High-resolution imaging with large ground-based telescopes is limited by atmospheric turbulence. The observed images are usually blurred with unknown point spread functions (PSFs) defined in terms of the wavefront distortions of light. To effectively remove the blur, numerical postprocessing with a good approximation of the wavefront is required. The gradient measurements of the wavefront recorded

For two decades, extraordinary optical transmission has amplified exploration into subwavelength systems. Researchers have previously suggested exploiting the spectrally selective electromagnetic field confinement of subwavelength slits for multispectral detectors. Utilizing the finite-difference frequency-domain method, we examine electromagnetic field confinement in both two-dimensional and three-dimensional

The dissipative soliton resonance (DSR) pulses are demonstrated experimentally in an all polarization-maintaining (PM) thulium-doped mode-locked fiber laser. The mode-locked operation is achieved using of the nonlinear amplifying loop mirror mechanism (NALM). Each loop of the apparatus includes an independently controlled amplifier and a section of gain fiber. The experiment is carried out at a central

In the beam control system, the correction of optical axis is an essential process of the optical system. Adjusting the installation angle of the relay mirror is an effective way to change the optical axis direction. However, due to the forced deviation of the installation angle from the theoretical design value, the supporting structure will produce greater stress, which will affect the surface accuracy

We proposed an adaptive two-stage nonlinear feedforward equalizer and decision feedback equalizer to minimize the negative influence of nonlinear distortions. A data rate of 960 Mbit/s is experimentally achieved on the guided visible-light transparent transmission over a 100-m ultra-large effective area pure silica fiber. The experimental results verified the effectiveness and improvement of the proposed

A high-capacity spectral-efficient dual-polarization quadrature phase-shift keying (DP-QPSK)-polarization shift-keying (PolSK) hybrid modulation scheme for terrestrial free-space optics (FSO) transmission link is proposed and investigated. A DP-QPSK signal modulated at 300 Gbps and a PolSK signal modulated at 40 Gbps are simultaneously transmitted using a single optical carrier over the FSO link. The

Detection of high-energy laser strikes is key to the survivability of military assets in future warfare. The introduction of laser weapon systems demands the capability to quickly detect these strikes without disrupting the stealth capability of military craft with active sensing technologies. We explored the use of thermoelectric generators (TEGs) as self-powered passive sensors to detect such strikes

Color conversion matrices and chromatic adaptation transforms (CATs) are of central importance when converting a scene captured by a digital camera in the camera raw space into a color image suitable for display using an output-referred color space. In this article, the nature of a typical camera raw space is investigated, including its gamut and reference white. Various color conversion strategies

Two-dimensional digital image correlation (2D-DIC) has the advantages of high computation efficiency and simple experimental setup compared to three-dimensional DIC (3D-DIC). However, 2D-DIC is sensitive to out-of-plane motion, which leads to rather poor strain results. Recently, optical extensometers realized by dual-reflector imaging have been proposed, which can self-compensate the strain errors

A hybrid plasmon waveguide (HPWG) consisting of a gold layer, a 100-nm high nanogap, and a SiN layer with a high refractive index on a SiO2 / Si substrate was designed by simulation and was applied in a Mach–Zehnder interferometer biosensor. For the incidence of a transverse magnetic (TM) mode light, a strongly enhanced electric field in the nanogap region caused by the modified surface plasmon enabled

In order to obtain reconfigurable topological photonic waveguides, we design a two-dimensional photonic crystal with compound triangular lattice. Through rotating the dielectric rods, we change the topological phase of the lattice and achieve the topological edge states. Through the rotation of rods, we divide the two-dimensional structure space into “0” and “1” blocks made of the topologically trivial

A graphene-sandwich metasurface for electrically controlled operation as a frequency shifter, a reciprocal switch, and a bidirectional isolator in the terahertz spectral regime was simulated using CST Microwave Studio™ 2019 software. The metasurface is a biperiodic array of identical meta-atoms, each of which comprises a silicon layer with a graphene patch on each of its two faces. The polarization-insensitive

