Photonic Generation of Multiform Microwave Frequency Shift Keying Signal

Abstract

A photonic approach to generate multiform microwave frequency shift keying (FSK) signal is proposed. In the scheme, a dual-polarization quadrature phase shift-keying (DP-QPSK) modulator along with a polarization controller (PC) is employed to generate two orthogonally polarized signals containing specific optical sidebands, and a following tunable filtering switch (TFS) serve as optical sidebands selector. From a theoretical analysis, when the modulators in the scheme are properly biased, we can obtain microwave FSK signal with frequency multiplication factors of 2/4 or microwave FSK signal with flexible tunable subcarrier frequencies. Simulations are conducted to verify the proposed scheme. 10/20GHz and 8/12GHz microwave FSK signals are successfully generated, and the frequency tunability is also demonstrated. In addition, the impact of the non-ideal parameters is analyzed, and the results show that the scheme has good immunity to the small parameters deviation (within 3º). The distinct advantage of our scheme is that we realize multiform microwave FSK signal generation based on a single system, which may find applications in high-frequency multifunction wireless communication system or radar system. INDEX TERMS Microwave photonics; Microwave signal generation; Frequency shift keying.