Miniaturization of imaging systems has become an important requirement for studying the brains of freely behaving animals (mice, birds, etc.). The author presents a 1-photon miniscope device with significant mechanical (weight: 1.3g, small size: 10mm $\times17$ mm $\times12$ mm) and optical (lateral resolution: 1 $\mu \text{m}$ , magnification: 12.5, etc.) advantages compared to existing systems. This

The effect of drawing conditions on the optical properties of the bismuth-doped high-germania-glass core fibers has been studied. It was found that the gain characteristics of these fibers become better with the increase of the drawing speed from 10 to 100 m/min. The small-signal absorption spectra of the Bi-doped fibers obtained at drawing speeds lower than 1 m/min are characterized by a high level

A cascaded Mach-Zehnder interferometer based filter for coarse wavelength (de)multiplexing (CWDM) at the O-band is fabricated and tested on a silicon nitride on SOI platform. We characterize the chip-to-chip performance variability of the filter devices on a wafer. Using the optical measurement data, we apply Bayesian inference methods to estimate the waveguide geometery parameters and also quantify

This letter presents the design and measurements of a monolithically integrated photonic receiver manufactured in 0.25 $\mu \text{m}$ SiGe BiCMOS electro-photonic technology. The receiver consists of an on-chip germanium photodiode directly connected to the transimpedance amplifier (TIA). An on-chip, low-noise feedback loop compensates the dc photocurrent. The circuit provides a maximum bandwidth of

In this letter, we experimentally demonstrate various low-amplitude sub-pulses releasing from the rectangular-shaped noise-like pulses (NLPs) in a passively mode-locked fiber laser. Via incorporating a several hundred meters highly nonlinear fiber (HNLF) in the cavity, a series of continuous wave (CW) components are observed in the output optical spectrum, and sub-pulses formation results from the

We demonstrate an innovative approach to fabricating scalable VCSEL arrays for high-pulsed-power applications. The VCSEL arrays consist of tightly-packed, small-diameter mesas that are planarized and passivated with SU-8 resin, and connected by a large-area top transparent electrode made of indium tin oxide. Peak pulsed output power exceeding 100 kW/cm 2 of active area was achieved in arrays with very

A narrowband retroreflection is demonstrated by using a cavity-resonator-integrated guided-mode resonance filter (CRIGF) integrated on a high-reflection substrate for an oblique incidence. A CRIGF consists of a thin-film waveguide and three parts of surface-relief gratings. The middle part of the grating acts as a grating coupler, and both side parts act as distributed Bragg reflectors constructing

The unique and random physical-layer properties of optical fiber channels have been exploited for a simple and cost-effective secure key generation and distribution (SKGD). However, state-of-the-art SKGD approaches focused mainly on initial key extraction, while the post-processing protocol has to be explored to guarantee error-free operation, effective key generation rate (KGR) and high key secrecy

We experimentally demonstrate a simultaneous generation of independent 10-Gbit/s wired on/off keying (OOK) signal and 20-Gbit/s wireless quadrature phase shift keying (QPSK) signal by using a dual-polarization Mach–Zehnder modulator (DP-MZM) in a millimeter-wave-band radio-over-fiber system at 30 GHz. The polarization directions of two signals are orthogonal, so there is not any interference between

The nonlinear optoelectronic (NLOE) filter represents a novel class of filters whose filtering operation is based a signal reaching a specific amplitude rather than falling within a specific range of frequencies. This amplitude filtering aspect carries with it a stringent amplitude stability requirement where the input signal must be precisely maintained at a specific level for the signal to be rejected

Quantum optics experiments frequently require the separation of single-photon-level signals from strong classical fields. In circumstances in which the signals are spectrally close, and one cannot make use of relatively simple separation methods based around differences in polarization state, optical mode, or beam direction, it is necessary to exploit the frequency difference itself as the means for

We design and experimentally demonstrate a dual-mode 3 dB power splitter based on the self-imaging effect in a taper-assisted multimode interference (MMI) coupler. The quality reduction of the two mirrored half-power images of the input field due to accumulated high-order eigenmodes phase error will degrade the performance of dual-mode power splitter. We propose an eigenmode-selective-excitation method