Internet-based communication has become a major field, with a user base that is expanding day-by-day. The needs have overloaded the available bandwidth, and higher speed has become a mandatory requirement to satisfy the user demands and increased use of the internet. Therefore, there is a need for high-performance computers due to increasing dependence on computing technology. Optics is emerging as

Aiming to minimize the surface distortion of large-aperture laser transport mirrors in high-power laser facilities, an assembly design and mounting method are proposed for the mirror. First, a theoretical model on the mirror surface deformation is established. With a new assembly design, the mirror is fastened on its neutral plane and its optical surface distortion can be precisely compensated through

By using the orthogonality of the orbital angular momentum (OAM) beam and the characteristics of its annular intensity distribution, a method for separating the OAM beam from the Gaussian beam is proposed. This method uses a dual-area mirror in an OAM multiplexed data link. Experiments show that the topological charge of the multiplexed OAM beams can be reconfigured with the aid of a dual-area mirror

In this study, a one-way electromagnetic waveguide consisting of magneto-optical (MO) and parity-time (PT)-symmetric materials was constructed. Due to the composite boundary conditions, this waveguide simultaneously has two unidirectional dispersive curves and two different unidirectional mechanisms. One unidirectional mechanism is breaking the time-reversal symmetry of MO materials, and the other

Rapidly space-division multiplexing (SDM) techniques have drawn attention because the traditional available physical dimensions to orthogonally multiplex data have been almost exhausted. Few-mode fiber becomes a viable option to realize a high-density SDM system. Thus, we propose an air-hole assisted elliptical ring fiber. Four air-holes are introduced surrounding the elliptical ring fiber, and one

Both intensity and phase information of images have been the most important similarity measures in solving the general stereo matching problem. Intensity contains most of the imaging information of the scene/object, yet the phase information could reflect the local structure of images, which is more robust than the grayscale value. Plenty of work has been done in intensity-based or phase-based stereo

The differential phase-shift keying-based dual-hop underwater wireless optical communication-free-space optics (UWOC-FSO) convergent system is proposed for UOWSNs and Internet of Underwater Things (IoUT) applications. In the proposed system, the collected sensor data are transmitted to a decode-and-forward relay using underwater optical wireless communication links modeled as gamma–gamma distribution

To quantitatively analyze the influence of vehicle platform vibration on the vehicle laser radar (LIDAR) measurement accuracy, the modal, harmonic response, and random vibration are analyzed using finite-element software. On this basis, combined with the optical path structure of LIDAR, the deformation of mirror caused by vibration is analyzed. The results show that the maximum deflection of the laser

We report a systematic study of cuprous oxide (Cu2O) films prepared on glass substrates via radio frequency reactive magnetron sputtering at room temperature. We consider the effects of the target power and film thickness on film structures, morphologies, and optical properties. X-ray diffraction indicates significant changes from an amorphous film to a paramelaconite film and then to a cuprite film

In the last few years, interest in research and development into new ways of creating gradient index optics has increased dramatically. One approach revisited was to employ diffusion, governed by Fick’s law, to generate both axial and radial index gradients. However, Fick’s law of diffusion tends to yield index gradients that are mathematically uncommon in optical engineering and lens design. The impact

The performance of free-space optical (FSO) communication systems based on avalanche photodiodes (APDs) is investigated over the aggregated double generalized gamma (double GG) fading channels. The approximate average bit error rate (ABER) expression is theoretically derived in terms of the double GG distributions under moderate and strong turbulent atmospheric conditions considering thermal noise

Laser active imaging is widely used in many fields. The intensity image quality of laser active imaging is affected by various degradations, such as speckle effect and noise. Most existing objective image quality assessment (IQA) methods that consider only a single distorted image are not suitable for an intensity image. A multiscale full-reference intensity IQA method is presented. The proposed method

