One of the most important missions of an airborne inertial stabilization platform (AISP) is to acquire the image of the target with high resolution. It is challenging for the AISP to acquire such high-quality images because the AISP is continuously exposed to a significant level of vibration from the airplane, which is transformed into exogenous disturbance torque. As a consequence, the AISP suffers line-of-sight jitter that undermines the image quality. Although the conventional mass stabilization system is capable of rejecting exogenous disturbance torque only within a low frequency band, the introduction of a fast steering mirror (FSM) can significantly expand the disturbance rejection capacity. This paper describes how the introduction of the FSM improves the image stabilization capacity. On top of the conventional mass stabilization system of gimbaled mechanism with inertial sensor feedbacks, we implement the FSM that covers high frequency band within the optical path from the telescopes of the AISP to its image sensor. A high gain FSM controller is designed through the loop-shaping method and applied to the piezo-electric actuator driven FSM, which shows a sufficiently high bandwidth for rejecting the exogenous disturbance of our interest. The results from both actuation data and acquired images demonstrate the effectiveness of the FSM in the image stabilization of the AISP.

Structured illumination microscopy (SIM) has emerged as a powerful technique, surpassing the limitations imposed by optical diffraction and providing remarkable enhancements in both lateral and axial resolution compared with traditional diffraction-limited microscopy. However, it does come with certain limitations, including the need for a complex optical setup, extensive image acquisition, and computationally intensive post-processing. Motivated by the advancements in deep-learning-based super-resolution techniques, we propose an original three-dimensional (3D) representative learning algorithm called the transformer-based generative adversarial network (TransGAN), which can accurately predict corresponding aberrations through a combination of 17 mixed Zernike modes. Our approach outperforms state-of-the-art algorithms in various cellular structures, achieving impressive results with a mean square error of 2.358×10−5 for aberration determination. TransGAN presents a promising solution for enhancing SIM imaging, offering improved resolution and precise aberration estimation. This technique exhibits significant potential in overcoming the limitations associated with 3D SIM techniques and advancing the field of 3D optical microscopy.

In measuring a transmission matrix (TM) of a scattering medium, the normal way requires projecting a large number of patterns, resulting in significant measurement time. Here, we propose to do imaging through scattering media using a path-planning-based downsampling TM. The proposed method is verified by measuring TMs for imaging through scattering media when Walsh, Cake-cutting, and Russian doll Hadamard transforms (HTs) are adopted. Based on the spectral characteristics of different HTs of natural images, corresponding sampling paths are artificially planned, which guarantees the method to preferentially measure components in TM in relation to the more important spectra. This means that our method can reduce the number of patterns during measurement, thus improving the imaging speed while only sacrificing a little imaging quality. Experimental results demonstrate the effectiveness of the proposed method.

In this work we apply an optical system with two cascaded liquid-crystal spatial light modulators (LC-SLMs) to produce multiple outputs with intensity and polarization control. We use a non-standard modulation configuration where the first LC-SLM operates as a phase-only modulator to encode a Fourier transform hologram multiplexing the desired multiple output beams, all with the same polarization. Next, the Fourier transform is optically formed onto the second LC-SLM, where each output beam is focused on different physical locations. The two SLMs have the LC director axis oriented horizontally. Thus, by rotating the linearly polarized output beams emerging from the first LC-SLM by 45 deg, we operate the second LC-SLM as a variable retarder. Then, by applying different phase-shifts at the different areas of the second LC-SLM, we can vary the polarization state of each output beam. Finally, the output is imaged onto a camera detector to demonstrate the polarization states. Experimental results demonstrate the capability for this approach to encode a variety of output beams with different states of polarization.

Growing awareness of the adverse health effects of air pollution has increased the demand for reliable, sensitive, and mass-producible sensor systems. Photothermal interferometry has shown great promise for sensitive, selective, and miniaturized gas sensing solutions. This work describes the development of a macroscopic photothermal sensor system with a sensor head consisting of a low-cost, custom-made, and fiber-coupled Fabry–Pérot etalon. The sensor was tested with NO2, achieving a 3σ limit of detection (LOD) of approximately 370 ppbv (1 s). Exhibiting little drift, a LOD of 15 ppbv is achievable for 200 s integration time. Compensating for the excitation power, the normalized noise equivalent absorption was calculated to be 1.4×10−8 cm−1WHz. The sensor system is not limited to NO2 but can be used for any gas or aerosol species by exchanging the excitation laser source.

