Photonic generation of frequency-decupled microwave signal based on cascaded Mach-Zehnder modulators

Abstract

In order to effectively solve the generation problem of high frequency microwave signal, a frequency-decupled signal generation system based on two cascade Mach-Zehnder modulators (MZMs) is proposed. The RF drive signal is modulated by the first MZM, by adjusting the bias voltage, it is biased at the minimum transmission point (MITP). The generated signal is partly sent to the photoelectric detector (PD1) to heterodyne the first-order sidebands. With an optical coupler, the generated first-order sidebands are also used as the optical source for the second modulation. The generated frequency-doubled signal is modulated by the second MZM which is biased at the maximum transmission point (MATP), then the fifth-order sidebands signal are separated by a fiber Bragg grating from the generated sidebands. With the EDFA and PD2, the generation of a frequency-decupled microwave signal is realized. The structure is also verified by experiments, a frequency-decupled signal from 15 to 27GHz is generated by the drive source signal which is tuned from 1.5 to 2.7GHz.