This study proposes a novel, to the best of our knowledge, development of fluorotellurite glass fiber Bragg gratings (FBGs). Shell-like morphology was achieved using a single femtosecond laser pulse illuminated through the fiber’s polymer coating. Different FBG fabrication methods and parameters were systematically studied to optimize performance. The fluorotellurite FBG exhibited a high sensitivity

We present a spectrum-tunable fiber Bragg grating (FBG) based on a unique compress-twist deformation mode of non-rigid origami. By applying axial displacement on the FBG-bonded Kresling-ori, a non-uniform strain field emerges. The mechanics-induced non-uniform strain can shift the wavelength of an apodized unchirped FBG and/or transform an apodized unchirped FBG to a chirped one. For the spectrum-shaping

Functional nanocoatings of hollow-core microstructured optical fibers (HC-MOFs) have extended the domain of their applications to biosensing and photochemistry. However, novel modalities typically come with increased optical losses since a significant surface roughness of functional layers gives rise to additional light scattering, restricting the performance of functionalization. Here, the technique

This Letter reports a novel helical sapphire fiber Bragg grating (HSFBG) in a single crystal sapphire fiber with diameter of 60 µm fabricated by a 515 nm femtosecond laser. Due to the large refractive index modulation region and high structural symmetry of the HSFBGs, high-reflectivity and high-quality spectra can be prepared and additionally have good bending resistance. The spectral properties of

Noiseless optical components are critical for applications ranging from metrology to quantum communication. Here, we characterize several commercial telecom C-band fiber components for parasitic noise using a tunable laser. We observe the spectral signature of trace concentrations of erbium in all devices from the underlying optical crystals including ${\rm YVO}_{4}$, ${\rm LiNbO}_{3}$, ${\rm TeO}_{2}$

We show that accelerated nonlinear imaging, such as stimulated Raman scattering and pump–probe imaging, is enabled by an order of magnitude reduction of data acquisition time when replacing the exponentially-weighted-moving-average low-pass filter in a lock-in amplifier with a simple-moving-average filter. We show that this simple-moving-average (box) lock-in yields a superior signal-to-noise ratio

Single-pixel imaging (SPI) has been intensively studied in recent years for its capacity to obtain 2D images using a non-pixelated detector. However, the traditional modulation modality using an iteratively refreshed spatial light modulator has significantly restricted its imaging speed, which is a primary barrier to its widespread application. In this work, we propose and demonstrate a new, to the

Current optical communication systems rely on the use of wavelength division multiplexing (WDM) to keep up with the increasing data rate requirements. The wavelength demultiplexer is the key component to implement WDM systems. In this Letter, we design and experimentally demonstrate a demultiplexer based on a curved grating waveguide geometry that separates eight channels with a spacing of 10 nm (1249

The bidirectional ultrafast fiber laser is a promising light source for dual-comb applications. The counter-propagating geometry could lead to soliton interaction through gain sharing, as well as the possible outcome of polarization instability. However, the polarization dynamics hidden behind the soliton interaction process in bidirectional fiber lasers were rarely investigated. Herein, we report

Electrically pumped semiconductor mode-locked lasers (SMLs) are promising in a wide range of applications due to compact size, high energy efficiency, and low cost. However, the long gain interaction length increases the spontaneous emission noise. In this Letter, an external cavity structure is adopted to improve the SML noise performance, as well as the flexibility to adjust the repetition rate.

In this work, we theoretically demonstrate the giant increment of the transversal magneto-optical Kerr effect in a type II hyperbolic metamaterial composed of four pairs of dielectric/metal layers, where the dielectric material presents magneto-optical activity. The enhancement is a consequence of high localization of the electromagnetic field inside the metamaterial given by excitation of the lowest

One of the key measures to secure reliable fever screening is to calibrate a thermal imager with an accurate flat-plate blackbody device in real time. We provide durable perfect blackbody plates with both high emissivity of ${\gt}{0.998}$ and good heat transfer, ideal for a high-precision reference radiation source. Reflectance measurements and heat transfer simulation demonstrate that a micro-cavity

