Compact multicolor two-photon fluorescence microscopy enabled by tailorable continuum generation from self-phase...

Area of Science:

• Ultrafast optics
• Biomedical imaging
• Nonlinear fiber optics

Background:

• Multicolor two-photon microscopy requires broadband, tunable ultrashort pulses.
• Generating few-optical-cycle pulses with controlled spectral properties is challenging.
• Existing methods often lack efficiency or require complex pulse shaping.

Purpose of the Study:

• To demonstrate a novel method for generating plural few-optical-cycle pulses.
• To enable multicolor two-photon tissue imaging via wavelength mixing.
• To optimize a compact laser source for deep-tissue microscopy.

Main Methods:

• Utilized a 24-MHz Chromium:forsterite laser with anomalous dispersion.
• Managed fiber-optic nonlinearity to control soliton and dispersive wave generation.
• Achieved phase-matched spectral broadening to create a broadband continuum (830-1200 nm).

Main Results:

• Generated 5-nJ pulses with 10.5 fs duration and spectral enhancement at 920 nm.
• Demonstrated simultaneous three-color two-photon tissue imaging with contrast management.
• Achieved 500-µm imaging depth with low illumination power (14 mW).

Conclusions:

• Developed an efficient and compact laser source for multicolor two-photon fluorescence microscopy.
• The method allows for easy pulse compression without active pulse shaping.
• This approach is suitable for advanced ultrafast investigations and strong-field applications.