谐振腔增强型光探测器的高速响应性能研究

高速长波长光探测器是高速光纤通信系统和网络的关键器件，它要求光探测器具有宽的频率响应带宽和高量子效率。常用的PIN光探测器由于量子效率和高速性能均受到吸收层厚度的牵制，使得二者相互制约，成为一对矛盾。谐振腔增强型(RCE)光探测器为这一矛盾的解决提供了有效的方案。基于谐振腔增强型光探测器的实际设计和制作模型，分析了器件吸收层中的光场分布，并将其运用于载流子的连续方程，从理论上详细地分析了器件的高速响应特性，给出了计算结果。针对研制的高速长波长谐振腔增强型光探测器，进行了理论分析和实际器件测试的结果比较，得到了比较一致的结果。     

Design of resonant-cavity-enhanced photodetectors using geneticalgorithms

Expressions of quantum efficiency of resonant-cavity-enhanced (RCE) PIN photodetectors reported in the literature are based on the assumption of constant reflectivities of the quarter-wave stacks (QWS) at the ends of the cavity. The quantum efficiency is formulated in a closed analytical form that includes the structural parameters of the photodetector and takes into account the wavelength dependence of the reflectivities and the active region absorption coefficient. The variation of the QWS reflectivity and, in particular, its phase constant with wavelength has a significant influence on the resulting quantum efficiency spectra, as demonstrated in this paper. The results are in very good agreement with recently published experimental data which show a dominant peak at the operating wavelength. This behavior has not been predicted by previous simulation results. Since the quantum efficiency spectra are not periodic, the use of the finesse, defined as the ratio of the free spectral range to the full width at half maximum, as a measure of wavelength selectivity is not valid. The conventional quality factor definition used for filter design is thus adopted as a measure of selectivity. A genetic algorithm-based optimization and design procedure for RCE photodetectors have also been developed with the quantum efficiency, quality factor, and frequency bandwidth as input design parameters     

Design and optimization of high-speed resonant cavity enhancedSchottky photodiodes

Resonant cavity enhanced (RCE) photodiodes (PD's) are promising candidates for applications in optical communications and interconnects where high-speed high-efficiency photodetection is desirable. In RCE structures, the electrical properties of the photodetector remain mostly unchanged; however, the presence of the microcavity causes wavelength selectivity accompanied by a drastic increase of the optical field at the resonant wavelengths. The enhanced optical field allows to maintain a high efficiency for faster transit-time limited PD's with thinner absorption regions. The combination of an RCE detection scheme with Schottky PD's allows for the fabrication of high-performance photodetectors with relatively simple material structures and fabrication processes. In top-illuminated RCE Schottky PD's, a semitransparent Schottky contact can also serve as the top reflector of the resonant cavity. We present theoretical and experimental results on spectral and high-speed properties of GaAs-AlAs-InGaAs RCE Schottky PD's designed for 900-nm wavelength     

新型三腔谐振腔增强型光探测器的理论分析和数值模拟

提出了一种新的谐振腔增强型 (RCE)光探测器结构 ,它将器件结构中的谐振腔分为三个子腔。分析表明 ,采用这种新结构的光探测器在保留了 RCE光探测器优点的同时 ,还实现了器件量子效率及其光谱响应线宽之间制约关系的解耦 ,因而可以同时获得窄的光谱响应线宽 (<1 nm) ,高的量子效率 (>90 % )和高的响应速度。该器件可望在密集波分复用 (DWDM)光通信系统中得到广泛应用     

特殊图案透明欧姆接触微结构提高谐振腔增强型光探测器的响应性能

为解决谐振腔增强型(RCE)光探测器的耦合效率和响应速率的矛盾,提出了采用特殊图案透明欧姆接触的微结构及其制备工艺方案,从而使得在器件入光面积不变的情况下,欧姆接触部分的总面积显著减小,在不影响器件量子效率的前提下达到减小电容、提高响应速率的目的。在台面面积为50μm×50μm的情况下,获得了18 GHz的响应带宽。研制的谐振腔增强型光探测器的响应速率得到了显著的提高。     

A novel resonant cavity enhanced photodetector with flat-top and steep-edge response

A novel resonant cavity enhanced (RCE) photodetector with flat-top and steep-edge response is presented. The response is obtained by designing a gradient-thickness P area in the absorption cavity. Simulation results show that the maximum and minimum values of the quantum efficiency in bandpass are 85.242% and 87.564% respectively, the ripple is about 3.6%, and 0.5 dB, 3 dB and 20 dB bandwidths are 0.3 nm, 0.4 nm and 1.2 nm, respectively. The mesa area is 10 μm × 10 μm and the frequency response bandwidth is 87 GHz. Compared with similar photodetectors, this photodetector has high quantum efficiency, narrow spectral response linewidth, good flat-top and steep-edge response and ideal high-speed characteristics.     