Robust models for single-fiber reflectance (SFR) are relatively complex [Opt. Lett. 45, 2078 (2020) [CrossRef] ] due to overlapping of the illumination and collection areas that entails probability weighting of the spatial integration of photon-remission. We demonstrate, via analytical means for limiting cases and Monte Carlo simulation of broader conditions, that diffuse photon-remission collected

Here, we report hitherto unobserved local field (LF)-assisted pump wavelength-dependent nonlinear optical (NLO) effects of three-photon (3PA)-induced four-photon absorption (4PA) at 532 nm and two-photon-induced 3PA at 730 nm in triangular-shaped core–shell Ag-Au nanoparticles (TrAg@Au) by femtosecond Z-scan. The shell thickness-dependent enhancement in the LF is observed by a COMSOL simulation. The

We distinctly reveal the difference in the exciton generation processes in phosphorescent organic light-emitting devices with an exciplex-type co-host and a single host. Excitons in the co-host consisting of 4,4,4-tris(N-carbazolyl)-triphenylamine and 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene are created via efficient energy transfer from the exciplex to the phosphorescent dopant. In contrast, excitons

A novel, to the best of our knowledge, tiny velocity measurement system is proposed and demonstrated. This proposed system employs an interference structure in which the reference and measurement paths are filled by two light beams carrying opposite-sign orbital angular momentum (OAM), respectively. The tiny velocity to be measured in the measurement path causes the change of the light path and results

In this Letter, we perform a comprehensive investigation on the optical characterization of micro-sized deep-ultraviolet (DUV) LEDs (micro-LEDs) emitting below 280 nm, highlighting the light extraction behavior in relation to the design of chip sidewall angle. We found that the micro-LEDs with a smaller inclined chip sidewall angle (${\sim}{{33}}^\circ$) have improved external quantum efficiency (EQE)

We propose an approach for fast random number generation based on homemade optical physical unclonable functions (PUFs). The optical PUF is illuminated with input laser wavefront of continuous modulation to obtain different speckle patterns. Random numbers are fully extracted from speckle patterns through a simple post-processing algorithm. Our proof-of-principle experiment achieves total random number

In this work, we report a simple and effective method for enhancing the photonic spin Hall effect (SHE) via singularity induced by destructive interference in an ultrathin uniaxial slab. Deriving from anisotropy, the incident angles corresponding to destructive interference for $p$- and $s$-polarized waves will be deviated, leading to an enhancement peak in transverse spin shift. Interestingly, by

Light’s internal reflectivity near a critical angle is very sensitive to the angle of incidence and the optical properties of the external medium near the interface. Novel applications in biology and medicine of subcritical internal reflection are being pursued. In many practical situations, the refractive index of the external medium may vary with respect to its bulk value due to different physical

The infrared reflectance spectrum of cubic boron phosphide (BP) single crystals shows a very narrow Reststrahlen band, indicating a small TO-LO (transverse optical-longitudinal optical) splitting. To study the phonon thermal behavior of the ${\rm TO}(\Gamma)$ and the ${\rm LO}(\Gamma)$ of ${^{10}}{\rm BP}$, ${^{\rm nat}}{\rm BP}$, and ${^{11}}{\rm BP}$ bulk single crystals, temperature-dependent infrared

The theoretical framework for a novel, to the best of our knowledge, stimulated Raman spectroscopy process using a UV probe laser pulse train is formulated and simulated. The laser pulse train consists of multi-femtosecond micro-pulses separated by a varying time duration, having a fixed carrier frequency. The comb-like probe spectrum undergoes self-beating. By appropriately varying the separation

This publisher’s note contains corrections to Opt. Lett. 46, 4216 (2021) [CrossRef] .

