Fig. 1. (a) Three general approaches for fiber supercontinuum generation: all-fiber splice often used in commercial supercontinuum lasers (approach 1), commercial enclosed device with fiber end capping and mode expansion as an add-on nonlinear wavelength converter for a Ti:sapphire oscillator (approach 2), and mounted bare (PM) fiber for coherent fiber supercontinuum generation by an fs Yb:fiber laser (approach 3). PP-FCPA, pulse-picked fiber chirped pulse amplifier; BB, beam blocker; HWP, half-wave plate; PBS, polarizing beam splitter; M, mirror; FL, focusing lens; PCF, photonic crystal fiber; CL, collimating lens. (b) Three schemes of polarized coherent fiber supercontinuum generation under study with wavelength-dependent dispersion of photonic crystal fibers indicative of the restriction of supercontinuum generation to fiber normal dispersion regimes (top) with a cross-sectional image of photonic crystal fibers indicative of pitch and hole sizes (inset), and corresponding spectra of supercontinuum outputs (bottom). (c) Output spectra at different f but the same E for Scheme 3 (top) in comparison with input spectra of source laser (inset), and output spectra at different E but the same f for Scheme 3 (bottom) with cross-sectional images of the supercontinuum generating fiber (inset).

Fig. 2. (a) Schematics of FNWC and related optical components for fs biophotonics switchable between different microscopes (or applications) by fiber-optic telecommunication connection and disconnection. (b) FNWC output spectrum (1030-nm central wavelength without filtering the supercontinuum), pulse width, spatial mode/profile, and full width at half-maximum (FWHM) pulse width versus GDD position before and after 1-m Kagome hollow-core fiber (left), in compassion to FNWC output spectrum (1110-nm central wavelength from filtered supercontinuum), pulse width, spatial mode/profile, and FWHM pulse width versus GDD position before and after 1-m Kagome hollow-core fiber (right).

Fig. 3. FLIM-empowered eSLAM imaging of unlabeled live specimens by FNWC. Scale bar: 50μm. (a)–(g) Time-lapse intravital imaging of a surgically opened mouse skin flap at one instance, showing flowing blood cells in a blood vessel (cyan arrows) and periodic sarcomeres along muscle myofibrils (arrowhead) in raw SHG/THG data (a) which are blurred in DeepCAD-RT-denoised data with a better overall SNR (b) but recovered in UDVD-denoised data with a better overall SNR (c); the UDVD-denoised data (d) also reveal stromal cells (red arrows) and lipids (stars) barely visible in raw 2PAF/3PAF data (e), resulting in a composite four-color image with discernible blood cells at one instance (f) that can be compared with the similar image at a different instance (g) (see Video 3). (h) 2PAF lifetime (FLIM) image of ex vivo mouse kidney tissue over a 5×5 mosaic of fields of view (1mm2 total area) that shows the red-colored large-scale vasculature with a fluorescence lifetime of <0.6ns.