Bound Modes in Dielectric Microcavities
  We demonstrate how exactly bound cavity modes can be realized in dielectric structures other than 3d photonic crystals. For a microcavity consisting of crossed anisotropic layers, we derive the cavity resonance frequencies, and spontaneous emission rates. For a dielectric structure with dissipative loss and central layer with gain, the beta factor of direct spontaneous emission into a cavity mode and the laser threshold is calculated. 
P.M. Visser, K. Allaart and D. Lenstra