Fabrication of Ge nano-dot heterojunction phototransistors for improved light detection at 1.55 mu m

Heterojunction phototransistors (HPTs) with several Ge/Si nano-dot layers as the absorption region are fabricated to obtain improved light detectivity at 1.55 mu m. The HPT detectors are of n-p-n type with ten layers of Ge(8ML)/Si(45nm) incorporated in the base-collector junction and are grown by an ultrahigh-vacuum chemical-vapor deposition system. The detectors are operated with normal incidence. Because of the good quality of the grown material and fabrication process, the dark current is only 0.71pA/mu m(2) under 5 V bias and the break-down voltage is over 20 V. Compared to the positive-intrinsic-negative (PIN) reference detector with the same absorption layer, the responsivity is improved over 17 times for normal incidence at 1.55 mu m.

High performance of 1.55 mu m DFB integrated with vertically tapered self-aligned spot-size converter

A new type of self-aligned spotsize converter (SSC) integrated 1.55 mum DFB lasers had been proposed in this article. The upper optical confinement layer and the butt-coupled tapered thickness waveguide were regrown simultaneously, which not only offered the separate optimization of the active region and the integrated SSC, but also reduced the difficulty of the butt-joint selective regrowth. The vertical and horizontal far field angles were 9degrees and 12degrees respectively, the 1- dB misalignment tolerance were both 3.6 and 3.4 mum. The directed coupling efficiency to tapered single mode fiber was 48%.

Room temperature 1.55 mu m emission from InAs quantum dots grown on (001)InP substrate by molecular beam epitaxy

Self-assembled InAs nanostructures on (0 0 1)InP substrate have been grown by molecular beam epitaxy (MBE) and evaluated by transmission electron microscopy (TEM) and photoluminescence (PL). It is found that the morphologies of InAs nanostructures depend strongly on the underlying alloy. Through introducing a lattice-matched underlying InAlGaAs layer on InAlAs buffer layer, the InAs quantum dots (QDs) can be much more uniform in size and great improvement in PL properties can be attained at the same time. In particular, 1.55 mu m luminescence at room temperature (RT) can be realized in InAs QDs deposited on (0 0 1)InP substrate with underlying InAlGaAs layer. (C) 2000 Published by Elsevier Science B.V. All rights reserved.

1.55微米应变层量子阱分布反馈（DFB）激光器

于G批量导入至Hzhangdi

1.55-mu m resonant cavity enhanced photodiode based on MBE grown Ge quantum dots

Self-assembly Ge quantum dots (QD) on Si and Si/Ge mutli-quantum-wells (MQW) are grown by MBE. The island size and island density was investigated by atomics force microscopy. Ten-layer and twenty-layer MQW were selected for photodiode device fabrication. In photoluminescence (PL), a broad peak around 1.55-mu m wavelength was observed with higher peak intensity for the 10-layer MQW which had less defects than the 20-layer sample. Resonant cavity enhanced (RCE) photodiodes were fabricated by bonding on a SOI wafer. Selected responsivity at 1.55 mu m was successfully demonstrated. (c) 2005 Elsevier B.V. All rights reserved.

1.55 mu m Ge islands resonant-cavity-enhanced narrowband detector

The high quality Ge islands material with 1.55 mu m photo-response grown on Sol substrate is reported. Due to the modulation of the cavity formed by the mirrors at the surface and the buried SiO2 interface, seven sharp and strong peaks with narrow linewidth are found. And a 1.55 mu m Ge islands resonant-cavity-enhanced (RCE) detector with narrowband was fabricated by a simple method. The bottom mirror was deposited in the hole formed by anisotropically etching, in a basic solution from the backside of the sample with the buried SiO2 layer in silicon-on-insulator substrate as the etch-stop layer. Reflectivity spectrum indicates that the mirror deposited in the hole has a reflectivity as high as 99% in the range of 1.2-1.65 mu m. The peak responsivity of the RCE detector at 1543.8 nm is 0.028 mA/W and a full width at half maximum of 5 nm is obtained. Compared with the conventional p-i-n photodetector, the responsivity of RCE detector has a nearly threefold enhancement.

