glass device manufacturing, and real-time stress detection is essential for regulating bending mold pressure. A three-point bending experiment is used to simulate the glass cold bending forming process, and the feasibility of the photoelastic method to detect the real-time bending stress in the pure cold bending state is analyzed. The conventional division-of-amplitude polarimeter is optimized to obtain a smaller spot diameter, fewer system conditions, and a wider stress detection range. The Stokes parameter error of the optimized system is 0.05, and the optical path difference measurement accuracy is 4.284 nm. The test quality of the photoelastic stress detection system during the three-point bending was not affected by the glass size or bending span. However, the various curvatures of the incident surface were found to cause different stress values in unloaded glass and fluctuations in y-values (the distance from the test beam to the neutral surface of the glass) to occur outside the normal range. The less the curvature of the glass is, the closer it is to normal incidence, and the more accurate the stress value is. After the heat treatment of the borosilicate glass, the experimental results show that the isotropic structure of the glass does not change significantly. The exploration of testing quality of bending stress provides an effective reference for practical high-precision bending glass manufacturing.

We aim to report an error analysis on single-shot profilometry when projecting a composite colored fringe pattern onto a surface containing different colors. Several studies have analyzed white surfaces using profilometry; however, when color is incorporated, new considerations must be taken into account. In this work, it is found theoretically and corroborated experimentally that each color introduces local phase variations that render in phase errors with a severity that is related to the crosstalk matrix of the projector–camera system. It is also shown that the phase errors are phase-shifting dependent and could be reduced with appropriate phase recovery algorithms. Experimental results are presented and compared with those obtained using a standard temporal four-step phase-shifting method.

In the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) project, the fiber should precisely align with the celestial target to obtain the spectrum of the star, and the position accuracy of the fiber in the focal plane directly affects the spectral quality. LAMOST uses photogrammetry to acquire the actual position of the fiber. However, the fiber view camera system without precise internal control points in the focal plane negatively affects measurement precision. To solve this problem, we propose a fiber position measurement method based on the external planar target (EPT) that replaces the internal control points with the external control points; multiview reconstruction and bundle adjustment with additional position constraints are used to calculate the position of the fibers. The validity of the measurement method is verified by the simulation and experiment. The preliminary results show that the method has good stability and the measurement accuracy of the fibers can reach 20 μm. Because the external control points are distributed on the EPT plane, the assembly error of the EPT and focal plane does not affect the measurement accuracy. Therefore, the proposed method can achieve precision measurement under nonprecision installation conditions.

Phase-shifting profilometry (PSP) is considered to be the most accurate technique for phase retrieval with fringe projection profilometry (FPP) systems. However, PSP requires that multiple phase-shifted fringe patterns be acquired, usually sequentially, which limits PSP to static or quasistatic imaging. We introduce color FPP (CFPP), which provides three-dimensional (3D) imaging using a single acquisition, for the application of real-time profiling. A single frame acquisition provides all three phase-shifted fringe patterns needed for the PSP phase retrieval algorithm. However, some problems must be overcome in CFPP, namely, color coupling and imbalance. Following up on the study, we propose a fixed coefficient decoupling method based on point-to-point correction and then introduce the empirical mode decomposition algorithm to decompose a color fringe pattern into three high-frequency components and three low-frequency components for imbalance correction, which improves measurement accuracy and realizes a single frame measurement for complex and discontinuous objects. After correction by the proposed method, the shape of the tested object can be recovered by one a single frame color fringe pattern, which meets the need for dynamic measurement, and the accuracy is not limited by the movement speed of object. The simulations and experimental results show that the proposed method can significantly reduce the influence of color coupling and imbalance in CFPP, and thus realize dynamic and high-precision 3D reconstruction.

Light-field cameras are gaining attention for their unique light gathering and post-capture processing capabilities. In our previous work, we combined light-field imaging with structured light technology to realize three-dimensional (3D) reconstruction for highly reflective surface. However, due to the lack of effective calibration of the light-field camera and reconstruction systems, it cannot meet the requirements of precise 3D measurement. A universal sub-aperture image extraction algorithm for the light-field camera with hexagonal microlens is presented to accurately extract the multidirectional images. Then, we explore the spatial relationship in equivalent camera array (ECA) of focused light-field camera according to the perspective variation of sub-aperture images. After that, an accurate 3D measurement system based on ECA model is proposed to achieve 3D measurement for highly reflective surface. To test the system’s practical performance, a precision analysis is conducted for a standard gauge block with ground truth. By comparing the reconstruction result of traditional method and ours, we demonstrated the validity of the proposed method to perform 3D measurement for highly reflective surface.

