Increased photon density of states at defect-mode frequencies led enhancement of tunability of spontaneous emission from Eu2+, 3+ doped SiO2/SnO2 one-dimensional photonic crystals

One-dimensional photonic crystal (1DPhC) micro-cavity resonators, constituted of Eu-2+,Eu- 3+ doped silica layer inserted between two 5-bilayered SiO2/SnO2 Bragg mirrors, are fabricated by sol-gel process. The 1DPhC exhibits a similar to 180 nm wide stop-band, with peak-reflectivity of more than 96%. Spectral modifications of the photonic stop-band by varying the angle of detection with respect to the sample surface normal are studied. With an increase in the detection angle from 0 degrees to 45 degrees the defect-mode continuously sweeps from 598.6 nmto 532.0 nm, selectively enhancing the coinciding Eu-2+,Eu- 3+ emission. To quantify the increase in spontaneous emission at defect-mode frequencies, a relative enhancement factor is devised. The increased photon density of states at defect-mode frequencies is found to enhance the weak emission tail of Eu-2+,Eu- 3+ ions by a factor of similar to 9.