Figure 2.

Spatially selective light delivery using high-NA TF. (a) Diagram of the optical setup used for mode division demultiplexing (L1, L2, L3 lenses; GM galvanometric mirror). Laser light enters the fiber patch cord at an angle and is out-coupled from the taper surface immersed in fluorescein. A sCMOS camera acquires fluorescence images of the light emission. The GM motion is synchronized with the camera acquisition via custom software (see Methods). (b) Left, emission images for a NA = 0.66, 200 µm core size fiber with increasing input angle. Scale bars are 250 µm. Center, diagram of the tapered section. The blue line indicates the profile along which the intensity was measured. Right, intensity profiles measured at different input angles with respect to the distance from the tip. Four selected regions are selected by varying the input angle. (c) Position of the intensity centroid of the emission region (blue circles) and positions of the FWHM values of the emission region (pale blue dots) with respect to the input angle for a NA = 0.66 TF. The red line indicates a linear fit performed on the centroid position. Ray tracing simulations results are displayed as black diamonds, with a linear fit shown as a black dashed line. (d) As in panel (c) for a NA = 0.39 TFs. (e) Far field images of the patch cord injected with θ = 10°, 20° at 473 nm. Scale bars are 0.15∙2π/λ. (f) Top, centroid and boundaries of the injected k_t-subset versus input angle. Bottom, centroid position versus the injected k_t for 0.66 NA, orange line, and 0.39 NA, dashed blue line.