Influence of graded index waveguides on the gain difference between TEO and TMO modes of semiconductor optical amplifiers

摘要

Polarization independent semiconductor optical amplifiers are highly desirable for optical communication. In this paper, the influence of graded index waveguides on the gain difference between TE$-0$/ and TM$-0$/ modes of semiconductor optical amplifiers is studied in detail. A new numerical procedure called complex shooting method was proposed at first to solve the eigenvalues of waveguides with graded complex refractive index. The results show that a graded index waveguide will increase the polarization sensitivity of the modal gain while an unplanar waveguide can decrease it. A polarization independent semiconductor optical amplifier can be obtained by adopting an unplanar waveguide.