Study on fiber coupling of high-speed and high-power MUTC-PD in packaging

The distribution of the incident optical field has a significant impact on the performance of high-speed, high-power photodiodes, affecting parameters such as output power and bandwidth. In this paper, based on the theory of Gaussian beam propagation and transformation, we analyze the influence of the optical fiber coupling distance on the distribution of the incident optical field in the photodiode. We investigate how different coupling distances and various output optical powers affect the photodiode's radiofrequency (RF) output power, bandwidth, and responsivity. We determine an optimized coupling distance range for different output optical powers, under which the device can simultaneously achieve high RF output power and a wide bandwidth.