Photonic Generation of Multiform Microwave Frequency Shift Keying Signal

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 3°). 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.