High-density coherent fiber bundles, mainly used for high-resolution fiberscopes, consist of non-circular cores and have various optical noises such as auto-fluorescence, crosstalk, and honeycomb artifacts that may require excessive image processing. Binarization was applied to post-image processing to eliminate a calibration used as pre-image processing for traditional fiberscope image reconstruction

An efficient scheme is proposed for implementing fast population transfer in a superconducting qutrit via shortcut to adiabaticity (STA) with optimized drivings. An artificial atom of Cooper-pair box, having sufficient level anharmonicity, resonantly interacts with two classical microwave drivings. At two-photon resonance, the dynamical behavior of the qutrit can be described by a two-state system

A phase differential heterodyne interferometer for simultaneous measurement of straightness error and displacement is proposed. In this interferometer, a modified mobile sensor composed of a Wollaston prism and a semi-reflective plane mirror is adopted to obtain the straightness error and displacement information simultaneously. A phase differential measurement is utilized to obtain phase differential

We demonstrate a widely tunable InGaAs quantum-wells (QWs) distributed Bragg reflector (DBR) laser, in which the DBR section was realized by using butt-jointed InGaAsP (λ=1.46μm) material. In the device process, we explored an optimal chemical etchant applied in the butt-jointed active–passive integration technology. A wide tuning range of 10.7 nm with 19 consecutive channels is obtained with a single

Silver meso-particles (SMPs) were successfully synthesized by a simple chemical method in the presence of L-ascorbic acid reducing agent and silver ions precursor in AgNO 3. Silver meso-structures of different topographies have been synthesized by varying the concentration of the reactants such as the L-AA concentration or the Ag+ ions concentration as well as by varying the temperature reaction. The

In this paper, we present the generation of a CNOT gate between two atoms in a cavity based on transitionless quantum driving. Compared to some previous schemes, the proposed scheme for generating a CNOT gate significantly shortens the duration time. Besides, the scheme is insensitive to the fluctuation of evolution time and coupling coefficient. Also, the influences of atomic spontaneous emission

In this paper, the impact of in-(I) phase/quadrature-(Q) phase imbalance (IQI) in mixed radio frequency/free space optical (RF/FSO) cooperative relaying systems is studied. The RF link has been assumed to undergo Nakagami-m distributed fading, while the FSO link is under the influence of atmospheric turbulence modeled by the Malaga irradiance model with pointing errors. The FSO model accounts for both

The radiative cooling technology is a method of directly transmitting radiative energy to the cold sink of outer space through the existing atmospheric transparent window of 8-13 μm. Therefore, it is necessary to find a selective emitter that can match the infrared atmospheric window. Here, we combine the selective emitter with the inverse design of the direct binary search (DBS) algorithm numerically

It is shown that, when a high-power laser beam propagates from the ground through the atmosphere to space orbits, there is an optimal beam power that maximizes the target intensity due to self-focusing effect in the atmosphere, even if the atmospheric extinction exists. The B integral is an important parameter to describe self-focusing effect quantitatively. It is found that the value of B integral

This paper reports the whispering gallery mode (WGM) splitting behavior as-observed between pairs of size-matched microspheres with tight-binding positions. Dye-doped microspheres were excited by pulsed lasers in order that the WGM laser spectra could be monitored. Via analysis of experimental results, we investigated the effects of spacing between two coupled microspheres on coupling strength, and

Terahertz Kerr effect technology, as a novel tool, is expected to study the low-frequency molecular dynamics of liquids since it can directly distinguish the time-resolved anisotropy information on the sub-picosecond scale. Here, this technology is used to measure a variety of aqueous salt solutions and observe the effects of different anions and cations on the structure and dynamics of water network

We design and simulate a hollow AsSe2-As2S5 microstructured fiber surrounded by air holes with nearly-zero flattened all-normal dispersion profile. Simulation results show that the coherent first-order orbital angular momentum (OAM1,1) supercontinuum (SC) spectrum extending from 1.3 to 11 μm at −40 dB level, which can be achieved by pumping a chirp-free hyperbolic secant pulse with 100 fs pulse duration

