Efficient High-Power Ultrashort Pulse Compression in Self-Defocusing Bulk Media.

Area of Science:

• Optics and Photonics
• Laser Physics
• Nonlinear Optics

Background:

• Femtosecond laser technology is advancing, with current near-infrared sources offering high average power.
• Shorter pulses (<100 fs) are crucial for applications like extreme ultraviolet and mid-infrared frequency conversion.
• Existing power-scalable pulse compression schemes are limited, necessitating further development.

Purpose of the Study:

• To develop and demonstrate a power-scalable pulse compression scheme for femtosecond lasers.
• To achieve significant pulse duration reduction while maintaining high average power.
• To investigate spectral broadening mechanisms in bulk materials for efficient pulse compression.

Main Methods:

• Experimental compression of 90 W average power, 190 fs pulses to 70 W, 30 fs.
• Utilized cascaded phase-mismatched quadratic nonlinearities in Beta Barium Borate (BBO) crystals.
• Performed simulations comparing spectral broadening in self-focusing and self-defocusing media, analyzing spatially resolved spectra.

Main Results:

• Successfully compressed 190 fs pulses to 30 fs at an average power of 70 W.
• Increased peak power from 18 MW to 60 MW.
• Demonstrated that balancing self-defocusing and Gaussian beam convergence enables efficient spectral broadening in bulk material.

Conclusions:

• The presented cascaded nonlinear process in BBO crystals is an efficient and power-scalable method for femtosecond pulse compression.
• The findings pave the way for generating high-energy, ultrashort pulses beneficial for various scientific applications.
• Optimized spectral broadening in bulk media offers a viable route for advancing femtosecond laser capabilities.