Tunable ferroelectric photonic crystals based on Ba_(0.7)Sr_(0.3)TiO_3/MgO multilayer thin films

摘要

It is of interest to the optoelectronic community if index-tunable photonic crystals can be realized by using ferroelectric materials since the refractive index of ferroelectric materials can be electrically tuned through the electro-optic effect. In this paper, we present our work on developing a tunable one-dimensional (1D) photonic crystal (PC) based on a Ba_(0.7)Sr_(0.3)TiO_3/MgO multilayer structure. A ferroelectric 1D photonic crystal consisting of a Ba_(0.7)Sr_(0.3)TiO_3/MgO multilayer thin film was epitaxially deposited on a MgO (001) single-crystal substrate by pulsed laser deposition. A photonic band gap in the visible region is observed in the transmission spectrum of the multilayer thin film. The centre wavelength of the band gap is ～ 464 nm, which agrees with the simulation result obtained by the transfer matrix method. The band gap can be tuned by an external electric field E. The band gap shifts about 2 nm under a dc voltage of 240 V (E ～ 12 MV/m).