We evaluate the effects of the external optical feedback on the on-off keying (OOK) and four-level pulse amplitude modulation (PAM4) signals in the single-mode fiber (SMF) link implemented by using a commercial 10G-class 1.55- $\mu \text{m}$ vertical-cavity surface-emitting laser (VCSEL). The results show that the PAM4 signal is much more sensitive to the external optical feedback than the OOK signal

In this letter, high-performance 4H-SiC ultraviolet (UV) single-photon avalanche diodes (SPADs) with a large diameter of $300~\mu \text{m}$ were designed and fabricated. For the first time, the influence of an incident UV photon flux on the single-photon-counting performance of 4H-SiC SPADs is investigated. With the UV photon flux increasing from ~100 photons/ $\text{s}\cdot \mu \text{m}^{2}$ to $2

Achieving high speed physical layer security is a constant pursuit but critical challenge for the information society. In this paper, a novel symbol-by-symbol optical phase encryption technique relying on ultra-long, reconfigurable optical phase patterns and commercial off-the-shelf dispersive components is proposed for high speed physical layer security. A record 40Gb/s secure optical communication

This study demonstrates the first athermal polysilicon Mach-Zehnder interferometer (MZI) based on strip and subwavelength grating waveguides in commercialized bulk CMOS without any process modification. As-fabricated MZI exhibits a temperature sensitivity of ±4 pm/°C over 1500~1600 nm wavelength range with a slope of −0.055 pm/°C/nm. This wavelength filtering device is therefore immune from the temperature

Linear phased arrays enable simultaneous tunable focusing and scanning. Using an electrostatically actuated, high-speed linear phased array of MEMS mirrors, we demonstrate cylindrical focusing with 90% optical efficiency up to 0.008 numerical aperture (NA) with simultaneous beam steering. Single focus scanning is demonstrated up to an NA of 0.013, at which point the focus splits, creating a multifocal

This letter presents the development and characterization of a Fabry-Perot interferometer (FPI) for the detection of dissolved ammonia. The FPI cavity is obtained by the alignment of two single mode fibers (SMFs), where a mixture of ultraviolet (UV) curable resin and Oxazine 170 perchlorate is positioned in the gap between both SMFs. The sensor operation principle is based on the chemical reaction

Practical deployment of elastic optical networks requires key enabling technologies supporting the miniaturization of flexible optical transponders for provisioning large-bandwidth services at low-cost per users. A silicon photonics (SiP) reconfigurable optical frequency comb (OFC) demultiplexer based on passive optical filtering exhibiting a minimum spurious tone rejection (STR) of nearly 30dB at

In the original letter [1] , Equations 1, 2 and 3 now read as

We demonstrate that a graded-index plastic optical fiber (GI POF) enables higher-quality radio-over-fiber (RoF) transmission of an orthogonal frequency-division multiplexing (OFDM) signal, compared with a conventional multimode fiber, for short-distance household applications (< 100 m). It is shown that the improvement in OFDM signal transmission, using the GI POF, can be attributed to the reduction

A cladding-pumped all-fiber chirped femtosecond pulse Yb-doped mode-locked laser operating near 977 nm was demonstrated for the first time. Nonlinear polarization evolution was used as the mode-locking mechanism. The laser was self-starting and extremely stable (the stability of the repetition rate of 41.6 MHz was better than that of 15 Hz). Amplification near 977 nm was achieved using a specially

In this paper, we fabricated a novel tungsten disulfide (WS 2 ) saturable absorber (SA) using sol-gel technology and successfully applied it into a Q-switched solid-state laser for the first time. By using sol-gel technology, WS 2 materials are completely separated into sol-gel silica glass, which can effectively protect the WS 2 materials from oxidation and other damages. Inserting the WS 2 SA into

In this study, we propose a novel all-optical switch that is controlled by the thermo-optic effect in a silicon ring resonator with a metal cladding layer. A pump light is efficiently converted into heat through absorption by a metal layer, causing a resonant wavelength shift. The burst-switching measurement reveals a switching on/off ratio of 5.7 dB at the drop-port with a pump power of 20 mW.

