Spatiotemporal focusing through a multimode fiber via time-domain wavefront shaping

We shape fs optical pulses and deliver them in a single spatial mode to the input of a multimode fiber. The pulse is shaped in time such that at the output of the multimode fiber an ultrashort pulse appears at a predefined focus. Our result shows how to raster scan an ultrashort pulse at the output of a stiff piece of square-core step-index multimode fiber and in this way show the potential for making a nonlinear fluorescent image of the scene behind the fiber, while the connection to the multimode fiber can be established via a thin and flexible single-mode fiber. The experimental results match our numerical simulation well. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

This study demonstrates how to perform nonlinear fluorescent imaging behind a multimode fiber using femtosecond optical pulses, with a connection established to the multimode fiber via a single-mode fiber. The experimental results are in good agreement with numerical simulations.