Simulation and analysis of 1.55μm quantum dot lasers designed for ultra-narrow spectral linewidth

Quantum dots (QDs) are well known as active materials with remarkable properties such as high differential gain, very low linewidth enhancement factor and low threshold current density. Using a comprehensive in-house developed laser simulator based on the traveling wave method, we investigate the limitations in terms of spectral purity of quantum dot based distributed feedback lasers (DFB) for use in high bit rate optical communications. Even though quantum dot based edge emitting lasers have demonstrated linewidths below the standard quantum well and bulk lasers, by optimization of the resonant cavity we further reduce the linewidth to below 20KHz while studying the resulting operating conditions.