Spherical aberrations of lenses lead to increased spot radii on the focal plane. Several methods, such as optimizing thickness and radii or building lens groups, are known to minimize these spherical aberrations. Here, an innovative method for spherical aberration minimization is introduced; it can be used for short-range free-space optical communication systems, such as unit power afocal relay trains, lens waveguides, and periodic lens systems. This spherical aberration compensation principle is based on the combination of two identical spherical convex lenses at an optimal distance. Due to the higher refractive power for rays with an larger axis distance, rays from the outer area of the first lens intersect the inner area of the second lens, and vice versa. With this setup, the radial refractive power deviation of the two lenses compensate each other. Analytic calculations and numerical simulations are done to confirm this behavior, and measurements using two symmetric spherical lenses with polymer optical fibers as light feed confirm the calculations. Simulations and measurements show a very good matching behavior except for an unknown systematic error. At a lens distance of 300 mm, the optical attenuation decreased by ∼2 dB compared with a very small lens distance. This leads to the conclusion that this proposed spherical aberration minimization method works as theoretically predicted.

A zoom system named liquid-filled micro-cylindrical lenses integrating a capillary and a biconvex micro-cylindrical lens in a polydimethylsiloxane (PDMS) substrate is designed, which can achieve continuous changed focal length from 2.675 to 9.012 mm by injecting variable concentrations of glycerol aqueous solution into the capillary. The aberration fan diagrams, root mean square spot radius, peak-to-valley wavefront aberration, and modulation transfer function curves at different zoom configurations of the liquid-filled micro-cylindrical lenses are all analyzed, showing good imaging quality over the whole focal length range. And an anamorphic zoom system for uniform collimated beam is designed putting such two PDMS substrates similar as the Kepler telescope structure. The anamorphic system can realize the zoom shaping function with 1:2 to 2:1 aspect ratio beam conversion without machine movement along optical axis and with no significant aberration. The introduced zoom system is characterized by high image quality, small volume, and a simple and stable structure, providing a design idea for cylindrical lenses with variable focal length.

Lighting gel filters are widely used in commercial industries, but their adoption in scientific applications is limited, despite their low cost and form factor advantages. Here, we compare the optical performance of lighting gel filters to commonly used dielectric and colored glass filters in terms of absorbance spectra, passband transmission, angle of incidence dependence, autofluorescence, and photostability. Further comparison is performed in both preclinical and clinical imaging applications. The results show that gel filters might be a superior filter choice in several optical systems, including compact designs and fluorescence imaging applications. Compact designs using gel filters could have a significant advantage for applications such as point-of-care diagnostics, smartphone device add-ons, and single-use fluorescent assays.

Carbon dioxide (CO₂) is an atmospheric trace gas; therefore its accurate sensing is of great interest. Optical sensors exploiting the midinfrared (mid-IR) light absorption of CO₂ provide high sensitivity and are widely used in medical diagnostics, atmospheric monitoring, remote sensing, and industrial applications. In this work, we demonstrated accurate CO₂ gas sensing at a 4.2-μm wavelength. In addition, detecting the weak mid-IR molecular absorption bands of gases at low concentrations requires using increased optical path lengths. The most obvious method that can expand the potential beam path in a spectroscopic system is to use a longer linear gas cell, which in some situations may be adequate; however, space and volume requirements need to be considered. A circular multireflection (CMR) cell was used to reflect the radiation back and forth through the sample medium multiple times, thus greatly reducing the size footprint compared with a linear cell of equivalent optical path length. A CMR cell was designed and constructed to allow for multireflections within the cell. The optical alignment of the cell and the convenience of changing the optical path length by adjusting its position with respect to the incident light beam were also used to maximize the advantages of the device. The cell has an inner diameter of 6.5 cm, and the path length can reach up to 123.5 cm, which is equivalent to 19 beam passes of reflections. This work will be used as the groundwork for designing an instrument for the high-resolution measurement of CO₂ gas in planetary atmospheres.

We report on the Falcon neuro event-based sensor (EBS) instrument that is designed to acquire data from lightning and sprite phenomena and is currently operating on the International Space Station. The instrument consists of two independent, identical EBS cameras pointing in two fixed directions, toward the nominal forward direction of flight and toward the nominal Nadir direction. The payload employs stock DAVIS 240C focal plane arrays along with custom-built control and readout electronics to remotely interface with the cameras. To predict the sensor’s ability to effectively record sprites and lightning, we explore temporal response characteristics of the DAVIS 240C and use lab measurements along with reported limitations to model the expected response to a characteristic sprite illumination time-series. These simulations indicate that with appropriate camera settings the instrument will be capable of capturing these transient luminous events when they occur. Finally, we include initial results from the instrument, representing the first reported EBS recordings successfully collected aboard a space-based platform and demonstrating proof of concept that a neuromorphic camera is capable of operating in the space environment.

