Strong enhancement of spontaneous emission in amorphous-silicon-nitride photonic crystal based coupled-microcavity structures

We investigated photoluminescence (PL) from one-dimensional photonic band g ap structures. The photonic crystals, a Fabry-Perot (FP) resonator and a co upled-microcavity (CMC) structure, were fabricated by using alternating hyd rogenated amorphous-silicon-nitride and hydrogenated amorphous-silicon-oxid e layers. It was observed that these structures strongly modify the PL spec tra from optically active amorphous-silicon-nitride thin films. Narrow-band and wide-band PL spectra were achieved in the FP microcavity and the CMC s tructure, respectively. The angle dependence of PL peak of the FP resonator was also investigated. We also observed that the spontaneous emission incr eased drastically at the coupled-cavity band edge of the CMC structure due to extremely low group velocity and long photon lifetime. The measurements agree well with the transfer-matrix method results and the prediction of th e tight-binding approximation.