Multiple frequency measurement based on self-oscillating and subharmonic modulating of optically injected semiconductor laser

A multiple microwave frequency measurement system based on Fourier domain mode-locked self-oscillating and subharmonic modulating of an optically injected semiconductor laser is proposed. In this system, the microwave signal to be tested is modulated onto the sweeping optically injected signal, which lock the semiconductor laser in period-one oscillation state, completing a wide bandwidth and frequency fast tunable microwave photonic filter system. The time delay of self-oscillating cavity is an integral multiple of the frequency sweeping period of the optically injected signal to achieve the system operating in a Fourier domain mode-locked state, which enhances the stability of the generated period-one state signal. The signal to be tested oscillates in the system and beats with the generated signal to form pulses through a narrow bandpass filter completing the high-precision frequency-to-time mapping relationship. The feasibility of this system is discussed from theoretical perspectives and the frequency detected capability of this system is also tested in this paper. Ultimately, a stable multifrequency measurement system is achieved with an average frequency detected accuracy of around 8 MHz.