Spatiotemporal beam self-cleaning for high-resolution nonlinear fluorescence imaging with multimode fiber.

Area of Science:

• Optics and Photonics
• Biomedical Imaging
• Materials Science

Background:

• Beam self-cleaning (BSC) in graded-index (GRIN) multimode fibers (MMFs) is a phenomenon driven by Kerr effect and self-imaging.
• BSC counteracts random mode coupling, restoring a quasi-single mode profile at the fiber output.
• This effect has implications for improving light delivery through MMFs.

Purpose of the Study:

• To investigate the impact of BSC on nonlinear fluorescence (NF) microscopy and endoscopy.
• To demonstrate the enhancement of imaging performance through spatiotemporal reshaping induced by BSC.
• To explore the utility of BSC for high-resolution biological imaging.

Main Methods:

• Experimental demonstration of BSC in GRIN MMFs.
• Utilizing self-induced spatiotemporal reshaping for nonlinear imaging.
• Performing two- and three-photon fluorescence imaging of biological samples.
• Employing spatiotemporal supercontinuum (SC) generation for broad-band NF imaging.

Main Results:

• Self-cleaning increases beam brightness, enabling high-resolution two- and three-photon imaging.
• Temporal pulse shortening enhances output peak power, boosting nonlinear imaging efficiency.
• Spatiotemporal SC generation facilitates large-band NF imaging in visible and infrared spectra.
• Successful multiphoton fluorescence imaging in both microscopy and endoscopy configurations.

Conclusions:

• BSC in GRIN MMFs significantly improves nonlinear fluorescence microscopy and endoscopy performance.
• The enhanced beam quality and peak power facilitate high-resolution and efficient biological imaging.
• BSC offers a promising approach for advanced optical imaging techniques using multimode fibers.