Finite-difference time-domain analysis of laser diodes integrated with tapered beam-expanders

Waveguide properties of laser diodes integrated with horizontally tapered beam-expanders are analyzed by the finite-difference time-domain method. The taper length dependence of the radiation loss and fiber-coupling efficiency are clarified. Lower loss and higher fiber-coupling efficiency are achieved in the exponentially tapered beam-expander compared with a linearly tapered one having an equivalent length.