Functional nanocoatings have allowed hollow-core microstructured optical fibers (HC-MOFs) to be introduced into biosensing and photochemistry applications. However, common film characterization tools cannot evaluate the coating performance in situ. Here we report the all-optical noncontact characterization of the HC-MOF coating in real time. Self-assembled multilayers consisting of inversely charged

In this Letter, we introduce a computer-generated hologram (CGH) optimization technique that can control the randomness of the reconstructed phase. The phase randomness significantly affects the eyebox size and depth of field in holographic near-eye displays. Our proposal is to synthesize the CGH through the sum of two terms computed from the target scene with a random phase. We set a weighting pattern

We report a method for measuring the exposure response coefficient of polarization-sensitive media using the tensor theory of polarization holography. According to the theory of polarization holography based on the tensor method, the exposure response coefficient of polarization-sensitive media is not only determined by the materials but also affected by the exposure energy. The exposure response coefficient

Making analogy with atomic physics is a powerful tool for photonic technology, witnessed by the recent development in topological photonics and non-Hermitian photonics based on parity–time symmetry. The Mollow triplet is a prominent atomic effect with both fundamental and technological importance. Here we demonstrate the analog of the Mollow triplet with quantum photonic systems. Photonic entanglement

We experimentally generate an orbital-angular-momentum (OAM) beam with a tunable mode order over a range of wavelengths utilizing an integrated broadband pixel-array OAM emitter. The emitter is composed of a 3-to-4 coupler, four phase controllers, and a mode convertor. An optical input is split into four waveguides by the coupler. Subsequently, the four waveguide fields are coherently combined and

We investigate the spectral filtering effect on the mid-infrared ultrafast ${{\rm Er}^{3 +}}$-doped ZBLAN fiber laser based on nonlinear polarization evolution (NPE). A broad wavelength tuning range from 2720 nm to 2800 nm is achieved using a diffraction grating as the narrowband filter. Furthermore, numerical simulations are also carried out so that, by inserting a highly nonlinear fiber combined

Fourier ptychographic microscopy (FPM), as an emerging computational imaging method, has been applied to quantitative phase imaging with resolution bypassing the physical limit of the detection objective. Due to the weak illumination intensity and long image acquisition time, the achieved imaging speed in current FPM methods is still low, making them unsuitable for real-time imaging applications. We

We demonstrate that spectral peak power of negatively chirped optical pulses can acquire a blueshift after amplification by a semiconductor optical amplifier. The central wavelength of a transform limited optical pulse translates over 20 nm towards a shorter wavelength after propagation in a single-mode fiber and semiconductor optical amplifier. A chirped Gaussian pulse with full width at half maximum

A novel, to the best of our knowledge, mid-infrared chalcogenide (ChG) on magnesium fluoride (${{\rm MgF} _{2}}$) waveguide gas sensor was fabricated by using the lift-off method. ${{\rm MgF} _{2}}$ was used as a lower cladding layer to increase the external confinement factor for enhancing light–gas interaction. Wavelength modulation spectroscopy (WMS) was used in carbon dioxide (${{\rm CO} _{2}}$)

We report an omnidirectional light absorption enhancement of a perovskite solar cell (PSC) using antireflection (AR) film with soft imprinted microstructures from master molds via holographic lithography technology, which has high throughput and repeatability. The PSC’s omnidirectional power conversion efficiency (PCE) enhancement is achieved by reducing Fresnel surface reflections and enhancing the

In this Letter, a dynamically tunable metasurface, which is based on antimony trisulfide, is introduced. In this structure, first a metal-insulator-metal (MIM) nanocavity is optimized in a way that, upon phase change, the visible response switches from a transmissive colored window into a reflective mirror. Later, an indium tin oxide nanoantenna is integrated on the MIM cavity to provide antireflection

We present here a theoretical analysis of the interaction between an ideal two-level quantum system and a super-oscillatory pulse, like the one proposed and successfully synthesized in [J. Opt. 23, 075604 (2021) [CrossRef] ; arXiv:2106.09192 (2021)]. As a prominent feature, these pulses present a high efficiency of the central super-oscillatory region in relation to unavoidable sidelobes. Our study

In this work, we present a panoramic digital holographic system for the first time capable of obtaining 3D information of a quasi-cylindrical object by using a conical mirror. The proposed panoramic digital holographic system is able to scan the entire surface of the object to determine the amplitude and phase simultaneously. This paper demonstrates the feasibility of analyzing quasi-cylindrical objects

