Numerical Study of the Single Mode Stability of Quantum Well and Quantum Dot DFB Laser Diodes Under External Optical Feedback

Abstract

We numerically analysed the single mode stability of of multi quantum well and quantum dot DFB laser diodes in the presence of external optical feedback. Laser diodes which operate in a stable single mode in the absence of feedback were found to sometimes become multimode for external feedback levels below −30 dB. This is even the case for lasers with zero linewidth enhancement factor, even though such lasers are sometimes touted as feedback insensitive. The behavior depends strongly on the phase of the external reflection, as well as on the specific DFB laser structure.

Keywords

• DFB laser diode
• single mode stability
• feedback sensitivity
• quantum dot
• quantum well