We report a rotating optical focal field generated by inversely focusing the radiation pattern from a turnstile antenna under a 4Pi focusing system. The turnstile antenna, composed of two mutually perpendicular short dipoles with a quadrature phase offset, is employed to find the required illumination at the pupil plane for creating the rotating field by using a time-reversal holographic methodology

In this study, a novel adaptive infrared (IR) camouflage film based on one-dimensional (1D) quasi-photonic crystal (PC) with phase-change material Ge2Sb2Te5 (GST), is theoretically demonstrated. The designed film shows high emissivity state at low temperature and low emissivity state at high temperature, via the transition between amorphous and crystalline phase of GST. Moreover, the quasi-PC structure

Small changes in mirror displacement cause variations in the reflection pattern and corresponding optical path length in a multi-pass absorption cell. Herein, we propose a path length calibration-free laser absorption spectrometer based on a frequency modulated continuous wave (FMCW) ranging system. The absorption coefficient of atmospheric oxygen and the optical path length in a multi-pass absorption

Bending losses of sharply bent optical nanofibers or nanowires coupling with Au nanoparticles (Au NPs) are investigated using a finite-difference time-domain (FDTD) method. Relying on the ultra-tight optical confinement of the Au NPs, bending losses of the sharply bent optical nanofibers or nanowires can be effectively reduced by attaching Au NPs to the inner edge of the bent nanofibers or nanowires

Over the last years, LiNbO3 on insulator (LNOI) has emerged as one of the most important platforms for integrated photonic applications because of its large refractive index contrast, outstanding electro-optical and nonlinear optical properties. Rib-loaded waveguide technology is an efficient approach to avoid high surface and sidewall roughness and to relax the difficulty in construction of sub-wavelength

In this study, a novel tubular hollow-core fiber design with extended cladding structures aiming low transmission losses and dominant single-mode guidance in the infrared region is proposed. The fiber parameters are optimized to achieve low-loss operation at the target wavelength of 2μm, at which the emission spectrum of thulium-doped fiber lasers are centered. The confinement loss of the fundamental

In this paper, a hot-wire flowmeter based on the Extrinsic Fabry–Pérot Interferometer cascaded with a Fiber Bragg Grating (FBG-EFPI) is presented. The flowmeter measured the flow velocity by measuring the temperature variation based on the hot-wire effect. The FBG-EFPI sensor spectrum has a high peak slope (169.47 dB/nm), which makes it excellent for measuring temperature. The detection range of the

A real-time displacement reconstruction technique based on a phase retardation method is proposed. By introducing a waveplate and a polarization beam splitter into the external cavity, two self-mixing signals with a phase shift of π∕2 can be obtained. Then the displacement of the external object can be reconstructed by a quadrature demodulation algorithm, which significantly simplifies the data processing

We propose a super-angular aperture scheme instead of the circular aperture scheme for AOTF spectral imager to increase radiation flux of acousto-optic tunable filter (AOTF). At the same time, we quantitatively calculate the radiation flux variation caused by the super angular aperture scheme and the AOTF element response at oblique incidence. We analyze the system response of the two optical schemes

Near-field scanning optical microscopy (NSOM) is a promising technique to perform nanoscale fluorescence measurements with a nano-sized near-field-light-source. However, much like a conventional confocal measurement, it requires illuminating the sample with the focus spot of the propagating light even when the fluorescence signal of interest is generated only from a nano-sized area of the sample, causing

The expressions for the wave and the phase structure functions of a plane wave and a spherical wave propagating in the natural water turbulence characterized by the recently developed spatial power spectrum (Yao et al., 2020) are evaluated in general and in the limits of large and small separations. The spatial coherence radius for both plane and spherical waves is then deduced. The angle-of-arrival

The bimodal resonance phenomena in photonic structure have received particular attention due to their intriguing optical properties and numerous potential applications. In this work, we investigated the mode transformation behaviors of the guided modes in an integrated bimodal resonance structure consisting of a single groove on the surface of an abruptly ended slab waveguide. Numerical simulations

