Toward the application of 400 G optical receiver chips in optical communication systems, this paper presents a $1\times 4$ photodetector (PD) array with a monolithic integrated InP microlenses structure. The absorption layer of the PD array in question includes the non-depleted, partially depleted, and depleted regions. This third-order composite absorber layer accelerates the diffusion of electrons in the absorber layer and balances the transport times of holes and electrons. Therefore, the high-speed and high responsivity characteristics of the device can be realized. The integration of InP microlenses on the backside of the PD allows the effective photosensitive surface area to be increased and the incident light alignment deviation to be compensated. Tests yielded a 3-dB bandwidth of the PD array at 1310 nm greater than 40 GHz, with a peak responsivity of 0.64 A/W. The responsivity of two types of PDs was measured when incident at a distance of $10~\mu \text{m}$ away from the main optical axis. The responsivity of the integrated microlenses decreased to 67.05% of the maximum value. Compared to the device without integrated microlenses, the responsivity increased by 66.76%.

中文翻译：

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用于光通信传输的 1 × 4 集成微透镜高速光电探测器阵列

针对400G光接收芯片在光通信系统中的应用，本文提出了一种 $1\乘以4$具有单片集成 InP 微透镜结构的光电探测器 (PD) 阵列。所讨论的 PD 阵列的吸收层包括非耗尽区、部分耗尽区和耗尽区。该三阶复合吸收层加速了电子在吸收层中的扩散并平衡了空穴和电子的传输时间。因此，可以实现器件的高速和高响应度特性。在PD背面集成InP微透镜可以增加有效感光表面积并补偿入射光对准偏差。测试结果表明，PD 阵列在 1310 nm 处的带宽高于 40 GHz，峰值响应率为 0.64 A/W。两种类型的 PD 的响应度是在入射距离为 $10~\mu \text{m}$远离主光轴。集成微透镜的响应度下降至最大值的67.05%。与没有集成微透镜的设备相比，响应度提高了66.76%。