Window size dependence of gain and bandwidth in avalanche photodiodes with multiple multiplication layers under near Geiger-mode operation.

We consider avalanche photodiodes (APDs) functioning under near Geiger-mode operation for extremely weak light (single or several photons) detection, such as in LiDAR receivers. To meet such demands, APDs which simultaneously have a large active window size, moderate bandwidth (∼GHz), and high internal gain (responsivity), are highly desired. However, it is difficult to design APDs capable of meeting the afore-mentioned performance requirements due to the intrinsic limitations of the gain-bandwidth product (GBP).

Linearization of wavelength sweeping lasers for the construction of 4-D FMCW LiDAR images of slow-moving objects using baseband beat note signals.

A FMCW LiDAR system of both the distributed feedback laser and external cavity laser is established in baseband beat notes, rather than up-conversion to an intermediate frequency to exclude flicker noise. Meanwhile, utilizing fast-scanning MEMS mirrors, high-quality real-time (1 fps) 4-D images of the slow-moving object (10 mm/s) can be directly constructed at the baseband with a central frequency as low as 100 kHz and a small Doppler shift. The proposed LiDAR architecture based on such a low-frequency baseband significantly improves the optical power budget on the transmitter side and eliminates the costly high-speed sampling circuits on the receiver side.

Nonlocal Metasurface with Chiral Exceptional Points in the Telecom-Band.

The exceptional point (EP) is the critical phase transition point in parity-time () symmetry systems, offering many unique physical phenomena, such as a chiral response. Achieving chiral EP in practical applications has been challenging due to the delicate balance required between gain and loss and complicated fabrication, limiting both working band and device miniaturization. Here, we proposed a nonlocal metasurface featuring orthogonal gold nanorods, where loss modulation is achieved through rod size and lattice pitch.

Simultaneous enhancement of the bandwidth and responsivity in high-speed avalanche photodiodes with an optimized flip-chip bonding package.

The enhancement in responsivity of photodiodes (PDs) or avalanche photodiodes (APDs) with the traditional flip-chip bonding package usually comes at the expense of degradation in the optical-to-electrical (O-E) bandwidth due to the increase of parasitic capacitance. In this work, we demonstrate backside-illuminated InAlAs based APDs with novel flip-chip bonding packaging designed to relax this fundamental trade-off. The inductance induced peak in the measured O-E frequency response of these well-designed and well-packaged APDs, which can be observed around its 3-dB bandwidth (∼30 GHz), effectively widens the bandwidth and becomes more pronounced when the active diameter of the APD is aggressively downscaled to as small as 3 µm.

Parity-time symmetry breaking optical nanocircuit.

Gain and loss balanced parity-time (PT) inversion symmetry has been achieved across multiple platforms including acoustics, electronics, and photonics. Tunable subwavelength asymmetric transmission based on PT symmetry breaking has attracted great interest. However, due to the diffraction limit, the geometric size of an optical PT symmetric system is much larger than the resonant wavelength, which limits the device miniaturization.

Hypoglycemic Effect of Nobiletin via Gut Microbiota-Metabolism Axis on Hyperglycemic Mice.

Scope: Prediabetes and diabetes are major public health problems worldwide without specific cure currently. Gut microbes have been recognized as one of the vital therapeutic targets for diabetes. The exploration that nobiletin (NOB) whether affects gut microbes provides a scientific basis for its application.

Separated electrodes for the enhancement of high-speed data transmission in vertical-cavity surface-emitting laser arrays.

In this work, a novel design for the electrodes in a near quasi-single-mode (QSM) vertical-cavity surface-emitting laser (VCSEL) array with Zn-diffusion apertures inside is demonstrated to produce an effective improvement in the high-speed data transmission performance. By separating the electrodes in a compact 2×2 coupled VCSEL array into two parts, one for pure dc current injection and the other for large ac signal modulation, a significant enhancement in the high-speed data transmission performance can be observed. Compared with the single electrode reference, which parallels 4 VCSEL units in the array, the demonstrated array with its separated electrode design exhibits greater dampening of electrical-optical (E-O) frequency response and a larger 3-dB E-O bandwidth (19 vs.

