Photonic generation of microwave hybrid frequency/phase shift keying signals based on a parallel structure

A photonic microwave hybrid frequency and phase shift keying (FPSK) signal generator is proposed and demonstrated. In the scheme, a parallel structure is constructed to functions as an optical sidebands selector, in which a single-drive Mach-Zehnder modulator (MZM) is placed in parallel with another MZM and a phase modulator (PM). After the parallel structure, a following PM is employed to realize phase modulation. The output signal of the PM is combined with a local oscillator at the receiver after 6-km fiber transmission, and then a hybrid FPSK signal can be obtained after photodetection. The feasibility of the proposed scheme is verified by simulation through a transmission test in a radio over fiber (ROF) system, and a hybrid FPSK signal with frequencies of 5/15 GHz and phase shift of 𝜋 is successfully generated. The scheme features the advantages of polarization independence and good frequency tunability since no polarization multiplexing devices or frequency-dependent devices are applied.