Sub-50-femtosecond gain-managed amplified pulses enhance nonlinear ablation efficiency

Area of Science:

• Biomedical Engineering
• Laser Physics
• Materials Science

Background:

• Nonlinear femtosecond (fs) laser ablation allows precise energy deposition for cell microsurgery.
• Conventional systems face limitations at low (kHz) or high (MHz) repetition rates.
• Intermediate repetition rates with amplified pulse energy offer a balance of speed and thermal control.

Purpose of the Study:

• To develop a cost-effective, intermediate-repetition-rate femtosecond fiber laser system.
• To investigate the impact of sub-50-fs pulse durations on ablation efficiency and thermal effects.
• To demonstrate the system's capability for targeted subsurface microsurgery.

Main Methods:

• Custom-built a 32 MHz femtosecond fiber laser with gain-managed nonlinear amplification.
• Achieved pulse energy boost from 5 to 90 nJ and pulse duration compression to 46 fs.
• Evaluated ablation efficiency in silicon and cell membrane damage using varying pulse durations.

Main Results:

• Shorter (sub-50-fs) pulses doubled ablation efficiency in silicon and increased cell membrane damage by approximately 10× compared to longer pulses.
• The system enabled targeted subsurface ablation up to 400 µm deep in 3D tumor models using 6 nJ pulse energy.
• Multi-pulse incubation effects were leveraged for cumulative energy deposition at reduced per-pulse energies.

Conclusions:

• Intermediate-repetition-rate femtosecond lasers with short pulse durations enhance ablation efficiency and precision.
• This technology facilitates advanced microsurgical applications, including deep subsurface ablation.
• The findings guide the development of next-generation femtosecond laser systems for microsurgery.