Ultrashort in-plane semiconductor microlasers with high reflectivity microstructured mirrors

We present very compact, as short as 20 mum long, low-threshold in-plane semiconductor lasers operating at a wavelength of 980 nm, in which microstructured mirrors have been formed at both cavity ends by deep reactive ion etching (RIE). The back mirror consists of a seven-period third order Bragg reflector with a measured reflectivity of similar to 95%. The front mirror has a similar configuration, but consists of three periods with a lower reflectivity (similar to 80%) in order to allow output coupling. Lasing has been achieved from 20 mum long and 8 mum wide devices exhibiting a current threshold of 7 mA. These are among the shortest in-plane Fabry-Perot electrically pumped lasers demonstrated to date.

Design issues are discussed, along with experimental data from which values for the reflectivity of the mirrors are derived. State-of-the-art electron beam lithography (EBL) and high-aspect-ratio RIE have been used for device fabrication, while additional strategies are proposed for the further improvement of the device performance.