Edge-emitting InGaAs/GaAs lasers with deeply etched semiconductor/air distributed Bragg reflector mirrors

The fabrication and properties of 18 mum wide, 200 mum long edge-emitting InGaAs/GaAs lasers with a distributed Bragg reflector (DBR) mirror at one cavity end and a cleaved facet at the other are presented. The three-period third-order DBRs with high aspect ratio (similar to14: 1) and nearly vertical sidewalls have been fabricated by reactive ion etching. The device threshold current and maximum output power are 30 mA and 80 mW, respectively. The spectral width of the lasing line is only 2 nm. The reflectivity of the DBR, determined by comparing the differential efficiencies from the DBR and the cleaved facet, is 73%. The width of the far-field pattern from the DBR end in the parallel direction (12degrees) is slightly larger than that from the cleaved facet (8degrees). By contrast, the width of the far-field pattern from the DBR end in the perpendicular direction is only 8degrees, which is five times smaller than that from the cleaved facet.