Optical mobile communication (OMC) provides a hopeful vision to handle with wireless communication scenarios where multiple mobile users are involved. In previous work, achievable rate analysis for broadcast OMC system with coherent transmission and detection is given. Although it was shown that OMC has superior performance compared with conventional schemes, coherent processing imposes strong challenges

We report a ReSe 2 passively mode-locked composite YVO 4 /Nd:YVO 4 laser at 1.06 μm, which can stably generate pure continuous-wave mode-locking (CWML) operation at watt-level output. ReSe 2 , as a new type of 2-D transition metal dichalcogenides (TMDs), has the features of weak-layered dependence, broadband saturable absorption, low modulation depth and saturation intensity, which is beneficial to

Cloud servers are very suitable for sharing, and storing image data, and meanwhile it is confronted with many security, and privacy problems. Optical chaos, and hardware implementation of image encryption possess distinct superiorities in secret image sharing. Hence, combining the advantages of advanced reduced instruction set computer machine (ARM)-embedded platform Exynos4412 model, together with

Monitoring the state of the optical network is a key enabler for programmability of network functions, protocols and efficient use of the spectrum. A particular challenge is to provide the SDN-EON controller with a panoramic view of the complete state of the optical spectrum. This paper describes an architecture for compact on-chip spectrometry targeting high resolution across the entire C-band to

In this study, a networked spatiotemporal chaotic map model is proposed based on the traditional coupled map lattice system. In addition, the time delay and variable topology parameters are considered to make the system more practical. The chaotic properties are analyzed using a bifurcation diagram, Lyapunov exponents, and entropies. In addition, institute of standards and technology tests are conducted

We propose and experimentally demonstrate a color-shift-keying embedded direct-current-optical-orthogonal-frequency-division-multiplexing (CSK-DCO-OFDM) scheme for the VLC systems. The proposed scheme can provide not only non-flickering aggregated optical power to reduce human health concerns, but also offers additional modulation dimension or flexibility to the CSK by including high data rate OFDM

High sensitivity, small size, light weight and low power are the most critical requirements for the lasercom terminals used in free space optical communication (FSOC) systems. Coherent receivers have an exceptionally high sensitivity but their optical complexity and power consumption are too high, especially for the space-borne lasercom terminals. Recently we propose a pseudo-single-side-band-signal

In practical, the Faraday effect-induced bias error is one of the main sources of bias error for the interferometric fiber optic gyroscope (IFOG). The Faraday effect-induced bias error impairs in the performance of IFOG. Normally, the Faraday effect-induced bias errors is hardly eliminated. To improve the performance of IFOG, the accurate model of Faraday effect-induced bias errors is necessary for

We present an EO Q-switched Tm:YAP laser constructed with a periodically poled Mg-doped congruent lithium niobate (PPMgCLN) Bragg modulator. A 2-mm-thick PPMgCLN modulator was adopted, and the internal stress generated in the electric poling process was released by annealing. The peak stress-induced refractive index variance for e-wave was deduced to be 2.29 × 10 −5 at 1064 nm. When the absorbed pump

Narrow linewidth lasers with kHz or Hz have attracted tremendous attention due to their versatile applications in optical fiber sensing and optical fiber communication fields. This is because the efficiency of these fields depends on the quality of the laser source employed. This paper proposes, simulates, and experimentally demonstrates a dual cavity fiber Bragg grating assisted feedback structure

Patterns with periodically arranged dimples are fabricated by an inexpensive soft-imprint lithography technique on a flexible transparent polymer substrate. Excellent diffraction characteristics, with highly intense and fine features, are seen from these polymer layers in transmission, even though the effective refractive index variation across their thickness is very small. The diffraction is studied

Overcoming opaque barriers beyond the penetration depth is based on light-matter interactions, with applications in biomedical optics, material science and security. In wave propagation, scattering is the amount of disorder, mostly treated as a disturbance. Scattered light variations allow overcoming opaque barriers. In order to separate turbid medium layers, absorption-based contrast is commonly used

