Focusing supercontinuum laser through multimode optical fibers beyond the fiber facet: Overcoming challenges with ps-pulsed sources

Wavefront shaping has been recently enabling imaging of neural activity in deep brain regions by employing ultra-thin endoscopes based on multimode optical fibers, exploiting the wealth of information that can be carried by thousands of modes in a core diameter as small as 50 μm. However, applying this technique to pulsed laser sources still represents a challenge due to the intrinsic delay and temporal broadening introduced by the fiber itself, which requires additional compensation optics on the reference beam during the calibration procedure. In this presentation, we will describe our approach to combine a picosecond-pulsed supercontinuum laser and an internal reference to produce a focused spot scanning in multiple planes at the output of a step-index multimode fiber, without the requirement of a delay line.