A new technique for constructing multilayer dielectric mirrors is described that results in high reflectivities with only two or three dielectric layer pairs per mirror. These structures are obtained by selectively etching layered AlxGa1−xAs material grown by molecular beam epitaxy and then replacing the etched regions with acrylic resin or air. A thin optical cavity produced by this technique is demonstrated with mirror reflectivities near 96%. These techniques allow the fabrication of lasers, light‐emitting diodes, or optical switches with high contrast ratio mirrors on both sides of an optically active region in order to enhance output coupling, lower laser thresholds, and increase modulation rates.