Photonic Generation of Dual-band Arbitrary Phase-coded Signal Immune to Periodic Power Fading

A novel scheme for photonic generating dual-band phase-coded microwave signals that immune to periodic power fading is proposed and experimentally verified. By properly setting the bias voltages of a dual-polarization quadrature phase shift-keying (DP-QPSK) modulator, the upper arm of DP-QPSK modulator can be equivalent to a phase modulator (PM). The coding signal is phase modulated on the optical carrier. The lower arm of DP-QPSK modulator is driven by two local oscillator (LO) signals to obtain ±2nd-order sidebands with suppressed carrier. The optical signal with the +2nd-order sidebands removed is injected into a photodiode (PD) through single mode fiber (SMF). After PD a dual-band phase-coded signal is generated. The generated signal can suppress periodic power fading and is suitable for remote antenna systems. The experimental results show that the 0.5 Gbps binary/quaternary phase-coded signals with carrier frequencies of 6 and 11 GHz can be generated from local oscillator signals of 2.5 GHz and 3 GHz, and are transmitted through 50 km SMF.