Unidirectional Bistability in AlGaInAs Microring and Microdisk Semiconductor Lasers

We report on room-temperature continuous-wave operation and single-mode lasing of microdisk and microring lasers with radii as small as 7 mu m. The waveguide sidewall roughness was minimized by an optimized fabrication process using hydrogen silsesquioxane ebeam resist and Cl-2-CH3-H-2 inductively coupled plasma etching. The devices show unidirectional bistability between the counterpropagating modes for radii larger than 30 mu m and a strong hybrid output polarization for radii smaller than 15 mu m with a transverse-magnetic component of approximately 30%.