Evaluation of InGaAs/InP photodiode for high-speed operation at 4 K

An optically controlled high-speed current source located at 4 K is likely to improve the performance of pulse-driven Josephson junction arrays. A custom photodiode module with an Albis PDCS24L InGaAs/InP PIN photodiode is investigated in order to determine the suitability at 4 K. The DC and frequency response were tested at room temperature and at temperatures down to 4 K. For continuous wave optical input, photocurrents above 15 mA were produced at both room temperature and 4 K. I –V measurements show that the threshold voltage increased from 0.5 V at room temperature to 0.8 V at 4 K. The transmission coefficient S21 of the optoelectronic system, including cables and modulated laser source, was measured using a vector network analyzer. Up to 14 GHz, the results showed that the frequency response at 4 K was not degraded compared to room temperature. At room temperature, reverse bias voltages of up to 3 V was required for the highest bandwidth, while at 4 K, the photodiode was operated at nearly full speed even at 0 V reverse bias.