Tunable optics using phase transitions in rare-earth nickelates

Rare-earth nickelates (RNiO3) are promising materials for tunable optics over a broad wavelength range from the visible to the mid infrared, due to their reversible phase transitions. I will present our work on the characterization of optical properties of rare-earth nickelates SmNiO3 and NdNiO3 across their phase transitions. First, I will discuss the thermally driven transition of SmNiO3, which we have used to demonstrate temperature-independent thermal radiation in the mid infrared. Then, I will discuss our recent results, demonstrating control of the optical properties of NdNiO3 using electron doping via lithium-ion intercalation, which takes the material from a nearly metallic state to an insulating transparent state with a large band gap of 3-4 eV. NdNiO3 has promise as an electrically driven tunable material which has low loss in at least one of its states, and we believe it may be possible to switch this material between two low-loss states with substantially different refractive index. We aim to establish this material as a platform for electrically tunable photonic devices operating from visible to mid-infrared wavelengths.