To address the difficulty of balancing dynamic performance and spatial bandwidth in existing low-coherence digital holography (DH), the parallel phase-shifting method used in coherent and incoherent DH is introduced into low-coherence DH. A light-emitting diode (LED)-based reflective optical configuration of the proposed phase-shifting low-coherence DH is designed. The speckle noise, zero-order diffraction, and twin image noise are suppressed by the low-coherence LED source and the four-step phase-shifting method. Simulation and optical experimental results demonstrate that the proposed method can simultaneously achieve high-precision, high-resolution, full-field, single-shot amplitude and phase imaging. It is expected to be applied to many fields such as flow cytometry imaging and micro-electromechanical system detection.

By classifying crops using machine learning approaches, it is possible to determine if the spectral signatures of several variations of the same species differ from one another. This allows for the correlation of the spectral signatures with key properties of the finished product. The final cannabinoid content of a certain species is a crucial quality attribute that might raise the crop’s value in the case of Cannabis growing. In contrast to conventional cutting and laboratory analysis approaches, the classification of Cannabis varietals from spectral signatures is proposed as a nondestructive process. The findings demonstrate that a random forest classification algorithm optimized on hyparameters can classify four types of Cannabis grown in Colombia with a multiclass accuracy of 95.6% using the spectral signature. These findings will make it possible to determine whether the spectral signature is related to the cannabinoid content of the various kinds, which is crucial for medical purposes.

Laser manufacturing of aluminum and titanium alloys is gaining interest in the automotive, aerospace, and defense industries due to its diverse applications. Laser interaction with these alloys involves heating, melting, and evaporation, with evaporation being critical. Selective vaporization of certain elements in multi-element alloys can affect stoichiometry. In-situ monitoring of the ejected plume helps control the product quality. Optical emission spectroscopy (OES) characterizes the plume constituents and provides information about the excited states. Our study uses high-speed imaging (HSI) and OES to monitor the laser interaction process with AlMg5 and Ti6Al4V alloys. OES analysis reveals a higher rate of magnesium evaporation compared with aluminum during the millisecond laser interaction with AlMg5, a trend that intensifies with an increase in laser power and a decrease in speed. On the other hand, the selective evaporation of magnesium in comparison with aluminum during the nanosecond laser interaction with the AlMg5 alloy is negligible, indicating no effect on stoichiometry. During the interaction between the millisecond laser and the Ti6Al4V alloy, titanium is found to evaporate more compared with aluminum, despite the higher boiling point of titanium relative to aluminum. This behavior contrasts with that of the AlMg5 alloy. HSI reveals an increase in spatter and laser-plume interaction with increased laser power and decreased speed during millisecond laser interaction with AlMg5. In-situ monitoring during single-shot millisecond laser interactions is conducted in a controlled manner with and without Ar gas shielding. The detection of oxidation in the absence of shielding gas through OES analysis highlights its potential for process monitoring.

The enormous amount of time required to generate hologram data in electro-holography is a problem that hinders real-time display of holographic video. With the aim of achieving holometric video streaming that enables volumetric video streaming by holography, we propose a method for correcting calculations of cylindrical object light using a graphics processing unit and generating electro-holography in accordance with observer movement in real time. We confirmed through experiments using an optical system that the proposed method enables real-time 360-deg panoramic views of three-dimensional video for multiple users.

The climate on Earth is affected by the Sun. It is thus necessary to determine the solar spectral irradiance (SSI) with high precision on the ground for the improved accuracy of climate models used for Earth. To achieve this purpose, a solar spectral irradiance monitor (VISM) with a wavelength ranging from 380 to 2400 nm is developed. In this work, the optical design and spectral calibration of the VISM are explored, with two optical paths designed to determine the SSI in the wide spectral region. One of them is the main optical path through which the sunlight is dispersed and imaged by a single Féry prism. A laser and a concave mirror are used in the other optical path to determine the rotated angle of the Féry prism, which is crucial to determining the spectral information. Furthermore, a new spectral calibration method is developed for VISM. According to this method, the dispersion equation of the prism is combined with the results of three characteristic wavelengths to determine the relationship between the dispersed wavelengths and the pixels in the detector for the whole spectrum. An apparatus is set up in the laboratory for spectral calibration. It is revealed that the uncertainty of spectral calibration is about 0.3 nm, which exceeds the design requirement. When the designed VISM works outdoor, the SSI can be determined readily. It is shown that the optical design and spectral calibration proposed in this study for VISM are correct.

