Two-photon fluorescence imaging with 30 fs laser system tunable around 1 micron

Area of Science:

• Optics and Photonics
• Biomedical Imaging
• Laser Physics

Background:

• Ultrafast laser systems are crucial for nonlinear optical microscopy.
• Developing cost-effective, high-performance lasers remains a key challenge.
• Existing systems may lack tunability or sufficient power for advanced applications.

Purpose of the Study:

• To develop a low-cost, tunable, high-peak-power ultrafast laser system.
• To introduce a figure of merit (FOM) for optimizing laser design for nonlinear imaging.
• To demonstrate the system's capability for multimodal nonlinear imaging.

Main Methods:

• Utilized a SESAM-modelocked Yb tungstate laser.
• Incorporated spectral broadening via microstructured fiber.
• Employed a prism compressor for spectral selection, tuning, and pulse compression.

Main Results:

• Achieved tunable output from 800 to 1250 nm.
• Obtained pulse durations down to 25 fs with average power up to 150 mW at 80 MHz.
• Demonstrated high signal-to-noise ratio two-photon fluorescence images of biological samples.

Conclusions:

• The developed laser system is suitable for multimodal nonlinear imaging (TPE, SHG).
• The introduced FOM serves as a guideline for laser design in microscopy.
• The system shows potential for applications like THG, CARS, and nanosurgery.