Characteristics of the Frequency-Locked States Generated by a Semiconductor Laser under Periodical Optical Injection and Their Applications in Frequency Conversion

Characteristics of the frequency-locked states generated by nonlinear dynamical behaviors of semiconductor lasers under periodical optical injection are investigated experimentally. The periodic optical waveforms used for injection, including repetitive pulses and sine oscillations, are generated from a laser (master laser) through self optoelectronic feedback and direct current modulation, respectively. Under proper operational conditions, namely the repetition frequency and injection strength of the injected light, microwave frequency combs are observed at the output of the injected laser (slave laser). In generating the microwave frequency combs, the pulse injection scheme shows the best performance compared to the sine modulation and cw optical injection schemes. The potential applications of these microwave frequency combs in frequency division and multiplexing are demonstrated.