Reconfigurable photonic dual‐frequency phase‐coded signals generator by using optical carrier phase shifting and polarisation selection

Abstract

A novel photonic dual-frequency phase-coded signals generator based on the optical carrier phase shifting and polarisation selection techniques is proposed by using an integrated dual-polarisation quadrature phase shift keying (DP-QPSK) modulator. The key feature of the scheme is the capability to generate dual-frequency phase-coded signals with reconfigurable frequency multiplication factors. In the upper QPSK modulator, an optical binary phase shift keying (BPSK) signal and a carrier-suppressed double-sideband optical signal are generated, while in the bottom QPSK modulator, another carrier-suppressed double-sideband optical signal is generated. Thanks to the dual-polarisation property of the integrated modulator, the optical BPSK signal and different optical sidebands can be selected by using polarisation selection. As a result, two phase-coded signals with different frequencies can be achieved simultaneously. By adjusting the bias phases of the submodulators, dual-frequency phase-coded signals with frequencies of one and three, or two and four times the frequency of the RF carrier can be generated. The generation of 2.5 Gbps dual-frequency phase-coded signals with frequencies of 20 and 40 GHz, or 10 and 30 GHz are verified. The proposed scheme is simple, compact, and promising to find applications in future multi-band and multi-functional radars.