Record-setting light bending of one infrared ray in two directions

https://phys.org/news/2023-09-record-setting.html

"highest double refraction, 3X birefringence of barium titanium sulfide... a few more strontium atoms than expected caused crystal's much larger repeating structure... largest anisotropy measured in any optical material... with press of a button, tiny changes in atomic structure from bending, heating or passing current through it dynamically change refractive index along 1 direction of material... night vision, Lidar, chemical sensing, microscopy"