Optimal Photodetector Size for High-Speed Free-Space Optics Receivers

TL;DR

This paper derives a method to optimize photodetector size in free-space optical communication systems to maximize data rates by balancing bandwidth and signal power.

Contribution

It provides a closed-form solution for selecting the optimal photodetector area to maximize channel capacity across various optical wireless scenarios.

Findings

Optimal photodetector size enhances channel capacity.

Closed-form solutions applicable to diverse optical communication systems.

Trade-off analysis between bandwidth and signal power.

Abstract

The selection of an optimal photodetector area is closely linked to the attainment of higher data rates in optical wireless communication receivers. If the photodetector area is too large, the channel capacity degrades due to lower modulation bandwidth of the detector. A smaller photodetector maximizes the bandwidth, but minimizes the captured signal power and the subsequent signal-to-noise ratio. Therein lies an opportunity in this trade-off to maximize the channel rate by choosing the optimal photodetector area. In this study, we have optimized the photodetector area in order to maximize the channel capacity of a free-space optical link for a diverse set of communication scenarios. We believe that the study in this paper in general -- and the closed-form solutions derived in this study in particular -- will be helpful to maximize achievable data rates of a wide gamut of optical wireless communication systems: from long range deep space optical links to short range indoor visible light communication systems.