Avalanche photodiodes with multiple multiplication layers for coherent detection.

We demonstrate a novel avalanche photodiode (APD) design which fundamentally relaxes the trade-off between responsivity and saturation-current performance at receiver end in coherent system. Our triple InAlAs based multiplication (M-) layers with a stepped electric (E-) field inside has more pronounced avalanche process with significantly less effective critical-field than the dual M-layer. Reduced E-field in active M-layers ensures stronger E-field allocation to the thick absorption-layer with a smaller breakdown voltage (V) resulting in less serious space-charge screening effect, less device heating at high output photocurrent.

Mechanically Robust, Self-Repairable, Shape Memory and Recyclable Ionomeric Elastomer Composites with Renewable Lignin via Interfacial Metal-Ligand Interactions.

Lignin, the most abundant aromatic polymer in nature, is one of the most promising renewable feedstocks for value-added polymer products. However, it is challenging to prepare high-performance and multifunctional polymer materials with renewable lignin because of its poor compatibility with the elastomer matrix. In fact, lignin often requires solvent fractionation, chemical modification, or prohibitively expensive additives.

Reconfigurable scan lens based on an actively controlled optical phased array.

Integrated photonics provides a path for miniaturization of an optical system to a compact chip scale and offers reconfigurability by the integration of active components. Here we report a chip-scale reconfigurable scan lens based on an optical phased array, consisting of 30 actively controlled elements on the InP integrated photonic platform. By configuring the phase shifters, we show scanning of a nearly diffraction-limited focused spot with a full width at half maximum spot size down to 2.

Efficient four-wave mixing based on multiple plasmonic resonance.

Plasmonic nanostructures provide a new way to improve nonlinear optical effects. As a mode of surface plasmons (SP), localized SPs can highly localize and enhance electromagnetic fields within a subwavelength volume. In this work, we developed a one-dimensional V-groove Ag nanograting.

Tuning of Two-Dimensional Plasmon-Exciton Coupling in Full Parameter Space: A Polaritonic Non-Hermitian System.

Non-Hermitian photonic systems with gains and/or losses have recently emerged as a powerful approach for topology-protected optical transport and novel device applications. To date, most of these systems employ coupled optical systems of diffraction-limited dielectric waveguides or microcavities, which exchange energy spatially or temporally. Here, we introduce a diffraction-unlimited approach using a plasmon-exciton coupling (polariton) system with tunable plasmonic resonance (energy and line width) and coupling strength.

Modification of Electrospun Regenerate Cellulose Nanofiber Membrane via Atom Transfer Radical Polymerization (ATRP) Approach as Advanced Carrier for Laccase Immobilization.

This study aimed to modify an electrospun regenerated cellulose (RC) nanofiber membrane by surface grafting 2-(dimethylamino) ethyl methacrylate (DMAEMA) as a monomer via atom transfer radical polymerization (ATRP), as well as investigate the effects of ATRP conditions (i.e., initiation and polymerization) on enzyme immobilization.

Engineering Giant Rabi Splitting via Strong Coupling between Localized and Propagating Plasmon Modes on Metal Surface Lattices: Observation of Scaling Rule.

We present a strong coupling system realized by coupling the localized surface plasmon mode in individual silver nanogrooves and propagating surface plasmon modes launched by periodic nanogroove arrays with varied periodicities on a continuous silver medium. When the propagating modes are in resonance with the localized mode, we observe a √ scaling of Rabi splitting energy, where is the number of propagating modes coupled to the localized mode. Here, we confirm a giant Rabi splitting on the order of 450-660 meV ( = 2) in the visible spectral range, and the corresponding coupling strength is 160-235 meV.