A high-sensitive refractive index sensor is proposed and demonstrated by utilizing merging bound states in the continuum, namely a set of integer topological charges in the momentum space. Through varying cladding refractive index $n_c$ , the topological charges continuously depart from the merging state, and result in the robust and considerable high- $Q$ factors (above $7\times 10^4$ ) in a large

Terahertz wave has attracted significant attention in recent years, and terahertz devices have been applied in various fields. However, the complicated and time-consuming spectrum prediction and structure design issues have hindered the widespread application of terahertz science. In this work, we propose a new method to use neural networks to predict the reflection spectrum in the terahertz band,

Silicon nitride (SiN) optical phased arrays (OPAs) have emerged as a potential alternative to their silicon counterparts, due to their potential use in enhanced solid-state light detection and ranging. Grating antennas based on a SiN waveguide suffer from a limited beam steering efficiency, owing to the relatively lower effective refractive index of the waveguide. To mitigate this limitation, we propose

To solve problems of low positioning accuracy and long time-consuming in indoor visible light three-dimensional positioning system, a visible light three-dimensional positioning method based on the improved hybrid bat algorithm (IHBA) is proposed in this paper. Firstly, some beacon points are set at the beginning of the IHBA to reduce the number of iterations. Secondly, weight coefficient is defined

We present a novel and simple scheme for all-optical microwave photonic frequency converter, free of electrical components, based on stimulated Brillouin scattering (SBS) effect. An SBS-based frequency shifter is incorporated to generate Stokes wave whose frequency is down-shifted by ${\rm{\ }}{v_b}$ , where ${v_b}$ is defined as the Brillouin frequency shift. With a tunable optical passband filter

In this letter, we present a new real-time blind signal detection technique for indoor optical communications using a supervised learning framework in an artificial neural network (ANN). We model the optical channel as a time-varying doubly-stochastic Poisson process. To compare the performance of the proposed ANN network, we present an iterative method for joint channel estimation and symbol detection

This technical paper presents an optical camera communication system by using data as input collected from a sensor that continuously garners humidity and temperature information from the environment. A small light-emitting diode (LED) and an LED array are used as a transmitter and a low-speed rolling-shutter camera as a receiver. A modulation scheme standardized in IEEE 802.15.7, referred to as variable

Known hybrid orthogonal frequency division multiplexing-digital filter multiple access (OFDM-DFMA) PONs show promise of seamless and cost-effective convergence of optical and mobile networks for 5G and beyond. This paper reports, for the first time, a new hybrid OFDM-DFMA PON based on intensity modulation and direct detection (IMDD), obtained by modifying digital signal processing (DSP) algorithms

The potential of ultraviolet (UV) AlGaN quantum well (QW) light-emitting diodes (LEDs) is stunted due to the lack of efficient p-type doping for this ultra wide bandgap material. In this work, a novel device - UV electrostatic field effect LED (EFELED) is demonstrated to address this issue by significantly improving hole injection into the QW active region which leads to a relative increase of external

All-perovskite tandem solar cells have great potential to realize the efficiency beyond the Shockley–Queisser efficiency limitation of single junction solar cells. Here we investigate the photon redistribution effect induced by introduction of the optical coupling layer in two terminal (2 T) tandem solar cells. In this work, it is shown that the introduction of the optical coupling layer could not

In this work, we modeled a novel approach to enhance surface-enhanced Raman scattering (SERS) signals using principal component analysis (PCA) as a machine learning approach. Zinc oxide nanoarrays (ZnO-NAs) were synthesized using a hydrothermal method followed by zinc oxide nucleation on ITO glass substrates via an oxidation furnace at 500 °C. The surface morphology was improved by short rapid thermal

We present a novel instrument for fast-gated operation of a 50 μm CMOS SPAD (Complementary Metal-Oxide-Semiconductor Single-Photon Avalanche Diode), driven by an integrated fast-gated active quenching circuit with transition times faster than 300 ps (20–80%). The instrument is based on a custom system-in-package where the SPAD and its driving electronics are housed in a TO-8 package. The detector can

