Resolution improvement in two-photon fluorescence microscopy with a single-mode fiber

Area of Science:

• Optics and Photonics
• Biomedical Imaging

Background:

• Ultrashort pulsed lasers are vital for advanced microscopy techniques like two-photon fluorescence microscopy.
• Nonlinear optical effects in optical fibers can alter laser pulse characteristics, impacting imaging performance.

Purpose of the Study:

• To experimentally investigate the spectral broadening of ultrashort pulsed laser beams in optical fibers.
• To determine the impact of fiber length and illumination power on spectral characteristics for two-photon fluorescence microscopy applications.

Main Methods:

• Experimental characterization of spectral broadening in a single-mode fiber.
• Varying fiber length and illumination power to observe changes in spectral width and blue shift.
• Measurement of axial response using a two-photon fluorescence polymer block.

Main Results:

• Spectral width and spectral blue shift increase with both fiber length and illumination power.
• A 3-m single-mode fiber with 400 mW illumination power resulted in a 15 nm spectral blue shift.
• The spectral blue shift improved resolution in two-photon excitation but slightly reduced excitation efficiency due to temporal broadening.

Conclusions:

• Nonlinear fiber optics significantly influence ultrashort pulsed laser characteristics.
• Optimizing fiber parameters is essential for balancing resolution enhancement and excitation efficiency in two-photon microscopy.
• Spectral blue shift offers a pathway to improved resolution in two-photon fluorescence microscopy.