A systematic standard for developing light extraction technologies that can improve the efficiency of lighting systems based on the optical design method of flat-type lighting devices needs to be established. The design of a flat-type lighting device was investigated, considering the utilization of precise processing techniques that simplify the manufacturing process. These techniques adjust the processing variables of the geometric pattern of the light guide plate (LGP), light-emitting diodes (LEDs), which are placed on the sides of the LGP, and viewing angle. The amount of light lost was reduced by etching the light-incident surface of the LGP as a curved shape. A pattern spacing of 9 mm was used to control four LEDs placed in the middle of each side of the LGP with a viewing angle of 120 deg and four LEDs placed at the corners with a viewing angle of 60 deg. In addition, hotspot generation was prevented by controlling the amount of light concentrated in the light-incident area, and the illuminance uniformity of the LGP was confirmed to be 95%, showing an improved optical efficiency. By controlling only the pattern spacing, position of the light source, and viewing angle of the LEDs, the optimal design conditions to improve the optical efficiency of the flat-type lighting device were established. It was found that these parameters can sufficiently improve the imbalance caused by the concentration and loss of light.

We propose an all-optical design of NOT, AND, OR, one-bit half adder, and subtractor using a microring resonator-based 2:1 multiplexer. As a substitute for traditional CMOS technology, the sector is moving toward large-scale optical integrated circuits due to growing needs for ultraspeed terahertz data transport and processing. Furthermore, energy-efficient connections are becoming more and more crucial. Using MATLAB, the complete design is thoroughly simulated and verified at an operational speed of nearly 260 Gbps. The faster response times of the suggested multiplexer-based circuits make them especially useful for digital signal processing and communication systems. Also performance parameters, such as the “extinction ratio,” “contrast ratio,” “amplitude modulation,” “on–off ratio,” “quality factor,” “photon cavity lifetime,” and “relative eye opening,” are estimated. Circuit parameters that are optimized are chosen to construct the circuit practically.

For indoor visible light communication system, the layout of light-emitting diode light sources affects the illuminance uniformity (UIR) and communication reliability of the system. We took a 5 m×4 m×3 m room as the model. The annular light source layout is designed and compared with the traditional circular layout. The simulation results show that the illuminance performance and communication performance of the annular layout are better. The genetic-ant colony hybrid algorithm is used to optimize the position and power of the light source of the annular layout. The UIR and quality factor Q are improved by 15.49% and 61.39% after optimization, respectively. Then, an experimental system of annular layout is built. Compared with the simulation results, the error of UIR obtained by the experiment is 4.21%. The equipment for the illuminance test is also used to connect to an indoor visible video transmission system, which proves the feasibility of an annular light source layout.

We present a compact end-side pumped solar laser concept designed to enhance efficiency in both multimode and TEM00-mode operations. The primary concentrator, a 1.0 m diameter off-axis parabolic mirror, efficiently collects and focuses solar rays into the laser head, which consists of a large fused-silica aspheric lens secondary concentrator, a conical-shaped pump cavity, and a single Nd:YAG crystal rod. Optimization of the solar laser system parameters was carried out using ZEMAX^© for nonsequential ray tracing and LASCAD^© for laser cavity analysis. Since our study is part of a solar laser project in desert regions of Algeria, 1200 W/m2 solar terrestrial irradiance was assumed, our numerical simulations achieved 38 W continuous-wave laser power in multimode operation, for a 5 mm diameter, 25 mm length Nd:YAG rod. This corresponds to a collection efficiency (CE) and solar-to-laser conversion efficiency (CVE) of 48.40 W/m2 and 4.03%, respectively, being 1.50 and 1.22 times higher than the previous experimental records of a single-beam Nd:YAG solar laser. For 980 W/m2 solar irradiance, 29.72 W laser power was calculated, leading to 37.84 W/m2 CE and 3.86% laser CVE, respectively, being 1.18 and 1.17 times more than previous experimental records. For TEM00-mode operation, utilizing a thin Nd:YAG laser rod with an adjusted pump cavity and optical resonator enabled efficient extraction of a fundamental-mode solar laser beam with a very high-quality factor (M2≤1.02). 15.63 W TEM00-mode laser power was obtained, corresponding to a CE of 19.91 W/m2, which is 2.52 and 1.86 times higher than the previous experimental and numerical records, respectively, of a single-beam Nd:YAG solar laser. By assuming 980 W/m2 solar irradiance, 10.64 W TEM00-mode laser power was numerically achieved, resulting in 13.55 W/m2 CE and 1.71 and 1.26 times enhancement than that of the previous experimental records by a single-beam Nd:YAG solar laser.