The intensity of objects in the infrared is an important quantity for a number of applications. Intensity in watts per steradian is the parameter that is used to describe either small targets or targets that are far away. Intensity is used because these cases are usually presented to a detection sensor where the object is smaller than the sensor detector angular subtense, a situation known as an “unresolved

It is critical to accurately obtain a phase position in a digital fringe projection system. Due to stray light in a complex environment, when projecting an image of a code fringe, the projected light intensity can be influenced. As a result, the intensity of fringe light captured with the camera may be defective, resulting in the decline of measurement precision. Hence, we propose a strong suppression

A scheme of parabolic pulse generation is proposed and verified by simulations and experiments. Based on a multiply operation, a parabolic pulse can be obtained by carving a triangular envelope with a triangular time window. Theoretical analysis shows that an ideal dark parabolic pulse and frequency-doubled parabolic pulse can be generated under the triangular profile with the second-order approximation

A real-time viewpoint generation-based 3D display with low crosstalk and high resolution is proposed. The proposed 3D display consists of a pattern image display (PID), a lenticular lens, and a transparent liquid crystal display (LCD) panel. For each eye of the observer, the PID can provide a pattern image with stripes that have a calculated pitch and displacement according to the eye position. The

As insulators play an important role in power transmission lines, we propose an intelligent method based on the convolution neural network (CNN) to evaluate the corona discharge of an insulator. In this method, the imaging device is a dual-spectra camera with a visible channel and an ultraviolet (UV) channel. The CNN is adopted to identify the detection distance of the insulator with the visible channel

Antireflective nanostructured surfaces (ARSS) enhance optical transmission through suppression of Fresnel reflection at boundaries between layered media. Previous studies show that random ARSS (rARSS) exhibit broadband enhancement and polarization insensitivity in transmission when applied to flat optical windows. Zinc selenide windows with rARSS treatment were fully characterized (transmittance, reflectance

Lensless microscopes are simple, portable, and cost effective compared with the sophisticated microscopes of today that require high-end objectives, lenses, and filters. We demonstrate a lensless on-chip phase microscope based on the holographic principle to image 3D nanometric depth information from transparent and weakly scattering biological samples. We characterize the microscope using standard

We present a MoS2–graphene bilayer-based high-performance refractive index surface plasmon resonance (SPR) sensor applying an angular interrogation technique. We used it for inspecting the reflected optical signal from the sensing medium. For enhancing the sensor angular sensitivity (S), signal-to-noise ratio (SNR), and quality factor (QF), we undertook some steps sequentially. First, the impact of

We propose to introduce a phase shift in each ring of the multi-stage interleavers based on add-drop resonator Mach–Zehnder interferometer to quantitatively measure the wavelength offset of each interleaver, thus a demultiplexer with uniformly segmented multi-channel output can be obtained. It is found that the additional phase of a certain interleaver is equal to the offset value of this stage plus

Our work studies the spatial distribution of ocean optical turbulence through numerical simulation. We used the ocean optical turbulence phase screen created by the ocean power spectrum to study the effect of varying the refractive index of water via a laser beam propagating through ocean optical turbulence. Because the intensity of ocean optical turbulence is much higher than that of atmospheric turbulence

We experimentally demonstrate the performance of a complex deep neural network (CDNN) equalizer in multi-band super-Nyquist carrier-less amplitude and phase (m-SCAP) modulation for underwater visible-light communications (UVLC). The in-phase and quadrature of the complex data after the match filter and down-sampling are combined as real number pairs and input to the CDNN, which outputs the real part

High explosives (HE) represent a high risk to the safety and health of the general population. Therefore, there is an ongoing demand for methods of analysis with limits of detection at trace levels for these hazardous chemicals. Since human hair is one of the main physical attributes of our bodies, the interaction of hair surfaces with HE can be of critical importance in forensic and security applications

