Enhanced spontaneous emission observed at one-dimensional photonic band edges

We recently reported experimental evidence for double enhancement of spontaneous emission due to increased photon density of states and small group velocity at photonic band-edge frequencies by observing angle-resolved emission and excitation spectra of photoluminescence [K. Kuroda et al., Opt. Express 17, 13168 (2009)]. The specimen we used was a one-dimensional photonic crystal composed of periodic multilayers of Ta2O5 and SiO2 with oxygen vacancies as light emitters. In the present study, we report on the lack of any excitation intensity dependence of the emission peak height and width, which excludes possibilities of nonlinear effects, the polarized emission spectra, and their comparison with theoretical calculations to further confirm our finding.