Directional laser emission from chaotic modes in quadrupole-deformed GaN microdisks

Summary form only given. Material properties as well as materials processing of GaN results in high laser thresholds. Circular microdisk GaAs and GaN lasers have lower thresholds and non-directional emission, because of the feedback from whispering-gallery modes (WGMs). Stadium-shaped microdisk quantum cascade lasers have greatly increased emission and directionality, because feedback is provided by the regular-orbit "bow tie" modes. We report the achievement of directional laser emission from quadrupolar-deformed-cavity GaN microdisks which have the same threshold as circular microdisks but with feedback provided by chaotic-orbit modes which eventually incident the disk-air interface at angles below the critical angle for total internal reflection.