On-Chip All-Optical Passive 3.55 Gbit/s NRZ-to-PRZ Format Conversion Using a High-Q Silicon-Based Microring Resonator

We report the experimental result of all-optical passive 3.55 Gbit/s non-return-to-zero (NRZ) to pseudo-return-to-zero (PRZ) format conversion using a high-quality-factor (Q-factor) silicon-based microring resonator notch filter on chip. The silicon-based microring resonator has 23800 Q-factor and 22 dB extinction ratio (ER), and the PRZ signals has about 108 ps width and 4.98 dB ER.

A High-Efficiency Fiber-to-Waveguide Coupler with Low Polarization Dependence Using a Diluted Waveguide in InP Substrate with a 1.55μm Wavelength

We propose a fiber-to-waveguide coupler for side-illuminated p-i-n photodiodes to obtain high responsivity and low polarization dependence that is grown on InP substrate and is suitable for surface hybrid integration in low cost modules. The fiber-to-waveguide coupler is based on a diluted waveguide,which is composed of ten periods of undoped 120nm InP/80nm InGaAsP （1.05μm bandgap） multiple layers. Using the semi-vectorial three dimensional beam propagation method （BPM） with the central difference scheme,the coupling efficiency of fiber-to-waveguide under different conditions is simulated and studied,and the optimized conditions for fiber-to-waveguide coupling are obtained. For TE-like and TM-like modes,the calculated maximum coupling efficiency is higher than 94% and 92% ,respectively. The calculated polarization dependence is less than 0. ldB,showing good polarization independence.

键合法制备硅基1.55μm InP-InGaAsP量子阱激光器

在硅基上成功地制备出了1．55μm InP-InGaAsP量子阱激光器．设计并生长了适合于键合的量子阱激光器结构材料，通过直接键合技术，将Si衬底与InP-InGaAsP外延片键合到一起．剥离去掉InP衬底后，在5～6μm的薄膜上制备出20μm条形边发射激光器．室温下，阈值电流160mA（电流密度为2．7kA／cm^2），功率可达10mW以上（在约350mA电流下），实现了1．55μm长波长边发射激光器与Si的集成．目前，该结果国际上还未见报道．

1．55μm低温生长GaAs谐振腔增强型探测器

利用低温（200℃）生长的GaAs材料作为吸收层制备了GaAs基1．55μm谐振腔增强型（RCE）光电探测器，对其光电特性进行了分析、研究．无光照0偏压下探测器暗电流为8．0×10^12A；光电流谱峰值波长1563nm；响应谱线半宽4nm，具有良好的波长选择性．

硅基1．55μm可调谐共振腔窄带光电探测器的研究

制作了一种低成本硅基1．55μm可调谐共振腔增强型探测器．首次获得硅基长波长可调谐共振腔探测器的窄带响应，共振峰量子效率达44%，峰值半高宽为12．5nm，调谐范围14．5nm，并且获得1．8GHz的高频响应．本制作工艺不复杂，成本低，有望用于工业生产．

1.55μm MOEMS可调谐光滤波器调谐性能模拟

建立了等效单层梁模型和一维集总模型,用经典力学理论和传输矩阵方法模拟了多层材料构成且具有四臂固支梁结构的1.55μm Si基MOEMS(Micro-Opto-Electro-Mechnical-Systems)可调谐滤波器的调谐特性.模拟调谐系数与实验结果吻合较好.

1.55μm Laser Diode Monolithically Integrated with Spot-Size Converter Using Conventional Process

A novel 1.55μm laser diode with spot-size converter is designed and fabricated using conventional photolithography and chemical wet etching process.For the laser diode,a ridge double-core structure is employed.For the spot-size converter,a buried ridge double-core structure is incorporated.The laterally tapered active core is designed and optically combined with the thin and wide passive core to control the size of mode.The laser diode threshold current is measured to be 40mA together with high slop efficiency of 0.35W/A.The beam divergence angles in the horizontal and vertical directions are as small as 14.89°×18.18°,respectively,resulting in low-coupling losses with a cleaved optical fiber (3dB loss).

Fabrication of 1.55μm Si-Based Resonant Cavity Enhanced Photodetectors

A novel bonding method using silicate gel as bonding medium is developed.High reflective SiO2/Si mirrors deposited on silicon substrates by e-beam deposition are bonded to the active layers at a low temperature of 350℃ without any special treatment on bonding surfaces.The reflectivities of the mirrors can be as high as 99.9%.A Si-based narrow band response InGaAs photodetector is successfully fabricated,with a quantum efficiency of 22.6% at the peak wavelength of 1.54μm,and a full width at half maximum of about 27nm.This method has a great potential for industry processes.