We propose an orthogonal frequency division multiplexing multiple-input/multiple-output space-frequency block-coded (MIMO-SFBC) system based on the exponential Weibull distribution model for uplink and downlink satellite laser communication. Considering the different effects of atmospheric turbulence on the laser beam, the closed expression of bit error rate (BER) was derived for the proposed system. The relationship between the BER and signal-to-noise ratio was analyzed under uplink and downlink, respectively, and compared with the single-input/single-output and space-time block-coded systems. Simultaneously, the effects of different numbers of transmitting and receiving antennas on the selection of zenith angle, receiving aperture, transmitting radius, and beam divergence of the MIMO-SFBC system were also studied. Finally, the Monte Carlo method was used to verify the experimental data. This study provides a theoretical reference for the engineering implementation of MIMO coding technology in satellite laser communication systems.

In visible light communication (VLC) systems, many adopted optoelectronic devices, such as light-emitting diodes (LEDs) and photodiodes, exhibit nonlinear characteristics that limit the system performance. Meanwhile, the high peak-to-average power ratio induced by orthogonal frequency division multiplexing modulation aggravates the nonlinear distortion, so mitigating the nonlinear distortion effects is desired. Aiming at the nonlinear characteristics of LEDs, we employ radial basis function (RBF) interpolation and propose a postdistortion method by combining RBF with memory effect depression (MED), which effectively suppresses the nonlinear and memory effects of LEDs. Simulation results show that the proposed RBF-MED is beneficial to the nonlinearity compensation in the VLC system, and it can deliver a better bit error rate performance compared with commonly-used memory polynomial and Volterra schemes.

Drag reduction is one of the main problems in aircraft design and a meaningful way to save fuel and improve efficiency. Surface microgrooves can reduce the frictional resistance of aircraft walls and become one of the main ways to reduce aircraft drag. A nanosecond laser can prepare microgrooves. However, the recast layers under high laser energy during processing deteriorate the processing quality. How to improve processing quality while ensuring processing efficiency is a challenge. By replacing the target feature analysis model in the original genetic algorithm with an optimization target model based on the response surface method, this study proposes an optimization method for the nanosecond laser processing of the microgroove. This method uses the difficult-to-machine aerospace material TC4 titanium alloy as the target. The Box–Behnken design method is used to design the laser processing experiment of the microgroove. The validity and reliability of the proposed optimization method are verified. It is worth mentioning that the proposed method can obtain satisfactory optimization results with fewer parameter variables and fewer experiments, with low experimental cost and high optimization efficiency compared to genetic algorithms. Furthermore, the optimized process parameters will provide initial parameters for the high-quality preparation of large-scale microgrooves on the TC4 surface through the nanosecond pulsed laser layer-by-layer scanning processing way. And the optimization method is suitable for optimizing short-pulse and long-pulse laser processing parameters of microgrooves on metal surfaces and has practical engineering value.

The bonding technology of carbon fiber-reinforced plastic (CFRP) is a key technology in its production. Laser pretreatment is a common method for improving the bonding strength. However, the use of laser pretreatment without damaging the carbon fibers has always been challenging. A laser pretreatment method is proposed to improve the bond strength of CFRP without damaging the carbon fibers. The proposed method increases the tensile shear strength of CFRP from 2448 to 4851 N; 9.79 to 19.41 MPa. The naked carbon fiber treated by buffer laser pretreatment provides additional strength to the glue. Scanning electron microscopy was used to image the surfaces of the samples. Failure modes were also investigated to explain the increase in bond strength. The benefits of this method can be explained using a thermal model, and this method can be used as a reference for the laser processing of CFRPs.

A light fiber winding around a curved path model can generate a large vortex Bessel solitary wave (BSW). The spiral body structure BSW can carry orbital angular momentum (OAM) modes. We investigate the influence of curved path and the type of winding of the principal ray based on the OAM modes. The curve path corresponds to the intensity of the modes of the OAM beam. Our vortex BSW is different from traditional electromagnetic amplitude solitary waves. We calculate the propagating diffraction pattern in the optical fibers, and find that a fundamental BSW is an Airy spot. Along with increasing the order number, we also see that the vortex BSW decays gradually from the center to the exterior, and the BSW leaks more energy to the outer rings.

