Design of Novel Photodetector Array in Optical Communication Systems and Optimization of Signal Processing Algorithm

Abstract

This study aims to enhance the high-speed and high-power performance of photodetectors, focusing on the epitaxial layer structure of photodetector arrays. The epitaxial structure of the photodetector involves a P–I–N structure with InAlAs/InGaAs heterostructures. InAlAs is used as the P-region material, and a dual-waveguide photodetector array is designed with a core diameter of 20 μm. The optical coupling is achieved through normal incident vertical illumination. Additionally, a novel structure of a dual-core symmetrically connected photodetector array is proposed, altering the electrode structure and core arrangement to maintain consistent distances for the output signals from the cores to the device’s output terminal. In order to address the issue of minimum bit error rate in optical communication systems under conditions of optical noise and limited energy efficiency of received optical signals, a photodetector array signal processing algorithm is proposed. The experimentally designed dual-core symmetrically connected P–I–N photodetector array achieves a 3 dB bandwidth of 15.37 GHz at an average photocurrent of 5 mA. Furthermore, it maintains a 3 dB bandwidth of 11.67 GHz at a high-power operating state of 50 mA, with an alternating current (AC) saturation current of 56 mA and a saturated RF output power of 1.11 dBm at 11.67 GHz. In comparison, the improved dual-core traveling-wave photodetector array at 11.67 GHz only achieves an AC saturation current of 38 mA and a saturated RF output power of 2.66 dBm. The signal processing algorithm for the selected dual-core symmetrically connected P–I–N photodetector array demonstrates that employing a method of merging array elements reduces the system’s computational complexity with minimal impact on the system’s power consumption.