Lateral mode confinement in bent waveguide structures

Bent waveguides have been used for many years to provide lateral guiding in semiconductor lasers. Since the simple effective index method applied to the bent waveguide structure is at best an estimation, we have applied the beam propagation method and the finite difference method to this problem. Our preliminary findings qualitatively agree with the effective index predictions: for a uniform index central layer, guiding on the mesa is obtained if the thickness of the sidewall layer is sufficiently thin; otherwise, guiding on the sloped regions may occur, as reported recently for visible semiconductor lasers