We proposed and experimentally validated an all-fiber probe based on the fusion splicing of multiple fibers, designed to capture the cells or microparticles. Introducing the 980 nm laser into the optical fiber and shaping the beam with the probe, which was fabricated by coaxially splicing the no-core fiber (NCF) with the graded-index (GRIN) fiber onto the single-mode fiber (SMF), created a light trap. (We took the first letters of three types of fibers and named it SNG probe.) The focusing effect of the Gaussian beam was tuned by matching the lengths of the NCF and GRIN to achieve optical trapping of particles. We simulated the optical field of the SNG all-fiber optical tweezers (AFOTs) and the dynamic force distribution of microparticles at different positions within the optical field. We also developed a numerical analytical model of the OTs to analyze the effect of fiber length on the capture performance. The output optical field distribution of the SNG AFOTs was experimentally tested, confirming the capability of this fiber tweezer for non-contact and long-distance capture of yeast cells (more than 240 μm). This type of OTs has the potential to advance relevant research in biology and chemistry.

This paper investigates a multiple-input multiple-output dual-hop underwater visible light communication (UWVLC) system with decode and forward (DF) relay, considering turbulence-induced fading and path loss. Our research aims to analyze the performance of this system under weak oceanic turbulence, featuring M laser sources at the transmitter and N detectors at the destination. We model the UWVLC channel using a log-normal distribution and employ one laser diode and one photodetector at the relay. By selecting the optimal laser source and photodetector based on maximum instantaneous signal-to-noise ratio (SNR), we derive the cumulative distribution function (CDF) of the end-to-end SNR. Utilizing this CDF expression, we provide closed-form expressions for outage probability and average symbol error probability (ASEP) using Gauss–Hermite quadrature techniques for the rectangular quadrature amplitude modulation scheme. We analyze ASEP for different constellation points with M sources and N photodetectors and present simulation results demonstrating ASEP versus average SNR, as well as outage probability versus average SNR, showcasing close agreement with analytical predictions. Moreover, we offer insights for system designers by presenting a trade-off between constellation points and the number of lasers, along with the number of photodetectors, to optimize system performance.

The vital gases carry through the hemoglobin; hence, the detection and analysis of hemoglobin concentration are crucial in the physiology processes. In this context, we introduce a biosensor based on a one-dimensional photonic crystal with a defect layer for oxygen sensing in hemoglobin. In this innovative approach, hemoglobin is the defect layer and its refractive index changes with oxygen dissolution. The variation of the refractive index leads to a shift in the transmission spectrum, which can be utilized to distinguish between oxygenated and deoxygenated hemoglobin. The theoretical investigation of transmission spectra using the transfer matrix method reveals that both hemoglobin states can be effectively distinguished. The proposed sensor exhibits remarkable sensitivity, particularly with the optimum structure featuring a defect layer thickness of 12 μm, seven layers, and an incident angle (θ) of 81 deg, providing a sensitivity of 1510.5 nm/RIU. These findings underscore the high-performance potential of our sensor in the region of oxygen sensing in biology, particularly in medical applications.

