Analysis of mode behavior in a waveguide with graded index and gain

Numerical analysis has been carried out for a waveguide with graded index and gain. It is shown that the radiation peak of the fundamental mode is deflected as the gradient of either the index or gain increases. The high-order modes also change their peak intensity ratio as the gradient of index or gain increases. The behavior of the fundamental mode is suitable for use in a beam scanner while that of higher-order modes is suitable for use in a deflection switching of laser beams. The analysis also shows that the modal gain of higher-order modes becomes larger than that of the fundamental mode as the gradient of the index and gain increases, which provides some explanation for the wide laser beam scanning observed by Scifres et al.