We describe the development of a lightweight, high-resolution surveillance camera for deployment on high altitude platform systems. The instrument is designed to operate at an altitude of ∼20 km and has an expected ground resolution of better than 120 mm with an appropriate sensor. While designed specifically for imaging at visible wavelengths, it is shown that the design is capable of diffraction-limited

We present a state-of-the-art ultraviolet (UV)-based multiuser indoor communication over power-constrained discrete-time Poisson channels. To adhere to the UV exposure limit and safety, we consider a low-power transmission regime where strict peak and average transmit power constraints are imposed. These constraints are different from conventional electrical power constraints. Therefore, performance

We present the development of a multi-user cross-layer security network implemented on the optical code-division multiple access (OCDMA) with newly designed hybrid 2D-modified Walsh code (MWC) along with an algorithmic approach in cryptography domain. Minimum BER value is evaluated on the order of 10 − 50 using our designed MWC, which is comparatively lower than other existing codes. The security performance

Object tracking technology is being continually improved to ensure robust tracking performance under real conditions, such as cluttered background, fast motion, and lengthy occlusions. The performance of these video trackers depends significantly on evaluation methodologies adopted during the assessment of tracking algorithms. Most of these video trackers are evaluated using video sequences annotated

We present the results of research of autocollimating null-indicator in the angle measurement system intended for measuring angles between normals to faces of optical polygons or mirrors. The autocollimating null-indicator is considered with analog signal processing based on its digitization and center of mass estimation. We present the results of modeling and analyze the dependence of the sampling

High speed time-resolved wavefront and imaging measurements were taken synchronously in-flight through both boundary layer and shear layer environments around the Airborne Aero-Optical Laboratory for Beam Control. Instantaneous modulation transfer functions and point spread functions (PSFs), which characterize image degradation, were generated using wavefront data. Instantaneous power-in-bucket ratios

We have successfully compressed the pulse duration of an all-normal-dispersion (ANDi) Yb-fiber laser to sub-100 fs by a single-mode nonlinear fiber amplifier. Through optimizing the input power, prechirp, and the pump power of the amplifier, the pulse duration of the ANDi Yb-fiber laser is compressed to 68 fs when a 2.5-m active fiber is used, although for a 3.5-m active fiber, the pulse duration of

Photonic firewalls that can directly conduct the data discrimination and intrusion detection at the optical layer are an important security technique for optical networks. In the photonic firewall, binary sequence matching module is the core part and is implemented by multiple all-optical logic gates such as all-optical AND gate, all-optical XOR gate, etc. However, the semiconductor optical amplifier

We present an accurate laser radar receiver with a wide dynamic range intended for ranging applications based on an event-based approach, in which a receiver-time-to-digital converter is used to extract the timing information from the reflected echo. The receiver is based on LC resonance pulse shaping at the input so that the unipolar pulse detected by the avalanche photodiode is converted to a bipolar

A probabilistically shaped 9-ary carrierless amplitude and phase (CAP-9) optical modulation format based on a reverse distribution model is proposed. We experimentally demonstrate the transmission of 33.3-Gb / s PS-CAP-9 signals over 25-km standard single-mode fiber in an intensity-modulation and direct-detection system. The results indicate that the proposed scheme outperforms the conventional uniform

Because well-considered optical buffers have not been developed to date, the optical circuit switching (OCS) mechanism has been used widely for data transmission applications in existing optical network-on-chip (ONoC) devices. Unfortunately, with increasing network loads and increasing numbers of intellectual property (IP) cores, ONoCs based on the OCS mechanism are facing serious node congestion problems

Conventional methods used to inspect the molten pool surface induced by arc welding processes are based on post-welding evaluation using destructive or semi-destructive testing methods. Many attempts were performed to develop alternative and nondestructive tests. In this context, a polarimetric vision methodology is evaluated. The polarimetric parameters are measured from the thermal radiations emitted

