Challenges and Prospects of Using Novel Nonlinear Effects in Multimode Optical Fibers for Multiphoton Endomicroscopy.

Area of Science:

• Biomedical Optics
• Optical Diagnostics
• Gastrointestinal Imaging

Background:

• Multiphoton endomicroscopy (MPEM) provides high-resolution, in vivo imaging of gastrointestinal (GI) tissue, crucial for detecting precancerous conditions and early GI cancer.
• MPEM leverages endogenous fluorophores and nonlinear optical effects for label-free imaging, offering an alternative to traditional biopsy and histology.
• Current limitations in MPEM implementation stem from challenges in delivering ultrashort laser pulses and achieving desired wavelengths for excitation.

Purpose of the Study:

• To review the biophysical principles of MPEM for GI tissue.
• To analyze existing endoscopic architectures for multiphoton excitation (MPE).
• To explore the potential of nonlinear effects in multimode optical fibers for advancing MPEM.

Main Methods:

• Review of multiphoton microscopy biophysics in GI tissue.
• Analysis of current multiphoton endomicroscopy architectures.
• Investigation of nonlinear optical phenomena in multimode optical fibers, including beam self-cleaning (BSC) and supercontinuum generation.

Main Results:

• MPEM enables visualization at epithelial, extracellular matrix, and subcellular levels, assessing metabolic status and stromal remodeling.
• Multimode optical fibers offer solutions for delivering ultrashort pulses and broadening optical spectra for MPE.
• Beam self-cleaning (BSC) and supercontinuum generation in optical fibers are identified as key enabling nonlinear effects.

Conclusions:

• MPEM is a promising technology for early GI cancer detection, offering label-free, in vivo histological assessment.
• Overcoming technical challenges in laser pulse delivery is critical for widespread MPEM adoption.
• Integrating multimode optical fibers with nonlinear effects like BSC can significantly advance MPEM, leading to a new generation of high-resolution diagnostic instruments for GI malignancies.