In this work, broadband optical frequency comb (OFC) generation by a gain-switching vertical-cavity surface-emitting laser (VCSEL) subject to optical injection is investigated experimentally. During implementing the experiment, a 1550 nm VCSEL under a large signal current modulation is driven into the gain-switching state with a broad noisy spectrum. By further introducing an optical injection, a high performance OFC can be produced. The experimental results demonstrate that the power and wavelength of the injection light seriously affect the performance of the produced OFC. Under proper optical injection parameters, two sub-combs originating from two orthogonal polarization components of the VCSEL can splice into a broadband total-OFC. By selecting optimized operation parameters, a high quality total-OFC can be acquired, with stable comb lines, high coherence, wide bandwidth of 70.0 GHz (56.0 GHz) within 10 dB (3 dB) amplitude variation and low single sideband phase noise at the fundamental frequency below −120.6 dBc/Hz @ 10 kHz.
Power efficient optical frequency comb generation using laser gain switching and dual-drive Mach-Zehnder modulator
