High-Power Microwave Generation Through Distributed Optical Amplification Into a Photodiode Array on an Open Indium Phosphide Platform

High power handling is crucial to the performance of microwave photonic systems. Taking a fabless research approach, the high-power performance of the photodiodes on an open indium phosphide photonic integration platform is characterized experimentally. For improved power handling two travelling wave structures are presented. Open-ended operation at reduced bandwidth penalty, but with a potential gain in output microwave power of 6 dB is considered, analysing the effect of aperiodic loading and stub reflections. The single photo diode is found to have 1-dB compression of 5 dBm with 20 mA and -8 dBm with 10 mA at 1 GHz and 30 GHz respectively. For a 4-branch distributed photodiode array these numbers are improved to 16 dBm with 58 mA and -1 dBm with 45 mA, again at 1 GHz and 30 GHz respectively. Further the power conversion efficiency of the photodiodes is improved almost by a factor of four from 2.8% to 10.6% at 1 GHz, and the effect of included amplification on the efficiency is analysed. The limitations of the design is analysed through comparison of simulations with measurements and a discussion of the possible improvements and scaling of the method is given.