Abstract

We describe the fabrication and operation of a novel GaAlAs "tapered" waveguide antenna for use at GaAs laser wavelengths (λ_o=0.86 μm). This antenna is tapered in the sense that the confinement of the guided mode is reduced near the sample endface both by physically reducing the waveguide dimension and, more importantly, by reducing the refractive index difference between the waveguide film and cladding along the length of the guide. In preliminary measurements this antenna is shown to produce a ~60% increase in the near-field effective mode width at the cleaved endface of a single-mode GaAlAs slab waveguide, resulting in a ~40% reduction in the far-field output beam divergence.

© 1989 Optical Society of America