Self-starting VCSEL-based optical frequency comb generator.

In this paper, we present the simulation and experimental results of the first closed-loop system based on a directly modulated VCSEL in a gain-switching condition to generate optical frequency combs (OFC). In order to simulate the self-starting VCSEL-based optical frequency comb generator (SVOFC), we applied an intrinsic parameter extraction process to a C-band VCSEL using laser rate equations, static and dynamic measurements, and equivalent circuit models. The widest (62 GHz) and flattest (0.8) simulated OFC is obtained when the repetition frequency f0 is 2.5 GHz. Implementation of the C-band SVOFC also shows that under constant electrical conditions, flatness higher than 0.85 and spectral widths of 50 GHz are obtained when f0 = 2.5 GHz. The lowest phase noise at 10 kHz from the extracted electrical carrier is -127 dBc/Hz and is obtained when the optical fiber length is 5 km and f0 = 1.25 GHz.