Highly versatile confocal microscopy system based on a tunable femtosecond Er:fiber source.

Area of Science:

• Optics and Photonics
• Biomedical Imaging
• Laser Physics

Background:

• Confocal microscopy requires optimized light sources for high-resolution imaging.
• Linear and nonlinear imaging techniques offer complementary information but demand versatile laser systems.

Purpose of the Study:

• To evaluate a single femtosecond fiber laser system for both linear and nonlinear microscopy.
• To explore the system's performance across a wide range of pump wavelengths.
• To demonstrate its capabilities for advanced imaging applications.

Main Methods:

• Utilized a tunable femtosecond fiber laser system.
• Employed linear fluorescence excitation and nonlinear imaging techniques (two-photon and three-photon absorption).
• Optimized pulse duration using a prism compressor for dispersion control.

Main Results:

• Demonstrated benefits of a tunable visible spectrum laser for fluorescence excitation.
• Achieved sub-33 fs pulse durations in the confocal region.
• Enabled two-photon microscopy of mouse brain tissue with 2 mW average power at 1100 nm.
• Induced localized photodamage in DNA using three-photon absorption.

Conclusions:

• The compact femtosecond fiber laser system is highly versatile for diverse microscopy applications.
• The system shows significant potential for deep-tissue imaging in the near-infrared window.
• Higher-order nonlinearities can be effectively exploited for precise biological sample manipulation.