The measurement, two-dimensional modulation, and even three-dimensional modulation are three essential components in light field modulation. In this work, we propose a method that can measure and shape the circular Airy vortex (CAV) simultaneously by using the cross-phase for the first time. Firstly, we offer a way to measure the topological charges of CAVs with the low-order cross-phase in the autofocusing

A terahertz photo-thermoelectric (PTE) detector is proposed by integrating the metamaterial absorber with a metal thermocouple. The incident terahertz wave that is absorbed by the metamaterial absorber changes into heat, then the heat changes into electricity by using the metal thermocouple. The absorption performances, photo-thermal, and PTE conversion characteristics are investigated by the full

Based on the germanium-on-insulator (GeOI) platform, we numerically demonstrate a photonic polarization rotator (PR) operating in the 2 μm waveband. Utilizing the partial-height etching to break the symmetry of germanium waveguide cross section, the proposed PR realizes a 90° polarization rotation between the fundamental transverse electric (TE) and magnetic (TM) modes. The device footprint occupies

A compact, low-loss, simply prepared all-fiber phase modulator based on the plasmonic absorption of gold nanoparticles decorated on the surface of non-adiabatic microfiber was demonstrated By applying 808 nm pump laser of different powers to the phase modulator, the effective refractive index changes resulting in phase shift of the interference spectrum at 1550 nm. The proposed device can also be utilized

We demonstrated all polarization-maintaining fiber (PMF) lasers which could offer selective transverse mode emission by polarization rotation technique (PRT). Offset and cross splicing between PMF sections was used to generate higher order mode and to yield a birefringence induced mode filter. PRT was used to select the output beam profile. Both linear cavity and ring cavity were explored. Experimentally

A transmission reflection selective ultranarrow-band metamaterial filter based on electromagnetically induced transparency (EIT) operating at visible wavelengths is demonstrated theoretically and experimentally. The theoretical work starts with the design of an EIT structure with two separate resonance parts. Then the two resonance parts are connected and the hardness of the metamaterial filter is

It remains a tough task for designing a microscopy system to approach the diffraction limit over a wide field of view due to its restricted space bandwidth product (SBP). Fourier ptychographic microscopy (FPM) has been developed to broaden the SBP of a conventional microscope platform without major hardware modifications. In this paper, we propose a novel FPM system based on the phase-coded speckle

A highly sensitive optical fiber temperature sensor with a polydimethylsiloxane (PDMS)- coated tapered dispersion compensation fiber (DCF) structure is proposed, the structure consists of single mode fiber (SMF)- tapered dispersion compensation-single mode fiber (STDS). The sensing principle is based on the interference between DCF and SMF due to a large core diameter mismatch. The interference of

In this paper, a few mode fiber temperature sensor based on vernier effect is proposed. The sensor consists of two cascaded microcavities and realizes temperature sensing based on vernier effect. The single mode fiber(SMF) and few mode fiber(FMF) are fixed by a capillary glass tube to form an air reference microcavity. The end of the FMF is dipped with an appropriate amount of polydimethylsiloxane(PDMS)

With the development of nanoscale transducers, surface acoustic wave (SAW) with frequencies above 10 GHz can now be excited on the optical waveguides. However, the fundamental mode is very difficult to be excited for SAW at ultrahigh frequencies. Moreover, as the wavelength of SAW is reduced to below the optical wavelength, the acoustic field across the optical waveguide can no longer be approximated

Ultraviolet lenses are core components of surveillance cameras, lithography machines and UV microscopes. Traditional refractive UV lenses are bulky, expensive and easy to aging, which hinders their applications in miniaturized and integrated photonic devices. In this paper, we proposed a polarization independent, broadband achromatic metalens that consists of arrays of silicon nitride nanopillars on

The paper proposes to unify the two-photon laser and induced cooperative scattering Raman lasing in which the flying ensemble of two-level excited radiators are coupled with the bimodal cavity field in nonlinear two-photon and scattering interactions. It discusses the situation in which the induced two-quantum lasing takes place together with the cooperative scattering conversion of photons between

A physical-layer network coding (PNC) based inter-ONU-communication (IOC) scheme is proposed for next generation high-speed PONs which apply four-level pulse amplitude modulation (PAM4). A 25 Gb/s full-duplex and private communication is demonstrated.