High quantum efficiency and narrow absorption bandwidth of thewafer-fused resonant In0.53Ga0.47As photodetectors

We demonstrate greater than 90% quantum efficiency in an In_0.53Ga_0.47As photodetector with a thin (900 Å) absorbing layer. This was achieved by inserting the In_0.53 Ga_0.47As/InP epitaxial layer into a microcavity composed of a GaAs/AlAs quarter-wavelength stack (QWS) and a Si/SiO₂ dielectric mirror. The 900-Å-thick In_0.53 Ga_0.47As layer was wafer fused to a GaAs/AlAs mirror, having nearly 100% power reflectivity. A Si/SiO₂ dielectric mirror was subsequently deposited onto the wafer-fused photodiode to form an asymmetric Fabry-Perot cavity. The external quantum efficiency and absorption bandwidth for the wafer-fused RCE photodiodes were measured to be 94±3% and 14 nm, respectively. To our knowledge, these wafer-fused RCE photodetectors have the highest external quantum efficiency and narrowest absorption bandwidth ever reported on the long-wavelength resonant-cavity-enhanced photodetectors     

Design and analysis of resonant cavity enhanced-waveguide photodetectors for microwave photonics applications

New structures for high quantum efficiency, high speed, and wavelength-selective photodetectors (PDs) are proposed. Regarding the main advantages of both resonant-cavity-enhanced (RCE) PDs and waveguide PDs (WGPDs) and the use of resonant behavior of microring waveguides, we present RCE-WGPD. The fundamental equation for quantum efficiency of microring PDs is derived and the important features of the device such as improvement of efficiency and wavelength selectivity are discussed.     

Modeling and performance of wafer-fused resonant-cavity enhancedphotodetectors

We discuss wavelength tuning and its corresponding quantum efficiency modulated by the standing wave effects in a resonant-cavity enhanced (RCE) photodetector. Specific design conditions are made for a thin In_0.53Ga_0.47As (900 Å) photodetector wafer-fused to a GaAs-AlAs quarter wavelength stacks (QWS). Analytic expressions for the calculation of resonant wavelength and standing wave effects are derived, using a hard mirror concept of fixed phase upon reflection, and are found to agree reasonably well with the exact numerical approach, using a transmission matrix method. We then experimentally demonstrate that wavelength tuning as large as 140 nm and its corresponding quantum efficiency modulated by the standing wave effects are clearly observed in our wafer-fused photodetectors, consistent with the predictions. The external quantum efficiency at 1.3 μm wavelength and absorption bandwidth for the wafer-fused RCE photodiodes integrated with an amorphous Si-SiO₂ dielectric mirror are measured to be 94% and 14 nm, respectively. This technique allows the formation of multichannel photodetectors with high quantum efficiency and small crosstalk, suitable for application to wavelength demultiplexing and high-speed, high-sensitivity optical communication systems     

高速长波长谐振腔增强型光探测器的瞬态性能研究

基于谐振腔增强型(RCE)光探测器的实际设计和制作模型,提出了综合器件的隔离层及器件的串联电阻、结电容等参数的高速长波长RCE光探测器的瞬态响应特性的表达式,包括器件的冲击响应、阶跃响应和脉冲响应.从理论上详细地研究了高速长波长RCE光探测器的瞬态响应特性,最后给出了不同器件结构参数的计算结果.     

Transient simulation of heterojunction photodiodes-part II:analysis of resonant cavity enhanced photodetectors

The high-speed response properties of resonant cavity enhanced (RCE) photodetectors have been investigated. The limitations on the high-speed performance of photodiodes and the advantages of RCE-detection are discussed. Transient response of heterojunction photodiodes under pulsed optical illumination has been simulated using the method described in Part I. Results on conventional AlGaAs/GaAs and RCE GaAs/InGaAs heterojunction p-i-n photodiodes are presented. For small area detectors, almost 50% bandwidth improvement along with a two-fold increase in efficiency is predicted for RCE devices over optimized conventional photodiodes. A nearly three-fold enhancement in the bandwidth-efficiency product was shown     

Optimization procedure for the design of ultrafast, highlyefficient and selective resonant cavity enhanced Schottky photodiodes

An expression of quantum efficiency for high-speed resonant-cavity-enhanced (RCE) Schottky photodiodes is derived. This expression includes the structural and the physical parameters of the photodetector and takes into account the parameters of the metallic Schottky mirror and the wavelength dependence of the reflectivities. The metal layer thickness sets the maximum achievable quantum efficiency as it decays exponentially with it. The antireflection coating layer, on the other hand, determines the photodetector selectivity and the optimum absorption layer thickness that maximizes its quantum efficiency. An algorithm for the design and optimization of RCE Schottky photodetectors has been developed. Theoretical values of 647 GHz and 129 GHz were obtained, respectively, for the carrier-transit time limited 3-dB bandwidth and bandwidth-efficiency product for an RCE Schottky photodetector with a 0.02 μm gold layer     

GaAs基量子阱谐振腔增强型光电探测器特性研究

通过对谐振腔增强型（RCE）光电探测器的理论分析和实验测试结果，证明对应不同光束入射角度， RCE光电探测器的模式波长按一定规律可调谐. 并给出当入射角度变化10°～60° ，模式调谐范围约为40nm，而谐振波长处的量子效率峰值及半高宽FWHM的变化与材料吸收系数紧密相关.     

