We present very compact, as short as 20 μm 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 ∼95%. The front mirror has a similar configuration, but consists of three periods with a lower reflectivity (∼80%) in order to allow output coupling. Lasing has been achieved from 20 μm long and 8 μm 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.
Bragg mirrors 1D photonic band gap microlaser photonic microstructures semiconductor laser ultrashort cavity