We demonstrate an efficient continuous-wave (CW) and Q-switched Tm:LuYAG laser that was resonantly pumped by an Er:LuYAG laser. The maximum CW output power was 3.12 W, and the corresponding slope efficiency relative to the incident pump power was 51.4%. In the Q-switched mode, a stable laser pulse was achieved from 1 to 10 kHz repetition frequency under the maximum incident pump power of 7 W. The narrowest pulse width of 94 ns with a pulse energy of 2.12 mJ was obtained at 1 kHz, resulting in the highest single pulse peak power of 22.5 kW. The Tm:LuYAG laser was centered at 2018.37 nm with a high-beam quality M² < 1.2.

The controllable self-accelerating and self-decelerating Airy–Ince–Gaussian (CAiIG) wave packets in strongly nonlocal nonlinear media are investigated theoretically and numerically by solving the (3 + 1)D Schrödinger equation in cylindric coordinates. Typical examples of the obtained solutions are based on the ratio of the input power and the critical power as well as the initial velocity and the ellipticity. The CAiIG wave packets are constructed by the Airy pulses with initial velocity in temporal domain and the controllable Ince–Gaussian (IG) beams in spatial domain. Self-decelerating and self-accelerating CAiIG wave packets are obtained by selecting different initial velocities. The CAiIG wave packets keep approximately nondispersion properties in temporal dimension. However, the width of packets periodically oscillate or keep steady in spatial dimension according to the ratio of the input power and the critical power. The transverse field patterns of the CAiIG wave packets are manipulated by the IG wave packets, meanwhile the Airy pulses affect their transverse amplitudes. For the self-accelerating CAiIG wave packets, the transverse intensity decays during the propagation. However, to the self-decelerating CAiIG wave packet, the transverse intensity initially vibrates then decays. The direction of the energy flow of CAiIG wave packets in spatial domain periodically changes from the propagating center if the ratio of the input power and the critical power is not equal to 1, which causes the CAiIG beams periodically oscillating during propagation. Their Poynting vector snapshots at different propagating distances are shown.

The transmission T and internal losses L of a non-planar ring oscillator (NPRO) laser are measured using a unique approach. Measurement of slope efficiency, axial mode separation, and relaxation oscillation frequency as a function of NPRO output power are all used in this procedure. T was assessed to be 2.3%, which was significantly higher than the supplier’s given value of 1.7% for a 32-deg angle of incidence at the NPRO output coupler at 1064 nm. The estimated value of internal loss was 4.2%.

We propose and demonstrate a highly sensitive optical fiber sensor for vibration and twist based on a polarization-sensitive effect of mode selective coupler (MSC). MSC is prepared by melt coupling. Based on the polarization sensitivity, high sensitivity testing of twist and vibration is realized. The proposed MSC can be used for twist sensing with different demodulation methods at the same time, including intensity of spectra and modes. The twist sensitivity is –10.383 a.u./deg ( ∼ −0.02 dB / deg). For vibration sensing, the MSC achieves ultrabroadband sensing frequency response span from infrasound (Hz) to ultrasound (MHz) with good fidelity and high linearity of ≈ 1. The signal-to-noise ratio of single- and dual-frequency vibration detection is as high as ∼108 dB. In addition, the MSC can realize the detection of damped vibration signals steadily. The twist and vibration sensor based on MSC have the advantages of high sensitivity, wide frequency response range, good linearity, high stability, high fidelity, and compact structure. It has potential application prospects in the fields of oil field leakage detection, coal mine, and other structural safety monitoring.

A D-shaped photonic crystal fiber (PCF) low refractive index (RI) sensor based on surface plasmon resonance (SPR) is proposed, and its properties are investigated by the finite element method. Gold is selected as the plasmonic material and coated on the open-ring structure to excite the plasmonic modes. The simulation results indicate that the sensor can detect the RI in the range of 1.00 to 1.29, which is a fairly wide detection range in the detection field of SPR-based PCF low RI sensors. When the analyte of the RI varies from 1.28 to 1.29, the maximum sensitivity of 10,000 nm / RIU and the corresponding resolution of 1 × 10 ^{− 5} RIU are obtained in the wavelength range of 1.6 to 2.4 μm. When the RI of the analyte changes from 1.00 to 1.29, the relationship curve between the RI and the resonance wavelength fits well, and the adjusted R² value is 0.99609. Furthermore, the sensor achieves the figure of merit of 56.98 RIU ^{− 1} and an amplitude sensitivity of 82.76 RIU ^{− 1}, respectively. Therefore, the designed sensor can be effectively applied to low RI detection, having a certain commercial potential in medical detection, organic chemistry detections, and related applications.

