Antiguiding index profiles in broad strip semiconductor lasers for high-power, single-mode operation

Solutions to the wave equations for a one-dimensional quadratic variation in the complex refractive index profile are used to calculate gain and field distributions for the lateral modes of broad-stripe semiconductor lasers. It is found that a large difference in gain between the fundamental mode and higher-order modes is obtained in profiles with strong real-index antiguiding and weak imaginary-index guiding. The effect of truncating the quadratic profile is explored. A criterion for comparing the tendency for single-mode operation in different index profiles is introduced and applied to quadratic, step, and array profiles. Based on the analysis, device structures for achieving high-power, single-mode operation are proposed.>