Abstract

A novel approach to photonic generation of Microwave hybrid frequency/phase shift keying (FSK/PSK) signal is proposed and demonstrated. In the proposed method, an electrical signal with different direct currents for bit ‘0’ and bit ‘1’ is generated. The signal is fed into a Mach-Zehnder modulator which is biased at minimum and maximum transmission point corresponding to bit ‘0’ and bit ‘1’ respectively. Then the optical signals are fed into a Sagnac loop incorporating a fiber Bragg grating and modulated by a coding signal through a phase modulator. After photo-detection, a hybrid FSK/PSK signal can be obtained. Simulations are conducted to verify the proposed scheme. A hybrid FSK/PSK signal with frequency shift of 20/40GHz and phase shift of π is successfully demonstrated. The compression ratio of the generated FSK/PSK signal is 16, the main-to sidelobe ratio is 7.5 dB.

© 2018 The Author(s)