We demonstrate a carrier-envelope-offset-stabilized, self-referenceable Yb:CaF 2 oscillator pumped by a single-mode laser diode. By exploiting mode-locking regime based on simultaneous action of the SESAM and the Kerr lens effect we achieved self-starting generation of 85 fs pulses with a peak power approaching 47 kW. The carrier-envelope offset detection scheme was based on a standard $f$ -to- $2f$

We demonstrate optical wireless transmission with two-dimensional (2D) beam-steering using an optical phased array (OPA). The OPA consists of 64-elements of electro-optic p-i-n phase shifters and thermo-optic tunable n-i-n grating radiators, employed for 2D beam-steering in the transversal and longitudinal directions. The design of the transmitter and receiver device parameters allowed the error-free

We incorporate two major types of SDM fibers (i.e. few mode fibers and multicore fibers) in a micro-optic collimator assembly and realize fully integrated multiport SDM fiber components (e.g. $1\times 2$ and $2\times 2$ beam splitters). The device fabrication procedure for SDM fibers is similar to that for a standard single mode fiber, but more accurate fiber alignment (e.g. lateral positioning for

A Carrier Suppressed Single Sideband(CS-SSB) modulation decoupling control technique based on Dual Parallel Mach-Zehnder Modulator (DPMZM) is proposed to solve the problem that the bias point of the DPMZM leads to the degradation of the modulation signal under the influence of ambient temperature, fiber coupling loss or other factors. This technique introduces three non-disturbing dithering voltages

We experimentally investigate the generation of high-order modes (HOMs) with flexible switchable output. Cascaded acoustically induced fiber gratings (AIFGs) act as mode converters. A periodic micro-bending in the AIFG is produced by travelling flexural acoustic wave, and two modes with adjacent azimuthal numbers can be coupled to each other. Different HOMs (LP 21a/b and LP 11a/b ) could be obtained

An optically tunable in-core Mach-Zehnder interferometer (MZI) based on the photoexcitation dynamics of nitrogen-doped graphene quantum dots (NGQDs) is demonstrated. The tunable MZI is fabricated by depositing NGQDs into a femtosecond laser ablated microgroove in the core. Combining both the high sensitivity to the external refractive index change of the MZI itself and the quantum confinement effect

We report the demonstration of fiber Bragg grating (FBG) fabricated in silica capillary fiber by use of femtosecond laser. The FBG is inscribed in the silica cladding surrounding the air core by a transversal scanning method through a phase mask. Multimode resonances which result from the overlap of the grating structure and the cladding modes transmitting in the capillary fiber, are observed in the

We demonstrate the first W-band optoelectronic oscillator (OEO), that oscillates at 94.5 GHz with a measured single side band (SSB) phase noise of −101 dBc/Hz at an offset frequency of 10 kHz from the carrier. Side mode suppression of more than 65 dB has been achieved by using injection locking. This OEO has potential application as a signal source in emerging W-band applications (e.g. fiber-wireless

In this work, a $2.5\times 2.5$ mm 2 large-area 4H-SiC Schottky barrier photodiode with a grid-shaped semitransparent metal electrode is designed and fabricated for extreme ultraviolet (EUV) detection. The photodiode shows an ultra-low leakage current of ~3 pA under 20 V reverse bias at room temperature. Based on a synchrotron radiation source, the photo-response characteristics of the photodiode is

Current optical coherent transponders technology is driving data rates towards 1 Tb/s/ $\lambda $ and beyond. This trend requires both high-performance coded modulation schemes and efficient implementation of the forward-error-correction (FEC) decoder. A possible solution to this problem is combining advanced multidimensional modulation formats with low-complexity hybrid HD/SD FEC decoders. Following

A tunable microwave photonic filter (MPF) based on a polarization beam splitter (PBS) and waveguide grating true-time delay line (TTDL) is proposed and demonstrated experimentally. Taking advantage of the high birefringence property of lithium niobate (LN), the PBS is achieved by a simple structure in a short length. The TTDL consists of an LNOI waveguide grating and flexible electrodes covering along

In a practical 4- $\lambda $ coarse wavelength division multiplexing (CWDM) intensity modulation direct detection (IM/DD) system, different wavelength channels achieve different transmission performances due to 1) inter-channel component differences and 2) chromatic dispersion (CD) – chirp interaction. Large channel performance discrepancies could significantly degrade the average pre- forward error

