Self-starting VCSEL-based optical frequency comb generator

Abstract

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.