Sensors with single resonant mode often produce false positive when detecting the composite vibrational fingerprints of molecules in the terahertz (THz) range. In this study, a multi-resonant plasmonic structure, consisting of periodic graphene split ring resonator (SRR) arrays, is proposed for THz sensing. The effective detection of ultrathin (0.1 μ m) lactose layer is given as an example to demonstrate

The double phase method is an efficient way to generate phase-only holograms with high reconstruction quality due to no addition of a random phase. However, it cannot directly encode the Fourier spectrum because of the limited gray modulation range of spatial light modulator, and quantization error. This shortage restricts the application of the double phase in the phase-only Fourier hologram, and

We propose and experimentally demonstrate a novel and simple approach to identifying both the direction and value of Doppler frequency shift (DFS) in this paper. A pair of phase modulators, as well as a dispersion medium in between them, are employed in the approach. The different dispersion-induced phase shifts of the upper and lower sidebands after passing the dispersion medium can be used to determine

In this paper, we present experimentally an erbium-doped fiber (EDF) laser system to accomplish the single-longitudinal-mode (SLM) and wavelength-upconverted output by using nonlinear effect. To accomplish the SLM output, a short length of unpumped EDF saturable absorber (SA) is applied inside the EDF laser cavity for filtering densely multi-mode noise. In accordance with the designed EDF laser system

High-order mode fiber lasers are gathering the rising attentions from fundamental researches to practical applications due to their distinctive spatial and temporal properties. Here, we demonstrate a carbon nanotube mode-locked two-mode fiber laser and investigate the formation and evolution process of the soliton based on the time-stretch dispersive Fourier transform method. Stable single pulse and

Herein, a refractive-index sensor is theoretically proposed, which comprises metal-insulator-metal waveguide and single rectangle cavity without a long side (RCWALS). The propagation characteristics were analyzed by finite element method. Compared with the contrastive structure, the designed single RCWALS structure has better transmission spectra and stronger resonance and supports Fano resonance.

A new efficient boundary condition of finite element method (FEM) by using propagation operator is proposed. In this method, input, and output ports are terminated on their own boundaries instead of using perfectly matched layer (PML) which requires expanding the computational window. Moreover, this boundary condition can consider all modes including radiation modes without mode expansion. The propagation

In this article, the numerical simulations and experimental investigations on the evolution of soliton rain in Tm-doped fiber laser were carried out, based on the nonlinear polarization rotation (NPR) technique. By carefully adjusting the polarization controller (PC) in the cavity, the soliton rain phenomenon was observed, in which the pulse train length of a drifting solitons was about 0.36 μs, 0

A distributed birefringence measurement of a polarization-maintaining fiber (PMF) can be realized by using a Brillouin dynamic grating (BDG). However, the pump depletion decreases the intensity of the BDG along the PMF and limits the measurement range to a few hundred meters. We demonstrate a distributed birefringence measurement of the PMF with an extended range to 3030 m based on an enhanced BDG

An enhanced distributed optical fiber sensor based on broadband ultra-weak fiber Bragg grating array (UWFBG) for dynamic strain measurement with large temperature tolerance range was proposed and experimentally demonstrated. The reflectivity of UWFBG is about −50 dB, and the intensity of the reflected signal is 17 dB higher than the Rayleigh back-scattering. Using an unbalanced Michelson interferometer

This paper deals with the optimization of photonic structures, specifically waveguide couplers between a continuous waveguide (CWG) and a periodically segmented waveguide (PSW). For this purpose, a numerical technique called finite element method (FEM) is used in conjunction with an adapted optimization technique called Scatter Search (SS). In this work the possibilities of finding high coupling efficiencies

Free Space Optical (FSO) communication links are although extremely vulnerable to atmospheric adversities, multi-hop relay transmission can however, significantly improve the link performance and reliability. This paper proposes 120 Gbps DP-16 QAM modulated multi-hop serial FSO link with coherent reception for delivering medical consultation services in remote and isolated locations. Considering the