An optical fiber current sensor based on helical long-period fiber grating (HLPG) inscribed in polarization-maintaining fiber (PMF) by CO2 laser has been proposed. The PMF-HLPG is put into the solenoids with a direct current (DC) current source, and the value of applied current can be measured by monitoring the rotation angle of the input elliptical polarized light due to the changes of the magnetic

The use of GaN photoconductive semiconductor switches (PCSSs) is plugged by the high local electric field at the electrode edges and the low on-state current in the sub-bandgap triggering mode. Therefore, a new high-power semi-insulating GaN PCSS structure, which is a quantum well coupled with a trench PCSS (QWTPCSS), is presented. The trench changes the electric field distribution. In the off state

Phase-only information derived using a double random-phase encryption (DRPE) algorithm is not visually recognizable but can be authenticated using a nonlinear cross-correlation method. This can be considered to enhance DRPE security (which is vulnerable to a chosen-plaintext attack). Here, we show that phase-only images derived using the DRPE method remains vulnerable to such an attack; the at-risk

When a parallel light beam illuminates a curved air–liquid interface, a group of self-interference fringes appears in the reflection field in the region near the critical point. A model describing the interface height and slope dependences on the fringe phase supports this observation. The fringe phase function is determined by the fringe image. The height, slope, and curvature of the interface curved

This paper investigates the hybrid free-space optical (FSO)/radio-frequency (RF) communication system under the influence of non-cooperative target (NCT) which includes eavesdropping the legitimate transmitters and jamming the legitimate receivers. The FSO link and RF link are modeled by Málaga(M) distribution and Nakagami-m distribution respectively. Both yield excellent fit experimental data as unified

Southern Spectroscopic Survey Telescope (SSST) is a wide-field spectroscopic survey telescope that China plans to build in Chile in the next few years. As an instrument for astronomical spectroscopic survey, the multi-object and fiber-fed spectrograph (MOFFS) is one of the most important scientific instruments for SSST. In this paper, we present a recommended optical design for the MOFFS system based

Most of the PAM4 receivers eliminate the linear and nonlinear distortion by equalization and use independent symbols for decision. In this work, to remove the residual correlation between adjacent symbols after equalization, the enhanced hard decision (HD) based on multi-dimensional basis expansion is theoretically investigated and experimentally demonstrated for a 10-GHz directly modulated laser (DML)

Photoacoustic (PA) cell is an important component for PA spectroscopic trace gas measurement. However, its high responsivity towards light absorption in trace gases can be compromised to the background baseline generated from optical windows of the cell. In this research, a 2-D physical model considers double effects (thermoelasticity and thermoacoustics) was proposed to reveal the generation mechanism

In this work, a magnetic sensing scheme based on whispering gallery mode (WGM) hollow microbubble resonator (HMR) filled with magnetic fluid (MF) is proposed. The HMR is made by the pressure-assisted arc discharge method on the microcapillary. WGM is excited by evanescent fields in HMR. The quality factor of resonator is 4.02×106. Then, the influence of the wall thickness of HMR and the concentration

In order to reduce the complexity of the light-emitting diodes (LEDs) selection procedure in generalized spatial modulation (GSM) assisted indoor visible light communication (VLC) system, a support vector machine (SVM) aided low complexity and high efficiency machine learning LEDs selection algorithm is proposed for the considered GSM–VLC system. By modeling the LEDs selection problem in indoor GSM–VLC

We successfully constructed a pulse laser whose fundamental repetition rate is 2.6-GHz in Q-switched mode-lock oscillation. To the best of our knowledge, this is the highest repetition rate among silica glass fiber lasers. The laser cavity was constructed by a 40-mm-long Nd3+-doped single-mode silica glass fiber (Nd-SMF) and a SESAM as a saturable absorber. The core glass of the Nd-SMF was fabricated

