Tunable Multi-Band Linear Frequency Modulated Waveforms Generation Based on Self-Subharmonic Modulating of Optically Injected Semiconductor Laser

A tunable multi-band linear frequency modulated microwave waveform generating system based on photonic approach is proposed and experimentally demonstrated. In this system, a semiconductor laser is optically injected in period-one oscillation state. The optical injection signal, modulated by the period-one signal via a photodetector, subharmonically modulates the laser, enhancing waveform stability. The modulated laser period is set as an integer multiple of cavity delay to approach Fourier domain mode-locking, simultaneously boosting signals across frequencies and times. The generated waveform can be tuned to generate either a unidirectional chirped or a bidirectional reciprocal chirped linear frequency modulated signal, and its center frequency and bandwidth can be easily adjusted.