A dual-core D-shape photonic crystal fiber sensor based on surface plasmon resonance is designed and analyzed numerically by the finite element method employing the perfectly matched layer boundary conditions. The resonance peaks shift as the analyte refractive indexes are varied. An average sensitivity of 17,200 nm / RIU is achieved in the RI range between 1.40 and 1.44 and the corresponding resolution is 5.8 × 10 ^{− 6} RIU. The various factors affecting the sensing properties are assessed and in particular, the combined effects of two variables are evaluated.

On-chip filters are widely used in integrated optical systems and are indispensable for expanding the communication capacity. A silicon waveguide filter is fabricated into a subwavelength Bragg grating structure using the optical phase-change material Ge₂Sb₂Se₄Te₁ (GSST). Three-dimensional finite-difference time-domain method simulations showed that this structure performed multichannel filtering in the communications C-band (1530 to 1565 nm), demonstrating a minimum insertion loss of 0.238 dB and a full width at half-maximum of 3.4 nm with an incident TE0 mode. The number and width of channels can be adjusted using structural parameters. Furthermore, the overlapping frequencies of passbands and stopbands are obtained by the phase transition of GSST. This structure could potentially find use as an optical signal modulation device in on-chip integrated systems.

Silicon nanophotonics is contributing to the development of devices with small dimensions and low energy consumption. In optical systems for space applications, whether in large or small satellites, such as CubeSat, the demand for photonic devices has been a necessity, mainly in the communication subsystem, due to limitations in the conventional optical beam pointing subsystems. Silicon nanophotonics can be a solution in this case as it allows for the construction of an optical beam pointing system without moving parts, such as optical phased array antennas, in which the component responsible for the pointing functionality is the optical phase modulator. With this objective, we propose an efficient non-resonant all-optical modulator based on an Archimedean spiral waveguide topology by means of the indirect thermo-optical effect. Computational results are presented and discussed.

Due to the capability of achieving versatile control of differently polarized electromagnetic waves, anisotropic metasurfaces have attracted extensive attentions. To manipulate terahertz waves flexibly, we propose a tunable anisotropic metasurface based on phase change material vanadium dioxide (VO₂). It is composed of a gold bottom layer deposited on the back of polyimide dielectric layer and a gold patch located on the front of the polyimide dielectric substrate. When VO₂ is in the insulating state, the predesigned metasurface produces diversified functions, including terahertz beam splitting, deviation focusing, and multivortex beam under different polarization terahertz wave incidence. When VO₂ becomes a metallic state, the proposed metasurface changes the number of terahertz beams, the shape of vortex beams, and the focusing effect. This scheme provides an innovative idea for the dynamic regulation of the terahertz wave in future terahertz technology systems.

Serious nonradiative recombination and decomposition of perovskite film exist in MAPbBr₃-based perovskite light-emitting diodes (PeLED) due to the residue of lead atoms from an incomplete reaction, thereby limiting the efficiency of PeLEDs. Excessive Methylammonium bromide (MABr) added into the precursor of methylammonium lead bromide (MAPbBr₃) can solve this problem. However, how the excessive MABr self-passivates perovskite films improves the performance of PeLEDs requires further examination. The self-passivated perovskite film by overdoping MABr was investigated by varying stoichiometric ratios of perovskite precursors. It was found that, as the content of MABr increased, the interaction between free charge and longitudinal optical phonons was enhanced, thus reducing the exciton binding energy, resulting in emission broadening and blue shift of the PL spectra. With the molar ratio of PbBr₂ and MABr of 1:1.315, the PeLED achieved a good trade-off between the brightness and the stability, thus demonstrating a maximum brightness of 9981 cd m ^{− 2} and a lifetime of 14 min, with a maximum current efficiency of 6.59 cd A ^{− 1}.

A hybrid metamaterial based on a metal-solid-state plasma (SSP) structure has been demonstrated, which actively controls the transparency window by introducing the SSP. The unit cell consists of square patch with a slot and metal cut wire (CW) with SSPs embedded. The designing of a resonant frequency tuning is intrinsically more difficult than amplitude modulation, which has been extensively researched. By introducing SSP and sophisticated structural design, the frequency shifts 403 GHz when the structure switches between two states. The transmission window is switched by changing the state of SSP, allowing for a dynamical group delay of the terahertz frequency. The linearly coupled Lorentz oscillator model is utilized to explore the underlying mechanism of the actively tunable electromagnetically induced transparency behavior between the bright and bright modes. We provide fascinating possibilities for innovative optical components in certain areas, including ultrafast switching, sensing, and terahertz active filtering.

The erratum makes an addendum to the last line of the paper to include two additional references.

Erratum contains the addition of a reference that was omitted.