Fiber Bragg grating (FBG) demodulation based on microwave photonics (MWP) would have a high resolution but the measurement range is usually limited. Here, we propose an FBG demodulation system based on wavelength to optical fiber relative delay (OFRD) mapping, where the signal reflected by the FBG is first modulated by an RF signal and then sent to a dispersion compensation fiber (DCF). The OFRD can

The relative average inter-core crosstalk (IC-XT) among wavelength-division multiplexed (WDM) optical channels in a quasi-homogeneous two-core fiber system exhibiting slight differences on the propagation constant, inverse group-velocity, and the group-velocity dispersion (GVD) between cores is numerically investigated. This analysis is performed using a theoretical formalism that includes fiber nonlinearities

Visible light communication (VLC) has drawn significant attention in recent years. Though high-speed visible-light sources have seen significant advances, commercially available photodetectors have low wavelength selectivity and modulation bandwidth in the near-violet-blue wavelengths, making them a bottleneck in VLC links. Here we show a record 7.4-Gbit/s visible-light communication link using a

Hybrid OFDM-digital filter multiple access (OFDM-DFMA) PONs exploit software configurable digital shaping filters in ONUs to multiplex multiple gapless OFDM channels at different radio frequencies and utilize a single FFT operation-based pipelined DSP procedure in the OLT to simultaneously de-multiplex/demodulate all OFDM signals from various ONUs without requiring any digital matching filters. In

Digital predistortion is topic of significant interest in telecommunications – both in the wireless radio field and, more recently, in photonics. In the present letter, the authors undertake a sensitivity analysis of various digital predistortion algorithms. Using recent metamodeling techniques designed for efficient stochastic analysis, the authors show that using predistortion not only leads to a

We present mode-selection in a laser and an amplifier from a multicore Ytterbium (Yb) doped step-index fiber with six large mode area and low numerical aperture (NA) cores, fabricated using a combination of chelate delivery system (CDS) and stack and draw technique. The six cores are placed in a ring shape with each core having a diameter of $\sim 19~\mu \text{m}$ and NA of ~0.068, or V-number of ~3

Chaotic Brillouin Dynamic Grating (BDG) can be individually generated and stably maintained due to the thumbtack-correlation characteristics of chaotic laser, which has its particular advantages over the conventional BDGs. However, the fluctuant sidelobes around chaotic BDG induced by the inherent characteristic of chaotic laser have an adverse effect on the signal-to-noise ratio (SNR) of chaotic BDG

We investigate the effects of the hole transport layer (HTL) and the buffer layer in a CdSe/ZnS quantum-dot LED (QLED) to reveal several important performance trade-offs in the QLED design. Our fabricated QLED samples show that, among the three common HTL materials, poly(9-vinlycarbazole) (PVK), poly[N,N’-bis(4-butylphenyl)-N,N’-bis(phenyl)-benzidine] (poly- TPD), and poly(9,9-dioctylfluorene-co-N

The introduction of 5G enhanced mobile broadband (eMBB) services has brought unprecedented bit-rate demands to the optical transport infrastructure, which can hardly be supported through cost-effective digital fronthauling solutions. This opens up a whole new opportunity for bandwidth-efficient radio-over-fiber (RoF) analog fronthaul transmission, which avoids the well-known bandwidth multiplication

We demonstrate high-speed operation of a hybrid modulation laser. The intra-cavity loss modulation (ICLM) section, which acts as an external cavity, enables the photon-photon resonance (PPR) effect to be introduced to the laser. We confirm that the modulation bandwidth of the hybrid modulation laser was able to be broadened to more than 66 GHz.

