Motion-less depth-selective optogenetic probe using tapered fiber and an electrically tuneable liquid crystal steering element.

A miniature electrically tuneable liquid crystal component is used to steer light from -1° to +1° and then to inject into a simple tapered fiber. This allows the generation of various propagation modes, their leakage, and selective illumination of the surrounding medium at different depth levels without using mechanical movements nor deformation. The performance of the device is characterized in a reference fluorescence medium (Rhodamine 6G) as well as in a mouse brain (medullary reticular formation and mesencephalic locomotor regions) during in-vivo experiments as a proof of concept. This device may be further miniaturized to be applied to freely behaving animals for the dynamic selective excitation or inhibition of different brain regions.