Optical and transport characteristics of Raman injection laser with enhanced Stokes emission

摘要

Detailed theoretical study and modeling of a Raman injection quantum cascade laser (RI-QCL) with modification of the structure for improved laser performance are presented. The band structure of RI-QCL utilizing techniques with material-dependent effective mass and band nonparabolicity is calculated by solving the Schrodinger Poisson equations self-consistently. With a combination of coherent transport and a simplified five-level rate equations model, we present a theory describing the Stark-effect rollover in QC lasers. This leads to a compact predictive model to analyze the output characteristics of a QC laser, such as the electric field-current (F-I), light-electric field (L-F), and light-current (L-I) curves. The excellent agreement of the experimental data with the simulated L-I characteristic confirms the validity of our new approach. Additionally, modifications of the original RI-QCL structure focus on improving the Stokes-Raman nonlinearity. The results show that the main characteristics of the modified design, including threshold current, external quantum efficiency, and output power for the pump and Stokes lasers, are improved in comparison with the reference design. (C) 2015 Optical Society of America