Spontaneous Emission of Tb3+ Doped in TiO2 Inverse Opal

The opal templates were assembled by vertical deposition of silica spheres 410 nanometers in diameter. TiO2 precursor solution prepared with sol-gel was used to infiltrate into the voids of the opal templates. Then the opals and reference sample were calcined at 450 degrees C for 4 h in an air furnace. The Tb3+ doped TiO2 inverse opals were prepared by dropping cusuante solution and dried in air as sample A, and reference sample dropping with cusuante solution was denoted as sample B. Compared with the sample B, the photoluminescence from Tb3+ doped TiO2 inverse opal photonic crystal was suppressed at 540 nm and enhanced at 484 nm due to the presence of the photonic band gap. Either suppression or enhancement depends on the difference of photon density of states between emission band and the stop-band.