Three-dimensional-ordered Yb/Er co-doped Bi<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub> inverse opal, powder, and disordered reference samples are prepared and their upconversion (UC) emission properties and mechanisms are investigated. Significant suppression of UC emission is detected when the photonic band-gaps overlap with Er<sup>3+</sup> UC green emission bands. Interestingly, green and red UC emissions follow a two-photon process in the powder sample but a three-photon one in the inverse opal.
© 2013 Chinese Optics Letters
Dong Yan, Zhengwen Yang, Jiayan Liao, Hangjun Wu, Jianbei Qiu, Zhiguo Song, Dacheng Zhou, Yong Yang, and Zhaoyi Ying, "Investigation of the mechanism of upconversion luminescence in Er3+/Yb3+ co-doped Bi2Ti2O7 inverse opal," Chin. Opt. Lett. 11, 041602- (2013)