Flexible Frequency-Hopping Microwave Generation by Dynamic Control of Optically Injected Semiconductor Laser

Under proper optical injection, period-one (P1) dynamics of an optically injected semiconductor laser can be excited by undamping the relaxation resonance of the semiconductor through Hopf bifurcation. The output intensity would oscillate at a microwave frequency, i.e., the P1 frequency. After optical-to-electrical conversion, a microwave signal can be generated with its frequency determined by the detuning frequency and the injection strength. Therefore, it provides a convenient way to dynamically control the instantaneous frequency of the generated microwave signal by manipulating the injection strength. In this work, a flexible frequency-hopping (FH) microwave waveform generator by dynamic control of an optically injected semiconductor laser is proposed and demonstrated. The system has a compact structure, and the key device is a commercial semiconductor laser. The generated FH microwave waveform has a high degree of flexibility, i.e., the central frequency, bandwidth, sequence length, and frequency order can be easily adjusted. A proof-of-concept experiment is carried out. Wideband (>10 GHz) stepped linear and Costas sequence are successfully generated. Autoambiguity functions of the generated frequency-hopping sequences are also investigated. The experimental results can verify the feasibility of the proposed FH waveform generator, which may find wide applications in future radar and communications systems.