Generation of Wideband Optical Frequency Comb With Coincident Polarization Based on Gain- Switched Vertical-Cavity Surface-Emitting Laser Under Orthogonal Optical Injection

A system framework of wideband optical frequency comb (OFC) with coincident polarization is numerically analyzed based on a gain-switched vertical-cavity surface-emitting laser (VCSEL) subject to orthogonal optical injection. In the structure, the VCSEL is driven by a current modulation with a sinusoidal signal. Then, by introducing an optical injection, two orthogonal and wideband OFCs are obtained. Further adding a polarizer, a wideband overall OFC with coincident polarization can be produced. The simulated results show that the intensity of the injected field and the frequency detuning of the injection light play an important role in the performance of the overall OFC. Through selecting the suitable operating parameters, a high-quality overall OFC with coincident polarization can be achieved, which includes 21 comb lines within 10 dB peak variation, and the according bandwidth achieves 122.2 GHz, the carrier-to-noise ratio is about 42.65 dB.