Nanocavity mediated directional coupler in plasmonics waveguides is proposed and numerically investigated. Perfect directionality with enhanced light intensity coupled to the desired direction is obtained through the chiral eigenmode of the nanocavity excited by an elliptically polarized dipole. The directionality is robust to the position and polarization of the dipole. Furthermore, both circular

We present to use the squeezed light and the thermal effect to induce the one-way steering of magnon modes from two separated yttrium–iron–garnet spheres respectively placed in two microwave cavities. Based on the squeezed-reservoir engineering, the reduced master equation of magnon modes is derived by adiabatically eliminating the variables of cavity modes in the bad-cavity limit. Our results reveal

A compact all-optical tunable fiber filter based on a few-mode optical fiber modal interferometer coated with graphene epoxy resin composite material is proposed and experimentally demonstrated. The interferometer is constructed with a 2-cm FMF connected to two single mode fibers. After coating the graphene epoxy resin composite material on the outside of the interferometer, it shows the all-optical

A novel and simple microfabrication method for in-line micro-cavity based fiber Mach–Zehnder interferometers (FMZIs) is proposed and demonstrated by nanosecond (ns) pulsed fibers lasers for the first time. Instead of using high-end femtosecond laser for the fabrication process, only conventional ns-pulsed fiber lasers of modest optical powers are required in our approach. Such fabricated fiber MZ interferometer

We explore the role of quantum fluctuations in the strong-coupling limit of the dissipative Jaynes–Cummings oscillator driven on resonance. For weak excitation, we derive analytical expressions for the spectrum and the intensity correlation function for the photons scattered by the two-state atom coupled to the coherently driven cavity mode. We do so by writing down a birth–death process adding the

An underwater femtosecond laser layered ring trepanning (FLLRT) technology is reported in this paper. The FLLRT experiments are performed in silicon carbide (SiC) ceramic sheets in air and water. The effects of water immersion and laser pulse repetition rate on laser trepanning quality and hole generation characteristics are demonstrated by altering the laser pulse repetition rate. The underwater FLLRT

In this paper, a reactive defragmentation rerouting and spectrum assignment (RDRSA) strategy when existing connection requests terminated and network resources released is presented. In RDRSA with spectrum conversion (SC), the existing connections are re-established to new route or reassigned to new frequency slots. Defragmentation has three advantages over the conventional RSA: (1) at the time of

An estimation method for complex index of refraction based on polarized reflection measurement under active illumination is presented. In this method the ratio of pBRDF (polarized Bidirectional Reflection Distribution Function) matrix elements f10/f11 given by active polarized reflection measurement is chosen as the new index for least squares approximation to estimate the complex indexofrefraction

Integrated photonic circuits are an integral part of all-optical and on-chip quantum information processing and quantum computer. Deterministically integrated single-photon sources in nanoplasmonic circuits lead to densely packed scalable quantum logic circuits operating beyond the diffraction limit. Here, we report the coupling efficiency of single-photon sources to the plasmonic waveguide, characteristic

Optical fiber sensing technologies play an important role in the optimization of chemical material production processes and curing monitoring in new materials development. A novel fiber-integrated Fabry–Perot interferometer sensor is proposed and demonstrated in this work. For the first time to our knowledge, this development realizes the real-time monitoring of UV curing. The sensor was composed of

In this paper, a wide-spectrum orbital angular momentum (OAM) based free space communication system is experimentally demonstrated. The wide-spectrum laser can be generated using narrow-linewidth pulses to pump nonlinear fiber and the OAM beam can be generated with spatial light modulator (SLM). In the experiment, a controllable atmospheric turbulence simulation device was used to ensure a unified

In this paper, we propose a nonlinear interferometer based on two-port feedback nondegenerate optical parametric amplification (NITFPA), which employs two linear beam splitters to feed the two output beams of a nondegenerate optical parametric amplifier back to its input ports. By comparing the NITFPA with the SU(1,1) interferometer (SUI), which is another typical nonlinear interferometer, we demonstrate