Generation of tunable and broadband optical frequency comb based on gain-switching vertical-cavity surface emitting laser driven by square wave signal under optical injection

We have experimentally investigated the generation of tunable and broadband optical frequency comb (OFC) based on a gain-switching vertical-cavity surface emitting laser driven by a square wave signal under optical injection. During the experiment, the influences of modulation frequency f(m) and injection light wavelength lambda(i) on OFC performances are analyzed systematically. The experimental results indicate that under suitable operation parameters, an OFC with bandwidth of 77.0 GHz within 10 dB power variation and single sideband phase noise of -115.7 dBc/Hz @ 10 kHz can be generated. Also, during the modulation frequency range of 1.5 GHz - 2.8 GHz, broadband OFCs with bandwidth exceeding 70.0 GHz can be obtained based on the square-current modulated VCSEL under optical injection.