Abstract

Small optical mode size (≤2 μm) is essential for high-performance waveguide-based devices [1] and lasers on III-V semiconductors. High efficiency fiber coupling to small modes, however, requires additional mode-matching elements and submicron alignment tolerances,[2] resulting in costly packages and reliability concems. These problems can be alleviated by monolithically tapering small modes to larger dimensions at chip edges, for which several techniques have been proposed.[2-8] Selective epitaxy, in which locally enhanced epitaxial growth rates are achieved in regions adjacent to dielectric masks, is particularly attractive because of its process simplicity, which requires no epitaxial regrowth nor complicated etch procedures. While selectively grown tapers were previously suggested,[7, 8] actual spot-size tapering using this technique has not been reported. Here we describe selectively grown InGaAsP/lnP tapers with low-loss and threefold spot-size increase.

© 1992 Optical Society of America