Traditional distorting mirrors utilize curved surfaces to produce distorted virtual images, i.e., illusions. Here we propose the concept of flat distorting mirrors (FDMs) based on gradient metasurfaces and investigate the shape, orientation, and position of the virtual images generated by such FDMs through a ray optics approach. The virtual images can be controlled by varying the distribution of the

In this work, we present an ultra-fast line-field optical coherence elastography system (LF-OCE) with an 11.5 MHz equivalent A-line rate. The system was composed of a line-field spectral domain optical coherence tomography system based on a supercontinuum light source, Michelson-type interferometer, and a high-speed 2D spectrometer. The system performed ultra-fast imaging of elastic waves in tissue-mimicking

Collecting significant and measurable signals from the typically omnidirectional emission of nanoscale emitters is challenging. To improve the collection efficiency, it is essential to deterministically place the emitters in desired locations and design mode converters to match the modes of emission to those of the collection system. In this Letter, we propose the deterministic placement of nanoscale

A multiple-access underwater frequency transfer scheme using terminal phase compensation is demonstrated. With this scheme, a highly stable 100 MHz frequency signal was disseminated over a 3 m underwater link for 5000 s. The timing fluctuation and fractional frequency instability were both measured and analyzed. The experimental results show that with the phase compensation technique, the total root-mean-square

We present a full image reconstruction methodology in frequency-domain photoacoustic (PA) microscopy using a low-cost I/Q demodulator for the recording of the amplitude and phase of the signals. By modulating the intensity of a continuous-wave diode laser at 10 MHz, we have been able to provide accurate optical absorption images and surface reconstructions of phantom samples, comparing also the extracted

We investigate the modal properties of a beam carrying orbital angular momentum (OAM) generated by a circular array (ring) of multiple micro-ring emitters (rings) analytically and via simulation. In such a “ring-of-rings” structure, $N$ emitters generate $N$ optical vortex beams with the same OAM-order ${{l}_0}$ at the same wavelength. The output beam is a coherent combination of the $N$ vortex beams

We consider a topological Floquet insulator realized as a honeycomb array of helical waveguides imprinted in a weakly birefringent medium. The system accounts for four-wave mixing occurring at a series of resonances arising due to Floquet phase matching. Under these resonant conditions, the system sustains stable linearly polarized and metastable elliptically polarized two-component edge solitons.

A four-channel coarse wavelength division multiplexing (CWDM) (de)multiplexer on a thin film lithium niobate–silicon rich nitride hybrid platform has been designed, fabricated, and experimentally measured. Enabled by cascaded multimode waveguide Bragg gratings, the (de)multiplexer has a box-like spectral response, wide 1-dB bandwidth (10 nm), low excess loss ($\lt{1.08}\;{\rm dB}$), and low channel

Liquid crystal light valves (LCLV) are optically addressable spatial light modulators that allow controlling the phase and amplitude properties of optical beams. We show that sub-milliseconds phase and amplitude modulations can be obtained when operating the LCLV in the transient dynamic mode by setting the working point close to the saturation of the response. Thanks to the large birefringence of

The synergistic integration of optofluidic and surface enhanced Raman scattering (SERS) sensing is a new analytical technique that provides a number of unique characteristics for enhancing the sensing performance and simplifying the design of microsystems. Here, we propose a reusable optofluidic SERS sensor by integrating Au nanoisland substrate (AuNIS)-coated fiber into a microfluidic chip. Through

We theoretically make plausible and numerically verify that when a high-efficiency, polarization-independent grating, designed to work at or near Littrow mounting, is used in conical Littrow mounting, its high efficiency and polarization independence can be very well maintained at a large off-principal-plane deviation angle. This finding provides a new degree of freedom to the design of high-efficiency

A broadband vortex beam generator provides a promising solution for various applications. Since the space-charge wave of the free-electron bunch inherently covers a wide frequency range, the free-electron-driven devices can be utilized to generate broadband radiation. This work presents a wideband tunable multi-mode vortex beam generator based on the Smith–Purcell radiation (SPR) from a helical grating

