Analysis of pulse amplification characteristics in vertical cavity semiconductor optical amplifiers

摘要

Based on the transfer matrix method (TMM), a comprehensive dynamic numerical model describing the optical pulse amplification in vertical cavity semiconductor optical amplifiers (VCSOAs) is established, which treats the whole VCSOA as one multilayer dielectric structure, including the two Distributed Bragg Reflectors (DBRs) and the middle active region. In this model, the spatial dependence of the carriers and optical field in the longitudinal direction and the discontinuity of refractive index distribution in the resonant cavity are accounted for. Moreover, in this study the influence of the two photon absorption (TWP) is also taken into consideration. By employing this model, we investigate the signal distortion and the pulse energy gain characteristic in single pulse amplification of VCSOAs operated in reflection mode in detail. The numerical results show that the pulse distortion can be mitigated in a satisfactory manner via reducing the period of top DBR. It further shows that the energy gain during the pulse amplification can be increased by enhancing the pump power; larger saturation input pulse energy (SIPE) could be obtained by either lowering the period of top DBR or reducing the pump power; for the input pulse with duration ranging from several to tens of picoseconds, the energy gain characteristics of VCSOA is pulsewidth independent.