Hexagonal Prism Blue Laser Diode with Low Threshold Power using Whispering Gallery Mode (WGM) Resonances

In this work, electrically pumped room temperature emitters using hexagonal prism cavities have been fabricated. The hexagonal prism shape provides a route to atomically smooth facets through selective growth or post etching annealing treatments, exploiting the natural crystal form of the wurtzite-structured nitride heterostructures. The lasing mode of the hexagonal prism diodes was verified as WGM by using focused ion beam (FIB) to notch one of the hexagon facets. The threshold current density and forward voltage of the hexagonal prism laser diode were 7kA/cm2 and 9V, respectively. WGM and TIR are believed to be the main mechanisms for reduced reflection losses and increased overall resonance efficiency.