Lasing properties of disk microcavity based on a circular Bragg reflector

The lasing properties of quantum well structures, where the cavity is defin ed in the plane of the wells by circular Bragg reflectors are investigated. Diffraction of the in-plane lasing modes into the vertical direction by th e circular distributed Bragg reflector (DBR) allows the simultaneous measur ement of near-field emission patterns and emission spectra, allowing unambi guous assignment of azimuthal quantum numbers to the lasing modes. The radi al quantum number is determined by fitting the lasing spectrum to theory. L asing is shown to occur in modes whose wave vector is mainly radial, confin ed by the circular DBR structure, rather than in whispering gallery type mo des which are mainly azimuthal. (C) 1999 American Institute of Physics. [S0 003-6951(99)01546-6].