High-Power Highly Linear Photodiodes for High Dynamic Range

July 10, 2017
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High power, highly linear photodiodes enhance the overall dynamic range of LADAR systems in two ways: faithfully transferring optical return signal into RF domain with high coherent gain and minimal non-linear distortions, and generating low-phase photonic microwave clocks. Large power handling capability of the photodiodes also reduces the requirement of signal amplification by RF amplifiers, which further improves the dynamic range. We present a 10 GHz bandwidth InGaAs p-i-n photodiode that generates broadband linear RF signal with peak-to-peak output amplitude up to 4 V and power-to-phase conversion factor <4 rad/W. The photodiode’s performance is reported with pulsed stimulus, for repetition rates varying from 1 GHz to 10 GHz, as well as continuous wave signals. At higher power levels, these photodiodes produce compressed signals up to 6 V peak-to-peak output. In the compressed regime the power-to-phase conversion factor approaches zero for selected operating conditions, which is useful for generating precision clocks.