A Performance-enhanced Electroosmotic Pump with Track-etched Polycarbonate Membrane by Allylhydridopolycarbosilane Coating.

Nanochannel plastic membranes are excellent materials for electroosmotic pump (EOP) elements owing to their surface charge properties, flexibility and cost-effectiveness. However, the surface charge properties of plastics are inferior to those of silicate-based materials. This paper reports a performance-enhanced EOP equipped with a glassified track-etch polycarbonate membrane (PC), which has a nanochannel surface covered by allylhydridopolycarbosilane (AHPCS).

Enhancement in speed and responsivity of uni-traveling carrier photodiodes with GaAsSb/InGaAs type-II hybrid absorbers.

We demonstrate a top-illuminated high-speed uni-traveling carrier photodiode (UTC-PD) with a novel design in the p-type absorber, which can effectively shorten the photon absorption depth at telecommunication wavelengths (1.31~1.55 μm) and further enhance the bandwidth-efficiency product of UTC-PD.

Bromo- or Methoxy-Group-Promoted Umpolung Electron Transfer Enabled, Visible-Light-Mediated Synthesis of 2-Substituted Indole-3-glyoxylates.

A visible-light-mediated radical tandem cyclization of ortho-isocyano-α-bromo cinnamates to 2-substituted indole-3-glyoxylates is achieved by formation of both C-C/C-S and C-O bonds. The reaction proceeds through a hitherto unprecedented bromine- or methoxy-group-promoted umpolung back electron transfer from an α-carbonyl radical to the photocatalyst. This method allows preparation of diverse 2-arylated or 2-thioarylated indole-3-glyoxylates.

Broadband Absorption Enhancement in Polymer Solar Cells Using Highly Efficient Plasmonic Heterostructured Nanocrystals.

Raising the light absorption of the photoactive layer in polymer solar cells (PSCs) without increasing the layer thickness is desirable but challenging because of the low carrier mobility of organic materials. Herein, we used the coupled localized surface plasmon resonance of heterostructured Au-CuS nanocrystals (NCs) to improve the light-trapping capability of the photoactive layer of PSCs. Broadband light absorption and a considerable improvement of the power conversion efficiency were obtained when the photoactive layer was doped with a tiny amount of NCs.

Fully integrated microwave frequency synthesizer on heterogeneous silicon-III/V.

We demonstrate a photonic microwave generator on the heterogeneous silicon-InP platform. Waveguide photodiodes with a 3 dB bandwidth of 65 GHz and 0.4 A/W responsivity are integrated with lasers that tune over 42 nm with less than 150 kHz linewidth.

Polymorphisms of 23 Y-chromosome STR Loci in A Han Population in Jiangsu Province.

Objective To investigate the polymorphisms of 23 Y-STR loci in a Han population in Jiangsu province. Methods Blood samples were collected from 4821 unrelated healthy Han males in Jiangsu province. DNA templates were amplified by PowerPlex Y23 kit,and the amplification products were detected by 3500xL genetic analyzer.

Monolithically integrated InAs/InGaAs quantum dot photodetectors on silicon substrates.

We report InAs/InGaAs quantum dot (QD) waveguide photodetectors (PD) monolithically grown on silicon substrates. A high-crystalline quality GaAs-on-Si template was achieved by aspect ratio trapping together with the combined effects of cyclic thermal annealing and strain-balancing layer stacks. An ultra-low dark current of 0.

Cascaded exciton energy transfer in a monolayer semiconductor lateral heterostructure assisted by surface plasmon polariton.

Atomically thin lateral heterostructures based on transition metal dichalcogenides have recently been demonstrated. In monolayer transition metal dichalcogenides, exciton energy transfer is typically limited to a short range (~1 μm), and additional losses may be incurred at the interfacial regions of a lateral heterostructure. To overcome these challenges, here we experimentally implement a planar metal-oxide-semiconductor structure by placing a WS/MoS monolayer heterostructure on top of an AlO-capped Ag single-crystalline plate.