The Tunable Phase Shift of High-Speed PIN Photodetector and Modified Uni-Traveling Carrier Photodetector

We report the phase shift of two types of photodetectors for a variation of bias voltage and optical power. One type is PIN-PD and the other is a modified uni-traveling carrier photodetector (MUTC-PD). In PIN-PD, the phase change shows a photocurrent-dependent variation of about 15 degrees at 3 GHz. It exhibits good stability over a wide bandwidth as the bias voltage changes. By comparison, the phase shift of the MUTC-PD is more sensitive to the bias voltage and the photocurrent. The continuous tunable range of phase shift in MUTC-PD reaches 50 degrees at 10 GHz. It is demonstrated that the adjustable phase shift mainly results from the transit time and the impedance dynamic effects in response to the optical power and bias voltage.