GaAs micro-pyramids serving as optical micro-cavities

An efficient light‐matter coupling requires high‐quality (Q) micro‐cavities with small mode volume. We suggest GaAs micro‐pyramids placed on top of AlAs/GaAs distributed Bragg reflectors to be promising candidates. The pyramids were fabricated by molecular‐beam epitaxy, electron‐beam lithography and a subsequent wet‐chemical etching process using a sacrificial AlAs layer. Measured Q‐factors of optical modes in single pyramids reach values up to 650. A finite‐difference time‐domain simulation assuming a simplified cone‐shaped geometry suggests possible Q‐factors up to 3600. To enhance the light confinement in the micro‐pyramids we intend to overgrow the pyramidal facets with a Bragg mirror—results of preliminary tests are given.