We study the performance scaling laws for electrical-domain combining in photodetector (PD) array-based receivers employing intensity modulation and direct detection, taking into account the inherent square-law relationship between the optical and electrical received powers. The performance of PD array-based systems is compared, in terms of signal-to-noise ratio (SNR) and achievable rate, to that of a reference receiver employing a single PD. Analytical and numerical results show that PD arrays provide performance gains for sufficiently narrow beams and above an SNR threshold. Furthermore, increasing the number of PDs alone does not enhance performance, and joint optimization of beam pattern, transverse electromagnetic mode, received power, and PD positions is necessary. Our model and derived insights provide practical guidelines and highlight the trade-offs for the design of next-generation high-bandwidth PD array receivers.

翻译：本文研究了采用强度调制与直接检测的光电探测器（PD）阵列接收机中电域合并的性能缩放规律，并考虑了光接收功率与电接收功率之间固有的平方律关系。我们从信噪比（SNR）和可达速率两方面，将基于PD阵列的系统性能与采用单个PD的参考接收机进行了比较。分析与数值结果表明，对于足够窄的光束以及在超过某一SNR阈值后，PD阵列能够带来性能增益。此外，仅增加PD数量并不能提升性能，必须对光束模式、横电磁模式、接收功率以及PD位置进行联合优化。我们的模型及所推导的结论为设计下一代高带宽PD阵列接收机提供了实用指导，并揭示了其中的设计权衡。