Multiplexed nonlinear label-free microscopy by excitation engineering

SWIR-based microscopy has opened up windows to cellular and extracellular dynamics in deep tissues and living biological systems. New generation of laser sources, with high pulse energy, wide continuous tunable range, and a compact form, are in high demand to advance nonlinear microscopy and SWIR-based imaging to its full potential for deep-tissue imaging. This talk will discuss our recently developed approach that exploits the spatial and temporal degrees of control of nonlinear effects in step-index MMFs using a 3D-printed programmable fiber piano. By leveraging the rich spatiotemporal degrees of freedom and the high spectral brilliance in SI MMF, We have achieved broadband high-peak-power spanning 560–2200 nm, resulting from combined spectral energy reallocation (up to 166-fold) and temporal shortening (up to 4-fold) uniquely enabled by the fiber shaper. Its potential as a nonlinear imaging source is further demonstrated by applying the MMF source to multiphoton microscopy, where multi-fold signal enhancement is achieved for label-free tissue imaging with adaptive optimization.