High-Reflectivity Semiconductor/Benzocyclobutene Bragg Reflector Mirrors for GaInAsP/InP Lasers

Abstract

Fabrication techniques of high-reflectivity deeply etched semiconductor/benzocyclobutene (BCB) Bragg reflectors by multiple sequential steps of CH4/H2 reactive ion etching (RIE) and O2 plasma ashing are presented. 1.55-µm-wavelength GaInAsP/InP lasers with such reflectors exhibited low threshold current and high differential quantum efficiency with high uniformity. Threshold current as low as 7.2 mA and differential quantum efficiency as high as 50% from the front cleaved facet were obtained for a laser with a 160-µm-long active region and 15 distributed Bragg reflectors (DBRs) on the rear side. The reflectivity of the 15 DBRs was estimated to be as high as 95% from the threshold current dependence on the active region length. Finally, a preliminary aging test under room temperature CW conditions showed stable operation for more than 5000 h.