Multichannel Continuously Tunable Microwave Phase Shifter With Capability of Frequency Doubling

A photonic generation of tunable microwave phase shifter with capability of frequency doubling is proposed and experimentally demonstrated using optical spectral shaping technique. Our proposed configuration only consists of a phase modulator (PM), a programmable optical filter, and one photodetector (PD). The phase modulated optical signal is fed into the programmable optical filter, where two specific harmonic sidebands of the modulated signal are chosen in order to apply a tunable phase shift to one of the selected sidebands. After optical amplification and beating at the PD, a frequency doubling microwave signal with continuously tunable phase shifter from 0° to 360° is obtained with less than 2.5 dB power fluctuation over a frequency range from 20 GHz to 33 GHz. Moreover, simultaneous four-channel microwave signals with independent phase shift setting are achieved, due to that the proposed configuration is compatible with wavelength division multiplexing (WDM) operation.