Experimental Study of VCSEL-Based Optical Frequency Comb Generators

In this letter, we explore the performance of an optical frequency comb generator (OFCG) sources based on vertical-cavity surface-emitting laser diodes. The direct gain switching (GS) technique, the indirect electro-optical (EO) technique, and a combination of both have been experimentally evaluated. We have observed that this later combination gives birth to an enhanced OFCG that offers a tunable improved comb in terms of frequency span, flatness, and coherence with respect to the sole EO approach, as it partly inherits the high-efficiency qualities of the GS-OFCG while offering a wider span.