Our goal is to develop an energy-autonomous solar cell receiver that can be integrated with a variety of smart devices to implement the Internet of Things in next-generation applications. This paper details efforts to develop such a prototype, called AquaE-lite. Owing to the capability of detecting low-intensity optical signals, 20-m and 30-m long-distance lighting and optical wireless communication

Traditionally, optical vortices (OVs) were generated with diffractive optical elements (DOEs) such as spiral phase plate (SPP), fork grating, spatial light modulator (SLM), and liquid crystal display (LCD). Here, a method was proposed for generating OVs by employing all-dielectric polarization-insensitive metasurfaces with cylinder arrays, which have high transmission efficiency. The polarization insensitivity

A novel weak one-dimensional field confinement silica waveguide (WCSW) with a large horizontal and vertical aspect ratio and low refractive index difference is proposed and fabricated via sol-gel technique. This new type of waveguide exhibits properties of high lithography tolerance, low polarization dependence, low propagation loss and low coupling loss with a single-mode fiber. More importantly,

The accurate screening of otitis media (OM) lies in clarifying the numerous confounding and quantitative factors that are discovered during primary inspections. Increased awareness about bacterial biofilms and inflammation has allowed researchers to develop a better understanding of the bacterial infections that occur in the middle ear. In this study, four live guinea pigs were inoculated with Streptococcus

In this paper, we propose an advanced three-dimensional visualization method for an integral imaging microscope system to simultaneously improve the resolution and quality of the reconstructed image. The main advance of the proposed method is that it generates a high-quality three-dimensional model without limitation of resolution by combining the high-resolution two-dimensional color image with depth

Due to weather conditions, brightness conditions, capture equipment and other factors, leads to video unclear or even abnormally confused, which is not conducive to monitoring, and can not meet the needs of applications. Based on the actual data of night video surveillance, this paper proposes a new low illumination video image enhancement algorithm, which overcomes the existing problems. We analyze

Superconducting series nanowire single-photon detectors (SNDs) have been used for resolving photon numbers. But it can also exhibit a higher counting rate than a single superconducting nanowire single-photon detector (SNSPD), because the serial architecture allows multiple detectors working in parallel and the inductance of each pixel is reduced. In this paper, we found each pixel of the SND could

We propose a plasmonic signal copier (PSC) composed of a gapped surface plasmon polariton waveguide (SPPW) and an optical waveguide laid across the gap. The interaction between an SPP and an optical signal around the gap edge is demonstrated experimentally and numerically with polarizations of the incident optical wave. A plasmonic signal is invertedly copied from a TE-polarized optical signal incident

We demonstrate automated adaptation, and stabilization of a silicon photonic wavelength-division multiplexing (WDM), polarization-independent receiver. A two-channel, tunable WDM polarization-independent receiver is designed, and used to demonstrate automated WDM polarization control. Using a control algorithm based on Barzilai, and Borwein's two-point step size gradient descent method, we realize

Fluctuation of the optical power incident on a photodiode will cause phase variation of the electrical signal. This phenomenon is known as amplitude-to-phase (AM-to-PM) conversion. The effects of bias voltage and test frequency on AM-to-PM conversion are described systematically in this paper. A larger null point of AM-to-PM coefficient and smaller phase variation have been observed when bias voltage

A novel method for receiving weak microwave photonics signals based on a micro-ring resonator is proposed. This approach uses the nonlinear interaction of a microwave and an optical pump to generate an up-conversion signal to achieve the signal reception. The minimum detectable power of this method reaches −89.79 dBm, which is suitable for the detection of weak signals. The power conversion efficiency

The large volume and weak environmental adaptability of fiber optical frequency combs (OFCs) have become the main obstacles for their applications in various fields. To address these issues, in this study, we present a compact, low-cost f -to-2 f interferometer and fiber actuator with a large tuning range and a high control bandwidth for a 200-MHz OFC that is based on a 1.5-μm all-polarization-maintaining