A simple, highly sensitive fiber Fabry-Perot interference sensor based on polydimethylsiloxane (PDMS) is proposed and demonstrated for simultaneous measurement of gas pressure and temperature. The sensor is fabricated by fusion splicing a short segment of hollow capillary tube to a standard single mode fiber and injecting PDMS in sections into capillary tube, then three reflecting surfaces are formed

This work presents an experimental evaluation of single-channel long-distance transmission over a homogeneous single-mode multicore fiber. We compare the detection of 20 GBaud polarization-multiplexed quadrature-phase-shift-keyed signals with and without the use of high-order multiple-input multiple output systems, to undo crosstalk-induced degradation, combined with digital back-propagation to undo

We present the generation of 12.1 ns frequency chirped pulses from a distributed feedback laser diode via injection current modulation and demonstrate its application to absorption-based methane sensing at 1650.9 nm. The chirp spectral distribution is found to be significantly impacted by the transient dynamics of these short pulses. A simplified, two-part model is used to evaluate the chirp property

In the present letter, Pd/Al 2 O 3 /MoS 2 /ITO MISM UV photodetector structure is proposed and analyzed. For the proposed photodetector, responsivity is 488 A/W, detectivity is $8.22\times 10 ^{12}$ Jones and external quantum efficiency (EQE) is $1.9\times 10 ^{5}$ %, at wavelength 308nm, 1V bias and light intensity $13.6~\mu \text{W}$ /cm 2 . Thus, proposed MISM photodetector device gives significant

In this correction, we correct a typo error in equation (1) that appears in our letter “All-Solid Athermal Multimode-Interference Cascaded Device for Wavelength-Locking” [1] .

Measuring the topological charge(TC) of optical vortices is of great importance in applications of vortex beams. A flexible and convenient method to determine the TC of an optical vortex is proposed by using an elliptical airy phase mask (EAPM). The mask can be embedded into a typical vortex generation setup, in which no additional optical elements are required. The number and the sign of TC are respectively

We experimentally demonstrated a chemical sensing system for Cu 2+ detection based on an optofluidic laser. A Fabry–Perot cavity within a square quartz capillary fluidic channel was built to enable optofluidic lasing. Rh6G-HS (Rh6G, hydrazine hydrate, salicylaldehyde), a rhodamine derivative was used as the laser gain medium, and the switching mechanism of spirolactam (fluorescence: “off”) to ring-opened

In the applications of wave-front detection using second-harmonic generation, the spatial phase distribution needs to calculate accurately before and after frequency doubling in real-time. This letter presents a learning-based method called extreme learning machine to fit the corresponding relationship of phase between the fundamental frequency wave and the second-harmonic. The Zernike coefficients

In this work, the after-pulse properties of 4H-SiC ultraviolet (UV) avalanche photodiodes (APDs) working in gated quenching mode are firstly characterized by using a double gate method. The after-pulse probability is determined as a function of delay time at various overbias voltages and temperatures. It is found that the after-pulse probability of 4H-SiC APDs would decrease at higher chip temperature

Multimode fiber (MMF) based endoscopy could reach high resolution and is fine enough for vivo imaging. However, the received images are speckles due to the mode crosstalk and sensitivity to environment of MMF, which makes image reconstruction the main challenge. We propose to use pre-trained autoencoder for image reconstruction from speckles to original images, which shows high performance and fast

We demonstrate flat supercontinuum (SC) generation in a piece of step-index tellurite fiber pumped by a noise-like mode-locked fiber laser in the deep normal dispersion region. The noise-like pulse emitted from a simple all-fiber mode-locked laser is used as the pump directly and the cascaded stimulated Raman scattering leads to the spectral broadening to the long wavelength region. Flat SC spanning

Radiofrequency ablation (RFA) is a clinical technique which inactivates targeted biological tissues by heating to remove tumors or to cure diseases like atrial fibrillation. Temperature is a fundamental parameter for ablation dose control and treatment effect evaluation. This paper presents the design, fabrication and characterization of an all-optical fiber ultrasound temperature measurement probe

Skin plays a significant role in human body function and its collagen states change during the human skin ageing process, which affects skin function. We previously reported on geometry-dependent spectroscopic contrast achieved by spectroscopic micro-optical coherence tomography ( $\text{S}\mu $ OCT), which discovered that transversely oriented and regularly arranged nano-cylinders selectively backscatter

In an earlier study micro-LED micro display (< 1 inch) on silicon CMOS backplane was demonstrated for augmented reality (AR) applications. Here we report the feasibility of wafer-level monolithic integration of micro-LEDs on glass substrate/backplane. Such issues as the cracking of GaN epitaxial layer, the deviation of alignment, and the peeling of insulator are discussed. SU-8 is proposed as the insulator