Carrier diffusion effect in tapered semiconductor-laser amplifier

This paper proposes a theoretical model to study the beam amplification and the influence of the lateral drift and diffusion on the tapered semiconductor-laser amplifier in great detail. The overall effect of the lateral drift and diffusion could be represented by an effective diffusion coefficient. The analysis, which treats the effective diffusion coefficient as a controllable parameter, shows that both the beam quality and optoelectrical property can be improved using a large effective diffusion coefficient. The analysis also indicates that the effective diffusion in the separate-confinement heterostructure layer could affect the beam quality in the quantum-well amplifiers. In addition, the thermal effect on the device performance is studied and its influence is found to be extremely significant for the high-diffusion cases.