Using modeling and computer simulation techniques, we conducted a comprehensive analysis of heat propagation processes and noise determination in a nanoscale three-layer detection pixel of a thermoelectric single-photon detector. The detection pixel comprises an absorber, a thermoelectric sensor, and a heat sink stacked on top of each other on a dielectric substrate. Our research was aimed at studying the spread of heat inside the detection pixel following the absorption of single photons with energies ranging from 0.8 to 7.1 eV (1550–175 nm) in tungsten or molybdenum absorbers of various thicknesses. The simulation was executed based on the equation for heat propagation within a limited volume. We explored temporal temperature variations in different regions of the detection pixel and analyzed the average temperature gradient across the sensor and heat sink surfaces. Parameters such as signal power resulting from the photon absorption, equivalent noise power, and signal-to-noise ratio were determined. Our results indicate that detection pixels consisting of W or Mo absorbers, a thermoelectric sensor La0.99Ce0.01B6, and a Mo heat sink, with a 15 nm thick absorber and a surface area of 1 μm2, can effectively detect single photons across a broad spectrum from far ultraviolet to near infrared. The calculated signal-to-noise ratios and temporal characteristics indicate the possibility of using this thermoelectric detection pixel design in optical microchips and large-scale multi-pixel cameras.

A photonic crystal fiber (PCF) polarization rotator, featuring a large bandwidth and low insertion loss (IL) and based on the mode hybridization principle, is proposed. By reducing the size of two air holes in the 45 deg inclined direction of the fiber core, a tilted lemon-shaped fiber core is constructed. This design breaks the vertical and horizontal symmetry in the cross section of the PCF, achieving efficient mode conversion between transverse magnetic and transverse electric modes. The characteristics are numerically analyzed using a full-vectorial finite-difference method with a perfectly matched layer boundary condition. The results show that, at a working wavelength of 1.55 μm, the device achieves nearly 100% polarization conversion efficiency, an extinction ratio of 43.3 dB, and an IL of 0.025 dB, with a mere device length of 291 μm. Additionally, the operational bandwidth exceeds 825 nm (1.096 to 1.921 μm), covering the entire range of current optical fiber communications, including the O, E, S, C, and L bands. It demonstrates a good tolerance and significant potential for engineering applications in informational photonics.

We discuss the design and the optimization of interband cascade infrared photodetectors (ICIPs) based on type-II InAs/GaSb superlattices. Our study explores matched-absorbers configuration in ICIPs made up of multiple stages. An effective and enhanced computational approach is presented for determining the subsequent absorbers thicknesses in the matched-absorbers configuration. The first absorber thickness controls that of the following active layers, ensuring uniform quantum efficiency (QE) throughout all stages. Thus, we have demonstrated that selecting the initial absorber thickness is an important factor that can improve the performance of ICIP detectors. Furthermore, we have established that the accurate calculation of the subsequent absorber thicknesses leads to a significant high QE, with potential improvements of over 80% in certain cases.

Extreme ultraviolet (EUV) light with a 13.5 nm wavelength plays a crucial role in many fields, such as microelectronics manufacturing and material science. However, conventional transmissive meta-optics designs for EUV light face great challenges due to the strong absorption of most materials and the near-unity real part of the refractive indices, which usually prevent waveguiding and effective refraction. Here, we numerically demonstrate the focusing of EUV light at 13.5 nm by the elaborately designed molybdenum (Mo) metalens based on the nanohole array. Compared with other candidate materials, Mo-based metalens sustains efficient propagation of the 13.5 nm EUV light through nanoholes milled on the membrane, leading to the focal spot with a diffraction-limited size of 46 nm and a focusing efficiency of 27.8%. In addition, the dependence of the focusing efficiency on the self-supporting Si or Si3N4 membrane is investigated. The proposed Mo-based metalens for the focusing of the 13.5 nm EUV light holds promising applications in semiconductor lithography, high-resolution imaging, and ultrafast spectroscopy.

A strictly non-blocking wavelength-selective photonic crystal (PC) router for mesh-based optical networks-on-chip (ONoC) that employs a novel crossed-waveguide structure as the routing basic unit is designed. The proposed router only consists of eight crossed-waveguides without the need for a ring resonator, and its entire structure is symmetrically distributed on the top, bottom, left, and right. When implementing the non-blocking routing function, the signal-to-noise ratio is 17.84 to 20.06 dB, and the insertion loss and crosstalk are 0.36 to 0.88 dB and (−50.3) − (−8.03) dB, respectively, when implementing the wavelength-selective routing function. Compared with existing non-blocking wavelength-selective PC routers used in ONoCs, this router not only exhibits strict non-blocking routing transmission characteristics but also has prominent features of a simple structure and easy implementation due to the absence of ring resonators. Furthermore, the proposed structure possesses good scalability and can be easily expanded to realize higher radix non-blocking optical routing systems, which have broad application prospects in ONoC.