Despite the fact that underwater optical wireless communication (UOWC) systems are able to provide high-data rate links with high security, the performance of these systems presents several limitations related to the maximum achievable distance due to attenuation, and scattering effects. Hence, quantifying the signal attenuation, and the time-dispersion produced by such effects represents a crucial

We discuss an optical ray-tracing approach to minimizing path-loss in a variable link length indoor blue laser down-converted white light visible light communication (VLC) system. For a given link length, minimum path-loss is achieved by finding optimum positions of transmitter and receiver lenses relative to phosphor and detector respectively such that collection efficiency is maximized. The designed

Chest X-ray (CXR) images are usually used to identify the causes of patients’ symptoms, including the classes of lung or heart disorders. In visualization examination, CXR imaging in anterior–posterior (A–P) views is a preliminary screening method used by clinicians or radiologists to diagnose possible lung abnormalities, such as pneumothorax (Pt), emphysema (E), infiltration (In), lung cancer (M)

A novel design of a tunable optical switch based on epsilon-near-zero (ENZ) metasurface is proposed, which can work as an electro-optical or an all-optical switch, and be tuned by gate-voltages, incident angles, and intensity of pump light. The result shows that the coupling of the ENZ mode and plasmon resonance lead to an obvious Rabi splitting which can be observed in the transmission spectrum. Numerical

We propose a passive detection and tracking methodology for CamCom receivers in intelligent transport systems. The implemented architecture maximizes the data rate and can maintain a BER of 1.9 × 10 −4 while passively detecting and tracking the moving transmitter undergoing worst-case road vibration of 30.6 mm/s. The proposed methodology is also independent of the size and shape of the transmitter

By exploiting the electro-absorption characteristic of graphene, we proposed and theoretically demonstrated an electro-absorption optical modulator (EOM) based on the graphene-buried polymer waveguides. By burying the graphene layers inside the polymer waveguide, acquiring a strong graphene-light interaction when the graphene layers buried in the center of core, which bring about an important change

We studied the relationship between the absorption layer length and the performance of Ge-on-Si microring resonator photodetectors. The principle of optimizing the absorption layer length based on the light field distribution was proposed. In the Ge-on-Si photodetectors, the transmission light field is alternately distributed among the germanium absorption layer and the silicon waveguide layer, and

High-finesse fiber Bragg gratings (FBGs) Fabry-Perot interferometers (FPIs) have shown great promise as sensitive ultrasonic sensors. However, the fabrication process of the sensors usually introduces birefringence to the fiber, which makes the sensor operation sensitive to the polarization of the probe laser. Here, we theoretically study the effect of laser polarization on the sensitivity of the sensor

We present experiments and numerical simulations of optical frequency combs generated by gain-switching a single mode laser diode when subject to optical injection. Our analysis focuses on the combs with a frequency separation $f_R$ in the GHz range. We present experimental maps in the parameter space spanned by the detuning and the strength of the optical injection that identify the boundaries between

Functional near-infrared spectroscopy (fNIRS) is widely used in brain science. The sensitivity and signal-to-noise ratio (SNR) are core parameters during the measurement. However, previous studies have not systematically analyzed the parameters in whole-brain measurements which limits its further improvement. In this paper, a noise model was established, including electronic noise, shot noise and speckle

Multi-fringe projection profilometry, such as the widely used phase-shifting and temporal phase unwrapping algorithms, can achieve high accuracy and robustness in three-dimensional shape reconstruction of static objects. However, the motion of the objects will introduce errors. This paper proposes a new method to reconstruct 3D shape of rigid moving objects on an automated transmission line. First

Display luminance is one of the most important factors that influence not only display performance but also visual discomfort greatly. To investigate the influence of display luminance and image content on visual discomfort, the haemodynamic response and subjective perception were recorded respectively when participants watched different visual stimuli. Different white levels (WLs) of display and images