We experimentally demonstrate the possibility of quasi-adiabatic conversion of ${{\rm LP}_{11}}$ modes to vortex modes in a twisted highly birefringent fiber with a gradually increasing twist rate. Based on the value of the effective indices, the ${{\rm LP}_{11}}$ modes are selectively converted to right- and left-handed circularly polarized vortex modes ${{\rm HE}_{21}}$ with a total angular momentum

We experimentally verified that Tomlinson–Harashima (TH) pre-coding for an optical coherent system can enhance the speed of polarization division multiplexing (PDM) 16 quadrature amplitude modulation (QAM) signal to be higher than 135 GBaud with 120 GSa/s digital-to-analog converter (DAC) and electrical/optical/electrical bandwidth of the system narrower than 57 GHz at $- 30\;{\rm dB}$. The improvement

Existing studies of the ultraviolet (UV) channel mainly focus on non-line-of-sight (NLOS) scenarios, while line-of-sight (LOS) scenarios are generally neglected since obstacles sometimes block them. To fill this gap, a UV diffused-LOS channel model in the presence of an obstacle is proposed for the first time, to the best of our knowledge. For easy interpretation, the whole derivation is combined with

We experimentally demonstrate remotely powered, controlled, and monitored optical switching. The control signal of the switch is modulated on an optical wave and sent from a transmitter. At the switch location, the control signal is converted from an optical to an electrical signal to drive the switch. In addition, to provide electrical power at the switch location, optical power is sent from a distance

A cost-effective and robust digital signal processing (DSP) scheme is proposed and demonstrated experimentally in a coherent 61 GBaud PDM 16QAM system. In our scheme, multi-stage DSP blocks are used to deal with channel effects, transceiver in-phase and quadrature (IQ) skew, and phase noise. A ${4} \times {4}$ real-valued multiple-input multiple-output (RV-MIMO) with $ N_{1} $ taps is for polarization

Visible light communication (VLC) beyond 10 Gbps is an important characteristic that can support the future 6 G high-capacity requirements. On the one hand, in order to break the electro-optics (E-O) bandwidth limitation of the light-emitting diodes (LEDs), we fabricated two high-bandwidth (${\gt} {\rm gigahertz}$) single wetting layer micro-LEDs with 50 and 75 µm active regions. On the other hand

Speckle correlation imaging (SCI) has found tremendous versatility compared with other scattering imaging approaches due to its single-shot data acquisition strategy, relatively simple optical setup, and high-fidelity reconstruction performance. However, this simplicity requires SCI experiments to be performed strictly in a darkroom condition. As background noise increases, the speckle contrast rapidly

An efficient method is proposed for the calculation of the optical force of multiple nanoparticles. In this method, the optical force is calculated by integrating the Maxwell stress tensor (MST) over a closed surface encompassing the nanoparticle. The electromagnetic (EM) field required for evaluating the MST is computed with the coupling theory of quasinormal modes (QNMs), in which the EM field is

Tensile deformation uniformity of material has been studied with a stretchable polymer based holographic sensor. The diffraction spectrum distribution of a holographic grating with a large area as a main response parameter is scanned. A linear spatial distribution of peak wavelength provides an important foundation for exploring the tensile uniformity. The same ratio of wavelength to position confirms

We propose a simple and effective method for generating a vector light field based on the faithful reconstruction (FR) effect of polarization holography, where the arbitrary linear polarization waves can be faithfully reconstructed by the polarization-sensitive recording media. The scheme incorporates the tunable and switchable dynamics exposure system to manufacture vector beams. By regulating the

A concise and powerful method for dual-wavelength digital holography (DWDH) is proposed. By designing a new algorithm, this proposed method bypasses the phase synthesis process and directly obtains the thickness distribution of the object. This method can enlarge the range of measurement with strong noise resistance. For example, noise analysis results show that the proposed method reduces the reconstruction

Coherence gating is typically exploited for imaging through disordered media by least-scattered (ballistic) light. Ballistic light-based approaches produce clear images only when the proportion of ballistic to multiply scattered (non-ballistic) light is relatively high. To overcome this limitation, we counterintuitively utilize the coherence gate to image by the non-ballistic light, enabling us to