All-optical multi-octave microwave phase shifter

Abstract

In wideband multi-octave phase-shifting photonic links, second-order distortions (SDs) overlap with fundamental signals and cannot be filtered out. In this paper, we propose an all-optical microwave phase shifter, which suppresses the SDs and supports the amplitude tuning of the fundamental signals. The proposed all-optical phase shifter is based on polarization modulation and differential detection. Thanks to the all-optical techniques, maximum operating frequency of the proposed phase shifter is not limited by electronic bottlenecks. By using polarization modulation, the phase and amplitude of the output fundamental signals are tuned by simply manipulating the polarization states of the optical signals. By using differential detection, SDs components with same frequencies cancel out each other. Simulation results show that phase shift of 360° and power adjustable extent over 21.41 dB for the output fundamental signals are achieved. The direct current (DC) and the SDs components are well suppressed after differential detection. The typical spurious free dynamic range (SFDR) is significant improved by 21.79 dB from 77.78 dB·Hz1/2 to 99.57 dB·Hz2/3.