Multimode interference (MMI)-based optical splitter is designed and experimentally demonstrated on silicon on insulator for on-chip optical interconnect. We have proposed MMI-based 1 × 2 optical 3-dB splitter having a compact footprint (2.8 × 27 μm2). The device shows low excess loss of 0.05 dB for TE mode at operating wavelength 1550 nm and <0.45 dB over broad wavelength 1430 to 1675 nm (S–C–L–U band)

We propose a mathematical model of multiple interference phenomena occurring inside the dielectric cavity of the metasurface absorber. Subsequently, it derived the expressions for electric and magnetic fields within the structure. The model enables one to mathematically interpret wave propagation, standing wave formation, and absorption in terms of electric and magnetic fields. We also discussed the

Waveform light detection and ranging detection (LiDAR) systems capture the entire backscattered signal from the interaction of the laser beam with objects located within the laser footprint. The target response (TR) is a time-dependent curve implying the geophysical attribute of the detected objects. TR restoration by removing the effect of the system waveform (SW) from the received waveform is crucial

Three-dimensional light field imaging in laparoscopic surgery is an emerging technology, which has the potential to enable three-dimensional imaging. Calibration of the three-dimensional light field endoscope (3D LFE) is essential but challenging as the disparity is much smaller than that of the conventional light field camera. The geometrical model for 3D LFE is established, and a calibration method

Due to the unique mechanical and optical characteristics, it is difficult to carry out experimental research and online measurement for large-aperture ICF frequency converters. To analyze and optimize the performance of the frequency converters under complex process loads, we present an integrated optomechanical method that correlates actual process loads with laser critical characteristics. Based

With the development of technology, the total extent of global pipeline transportation is also increased each year. Nevertheless, owing to the wide distribution of gas and oil pipelines and the complex laying environment, the traditional long-distance optical fiber pre-warning system (OFPS) has a high false alarm rate when recognizing events threatening the pipeline safety, and it is difficult to define

Efficient dielectric–plasmonic interconnect is significant in the design of future electronic–photonic integrated circuits that deal with large data transfer. We propose three designs and analysis of small-footprint couplers that are located at the interface between dielectric and plasmonic waveguides. To the best of our knowledge, our proposed couplers outperform all the works reported in the literature

A digital domain dynamic path accumulation method for a time-delay-integration (TDI) image sensor that can realize on-chip compensation for image distortion caused by sensor vibration is proposed. Through the proposed method, the exposure signals are controlled to enter the corresponding accumulator according to the vibration vector, ensuring the synchronous accumulation of different stages of pixels

Laser-based displays have attracted much attention because they are the only displays that can express the full color gamut of Ultra-High Definition Television (U-HDTV), International Telecommunication Union Radio Communication Sector Broadcasting Service (ITU-R BT).2020. We have developed 638-nm broad-area laser diode (LD) with 75-μm-wide dual emitters and achieved wall plug efficiency of over 40

Optical spatial modulation (OSM), a recent optical multiple-input multiple-output transmission scheme in wireless optical communication, has aroused great research interests. OSM scheme requires accurate channel state information (CSI) during transmitter and receiver sides, but it is difficult to accurately estimate CSI in OSM scheme. Therefore, a scheme named differential optical spatial modulation

An improved model of erbium–ytterbium codoped fiber amplifier (EYDFA) considering the effects of radiation is proposed. In this model, terms of radiation-induced losses are introduced into power propagation equations, combined with the simplified rate equations to simulate radiation effects on EYDFA performances related to space missions. A method for recovering background losses and radiation-induced

Rapid advancement in the development of hyperspectral image analysis techniques has led to specialized hyperspectral missions. It results in the bulk transmission of hyperspectral images from sensors to analysis centers and finally to data centers. Storage of these large size images is a critical issue that is handled by compression techniques. This survey focuses on different hyperspectral image compression