A GaAs-Based MOEMS Tunable RCE Photodetector with Single Cantilever Beam

A GaAs-based micro-opto-electro-mechanical-systems(MOEMS) tunable resonant cavity enhanced(RCE) photodetector with a continuous tuning range of 31nm under a 6V tuning voltage is demonstrated.The single cantilever beam structure is adopted for this MOEMS tunable RCE photodetector.The maximum and minimum peak quantum efficiency during the tuning are 36.9% and 30.8%，respectively.The maximum and minimum full-widthathalf-maximum (FWHM) are 20nm and 14nm，respectively.The dark current density is 7.46A/m2 without bias.     

单悬臂梁结构的GaAs基MOEMS可调谐RCE光探测器

成功研制了GaAs基MOEMS可调谐RCE光探测器.该器件采用单悬臂梁结构,在6V的小调谐电压下,获得了31nm的连续调谐范围.在调谐过程中,峰值量子效率最大为36.9%,最小为30.8%;FWHM最大为20nm,最小为14nm.在0V偏压下器件的暗电流密度为7.46A/m2.     

Resonant-Cavity-Enhanced Far-Infrared Upconversion Imaging Devices

We have carried out a detailed investigation on the application of resonant cavities to the photon-frequency-upconversion-based far-infrared (FIR) semiconductor imaging devices. The employment of a bottom mirror (BM) enhances the FIR photon absorption efficiency and, therefore, increases the quantum efficiency of GaAs homojunction interfacial work- function internal photoemission (HIWIP) FIR detectors. Significant improvement of the extraction efficiency could be achieved in resonant cavity enhanced (RCE) GaAs-AlGaAs near-infrared (NIR) light-emitting diodes (LEDs) through redirecting as many NIR photons as possible into the escape cone. Under the optimal structural parameters, we have predicted that the upconversion quantum efficiency of the integrated HIWIP-BM-RCE-LED imaging device could be boosted to 5-6 times of the normal HIWIP-LED upconverter without any resonant cavities. As a consequence of few reincarnation cycles needed by NIR photons to escape in the photon recycling process, we can further expect sharp and high-resolution imaging in HIWIP-BM-RCE-LED     

Design of ultra-fast dual-wavelength resonant-cavity-enhancedSchottky photodetectors

A systematic optimization procedure for the design of RCE Schottky photodetectors to achieve maximum quantum efficiency and high speed operation at 1.3 and 1.55 μm wavelengths is presented. The quantum efficiency formulation used includes the structural parameters of the photodetector and takes into account the wavelength dependence of the top and bottom mirrors reflectivities. The results have shown that the value of the thickness of the antireflection coating layer has a major influence in selecting the width of the photodetector to simultaneously achieve maximum quantum efficiency and high bandwidth at the two wavelengths. Simulated values of 270 and 40 GHz were obtained, respectively, for the 3-dB carrier-transit time-limited bandwidth and bandwidth-efficiency product for an RCE Schottky photodetector with a 0.02-μm gold layer     

RCE光电探测器顶部DBR的优化

对研制的VCSEL结构外延片制成的谐振腔增强型（简称RCE）光电探测器进行了物理分析和实验研究,由于VCSEL与RCE光电探测器对谐振腔反射镜的反射率要求不同,通过腐蚀VCSEL器件顶部DBR,改变顶镜反射率,能够得到量子效率峰值和半宽优化兼容的RCE光电探测器,实现VCSEL与RCE探测器的单片集成．     

一种具有平顶陡边响应的新型谐振腔增强型(RCE)光电探测器的理论分析及模拟

提出了一种适用于波分复用系统的具有平顶陡边响应的新型谐振腔增强型 (RCE)光电探测器结构 ,模拟得到了量子效率从峰值下降 0 5dB的线宽 1 8nm ,10dB的线宽 5 6nm ,2 0dB的线宽 10 4nm ,量子效率峰值99 7%,几乎没有凹陷的响应曲线。     

新型长波长InP基谐振腔增强型光探测器

介绍了一种新型长波长InP基谐振腔增强型(RCE)光探测器。通过V(FeCl3):V(H2O)溶液对InGaAs牺牲层的选择性湿法腐蚀,制备出具有InP/空气隙的高反射率分布布拉格反射镜(DBR),并将该选择性湿法腐蚀技术成功地应用到长波长InP基谐振腔增强型光探测器的制备中去,从而彻底解决了InP/InGaAsP高反射率分布布拉格反射镜难以外延生长的问题。所制备出的谐振腔增强型光探测器,其台面面积为50μm×50μm,底部反射镜为1.5对的InP/空气隙分布布拉格反射镜,顶部反射镜靠InGaAsP与空气的界面反射来实现。测试结果表明,该谐振腔增强型光探测器在波长1.510μm处获得了约59％的峰值量子效率,在3V反偏压下暗电流为2nA,3dB响应带宽达到8GHz。