MODELLING AND SIMULATION OF P-I-N QUANTUM DOT SEMICONDUCTOR SATURABLE ABSORBER MIRRORS

Semiconductor saturable absorber mirror (SESAM) based on InAs quantum dot (QD) material is important in designing fast mode-locked laser devices. A self-consistent time-domain travelling-wave (TDTW) model for the simulation of self-assembled QD-SESAM is developed. The 1-D TDTW model takes into consideration the time-varying QD optical susceptibility, refractive index variation resulting from the intersubband free-carrier absorption, homogeneous and inhomogeneous broadening. The carrier concentration rate equations are considered simultaneously with the travelling wave model. The model is used to analyze the characteristics of 1.3-μm p-i-n QD InAs-GaAs SESAM. The field distribution resulting from the TDTW equations, in both the SESAM absorbing region and the distributed Bragg reflectors, is obtained and used in finding the device characteristics including the modulation depth and recovery dynamics. These characteristics are studied considering the effects of QD surface density, inhomogeneous broadening, the number of QD absorbing layers, and the applied reverse voltage. The obtained results, based on the assumed device parameters, are in good agreement, qualitatively, with the experimental results.