Laser micromachining of tapered optical fibers for spatially selective control of neural activity.

Tapered and micro-structured optical fibers (TFs) recently emerged as a versatile tool to obtain dynamically addressable light delivery for optogenetic control of neural activity in the mammalian brain. Small apertures along a metal-coated and low-angle taper allow for controlling light delivery sites in the neural tissue by acting on the coupling angle of the light launched into the fiber. However, their realization is typically based on focused ion beam (FIB) milling, a high-resolution but time-consuming technique. In this work we describe a laser micromachining approach to pattern TFs edge in a faster, more versatile and cost-effective fashion. A four-axis piezoelectric stage is implemented to move and rotate the fiber during processing to realize micropatterns all-around the taper, enabling for complex light emission geometries with TFs.