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。

High speed and long wavelength photodetector is the key device for high-bit-rate optical fiber communication systems and optical networks that need wide frequency bandwidth and high external quantum efficiency simultaneously. It is well known that to increase the speed of PIN photodetector, the absorbing layer thickness should be reduced. The reduction of the absorbing layer thickness means a reduction in the quantum efficiency. So for conventional PIN photodetectors, there is a tradeoff between the quantum efficiency and the device frequency bandwidth through the absorbing layer thickness. One effective solution to this conflict is to use a resonant cavity enhanced (RCE) photodetector. In the RCE photodetector, the absorbing layer is put inside a Fabry-Perot cavity. This means a very thin absorbing layer thickness can be used to achieve a high quantum efficiency and wide frequency bandwidth. In this paper, analyses of light field distribution in the absorption layer of RCE photodetector based on practical design and manufacture are performed. The expression of light field distribution is used in the continuity equations to the frequency response of the RCE photodetector. The frequency response of long wavelength RCE photodetector is analyzed and calculated. The result of analyses and calculation is almost identical with the measuring result of the wide frequency bandwidth RCE photodetector manufactured. That device is an InP-based long wavelength resonant cavity enhanced photodetector with InP-Air gap reflectors and has 8 GHz frequency bandwidth and about 60% external quantum efficiency with the active area of 50 μm×50 μm.