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.

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.

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.

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.

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.

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.

Forward bias operation of silicon photonic Mach Zehnder modulators for RF applications.

In this paper, we demonstrate that forward bias (+0.9V) of a high-speed silicon (Si) optical Mach-Zehnder modulator (MZM) increases the radio-frequency (RF) link gain by 30 dB when compared to reverse bias operation (-8V). RF applications require tunable, narrowband electro-optic conversion with high gain to mitigate noise of the optical receiver and realize high RF spur-free dynamic range.

[Arginase Level in Apheresis Leukocyte-Reduced Platelets Stored for Different Time].

Objective: To explore the effect of storage time on arginase level and possible source of arginase in apheresis leukocyte-reduced platelets(ALR-Plt).

Methods: The arginase level and myeloperoxidase(MPO) levels in ALR-Plt and control plasma were detected by ELISA. The relationship between arginase level and MPO level in ALR-Plt was analyzed by correlation analysis.

N(2)-Selective Iodofunctionalization of Olefins with NH-1,2,3-Triazoles to provide N(2)-Alkyl-Substituted 1,2,3-Triazoles.

A new method was developed to synthesize N(2)-alkyl-substituted 1,2,3-triazole through N-iodosuccinimide (NIS) mediated iodofuctionalization reaction of the alkene group with bi-, mono-, and unsubstituted NH-1,2,3-triazoles. The favored N-1 type hydrogen bond between the iodonium ion intermediate and 1,2,3-triazole was supposed to be generated, which gave the desired N(2)-alkyl triazole with a high N(2)-selectivity.

NHC-Ag(I)-Catalyzed Three-Component 1,3-Dipolar Cycloaddition To Provide Polysubstituted Dihydro-/Tetrahydrofurans.

A new method was developed to synthesize polyfunctionalized dihydrofuran and tetrahydrofuran derivatives from the three-component [2 + 2 + 1] cycloaddition of the diazoesters with aryl/alkenyl aldehydes and alkyne/olefin dipolarophiles by using a Ag(I) N-heterocyclic carbene complex as the catalyst. A carbonyl ylide intermediate was generated, which undertook an endo-type 1,3-dipolar cycloaddition to provide the desired dihydro-/tetrahydrofurans in high regio- and diastereoselectivities by using α-aryl or α-alkenyl diazoesters.

[Arginase Level in Suspended Red Blood Cells Storaged for Different Time].

Objective: To explore the effect of storage time on arginase level, and the possible source of arginase in suspended red blood cells (RBC).

Methods: The arginase and myeloperoxidase (MPO) levels in suspended RBC and control plasma were detected by ELISA. The free hemoglobin level in suspended RBC and control plasma were detected by colorimetric method.

[Impact of Toxoplasma gondii infection on pregnancy outcomes in early pregnant women].

Objective: To explore the impact of Toxoplasma gondii infection on pregnancy outcomes in early pregnancy women.

Methods: Toxoplasma gondii IgM and IgG antibodies in the peripheral blood of 2 993 early pregnant women were detected by using enzyme-linked immunosorbent assay (ELISA). According to the test results, the infected ones were divided into an acute infection group, a previous infection group, and an active infection group, and 200 pregnant women without Toxoplasma infection were randomly chosen as a control group, and the pregnancy outcomes of the four groups were followed up and the results were compared.

[Efficiency of three methods for detecting Toxoplasma IgG antibody].

Objective: To discuss the test efficiency of three methods for detecting Toxoplasma IgG antibody.

Methods: Totally 304 specimens were detected parallelly for Toxoplasma IgG antibody by using the gold marked method, indirect hemagglutination test (IHA), and enzyme-linked immunosorbent assay (ELISA), and the sensitivity, specificity and Youden index of these methods were compared.

Results: The detection sensitivities of gold marked method, IHA, and ELISA for Toxoplasma IgG antibody were 85.

Photonic chirped radio-frequency generator with ultra-fast sweeping rate and ultra-wide sweeping range.

A high-performance photonic sweeping-frequency (chirped) radio-frequency (RF) generator has been demonstrated. By use of a novel wavelength sweeping distributed-feedback (DFB) laser, which is operated based on the linewidth enhancement effect, a fixed wavelength narrow-linewidth DFB laser, and a wideband (dc to 50 GHz) photodiode module for the hetero-dyne beating RF signal generation, a very clear chirped RF waveform can be captured by a fast real-time scope. A very-high frequency sweeping rate (10.

Design and demonstration of ultra-fast W-band photonic transmitter-mixer and detectors for 25 Gbits/sec error-free wireless linking.

A 25 Gbits/s error-free on-off-keying (OOK) wireless link between an ultra high-speed W-band photonic transmitter-mixer (PTM) and a fast W-band envelope detector is demonstrated. At the transmission end, the high-speed PTM is developed with an active near-ballistic uni-traveling carrier photodiode (NBUTC-PD) integrated with broadband front-end circuitry via the flip-chip bonding technique. Compared to our previous work, the wireless data rate is significantly increased through the improvement on the bandwidth of the front-end circuitry together with the reduction of the intermediate-frequency (IF) driving voltage of the active NBUTC-PD.

Compact and passive-alignment 4-channel x 2.5-Gbps optical interconnect modules based on silicon optical benches with 45 degrees micro-reflectors.

Compact and passive-alignment 4-channel x 2.5-Gbps optical interconnect modules are developed based on the silicon optical benches (SiOBs) of 5 x 5 mm2. A silicon-based 45 degrees micro-reflector and V-groove arrays are fabricated on the SiOB using anisotropic wet etching.

Transverse-junction superluminescent diodes at the 1.1 microm wavelength regime.

We demonstrate, for the first time to our knowledge, GaAs-based transverse-junction (TJ) superluminescent diodes (SLDs) that operate at a wavelength of 1.1 microm. Due to lateral current injection by use of TJ, specified as transverse carrier flow spread in each quantum well horizontally instead of vertical well-by-well injection, nonuniform carrier distribution can be minimized among different multiple quantum wells (MQWs), which is a problem in vertical-junction (VJ) SLDs whose electroluminescent (EL) spectrum is governed by the center wavelength of QWs near the p side.

Spatial manipulation of nanoacoustic waves with nanoscale spot sizes.

Coherent acoustic phonons are generated at terahertz frequencies when semiconductor quantum-well nanostructures are illuminated by femtosecond laser pulses. These phonons-also known as nanoacoustic waves-typically have wavelengths of tens of nanometres, which could prove useful in applications such as non-invasive ultrasonic imaging and sound amplification by the stimulated emission of radiation. However, optical diffraction effects mean that the nanoacoustic waves are produced with spot sizes on the micrometre scale.