Superior elasto-optic tetragonal SrTiO<sub>3</sub> films

Cutting-edge acousto-optic devices require optically transparent thin films, which possess a high index of refraction and large elasto-optic coefficients. For the wide near-infrared to ultraviolet spectral region, the mainstream technology employs lithium niobate crystals, which interferes with the vital demands of global sustainability. Here, we demonstrate unprecedented elasto-optic properties in thin films of sustainable and environmentally friendly strontium titanate [SrTiO3(STO)]. Compared to cubic STO, a nearly twofold increase in elasto-optic coefficients is achieved in epitaxial tetragonal STO films, which concurrently exhibit excellent transparency and a high index of refraction at wavelengths from 400 to 1700 nm. The room-temperature non-polar state is evidenced by the thermo-optical behavior of the films. The obtained enhancement is related to the tetragonal antiferrodistortive phase of STO. It is suggested that such films can form a platform for future sustainable acousto-optic materials.

Tyunina M., Nepomniashchaia N., Vetokhina V., Dejneka A.

A1 Journal article – refereed

M. Tyunina, N. Nepomniashchaia, V. Vetokhina, and A. Dejneka, "Superior elasto-optic tetragonal SrTiO3 films", APL Materials 9, 121108 (2021)