Optical properties of asymmetric photonic crystals

Transmission and photoluminescence spectra are investigated in periodic waveguides of tris(8-hydroxyquinoline) aluminum (Alq3) with asymmetric profile. Spontaneous emission pattern was found to be asymmetric due to the asymmetric coupling between the guided-wave mode and the radiation modes. The samples are fabricated by evaporating Alq3 obliquely to quartz grating substrate and can be regarded as one-dimensional asymmetric photonic crystals.