We report experimental studies of the bending strain impact on the upconversion processes in Yb3+, Er3+, and Mn2+ co-doped BaTiO3 (BTO) thin films with mica as the flexible substrate. Bending strain induces strong enhancement and modulation of the upconversion emission in doped BTO thin films. Because the unshielded 3d5 configuration of Mn2+ is more susceptible to crystal field changes, the introduction of an Mn2+ ion further promotes the strain-induced modulation effect. The upconversion intensity is amplified by six times at bending strain ε = 1.83% in BTO:Yb3+/Er3+/Mn2+ thin films. These results demonstrate the opportunity of rendering an upconversion emission through integrating lanthanide-doped ferroelectric films with flexible mica, especially by incorporating an Mn2+ ion.

We describe a Si-integrated photochromic photomemory based on lanthanide-doped ferroelectric Na0.5Bi2.5Nb2O9:Er3+ (NBN:Er) thin films. We show that upconversion emission can be effectively modulated by up to 78% through the photochromic reaction. The coupling between lanthanide upconversion emission and the photochromic effect ensures rewritable and nondestructive readout characteristics. Moreover, integrating photochromic thin films with Si would benefit from its compatibility with the mature complementary metal-oxide semiconductor (CMOS) technique. These results demonstrate the opportunity to develop more compact photochromic photomemories and related photonic devices.