Analysis of a double-heterostructure spatial-phase controller for diode-laser beam steering

A numerical method to obtain the variation of an electric field as a noneigenmode lightwave propagates in a waveguide is discussed. The method is basically a mode expansion of the field using a hypothetical oversized waveguide with a modified index distribution. The hypothetical guide has an additive index step at remote boundaries, so that it has many discrete eigenmodes and, at the same time, permits light to propagate in the same way as in the original waveguide. The beam-steering properties of a double-heterostructure carrier-injection-type spatial-phase controller is then analyzed using this method. Conditions on the deflector structure and on the input light for smooth beam steering are discussed on the basis of the analysis.<>