High repetition rate green-pumped supercontinuum generation in calcium fluoride

Area of Science:

• Nonlinear Optics
• Laser Physics
• Materials Science

Background:

• Supercontinuum generation is crucial for various spectroscopic applications.
• Optimizing nonlinear crystal usage is key for efficient and durable laser systems.
• Understanding optical damage mechanisms is vital for material longevity.

Purpose of the Study:

• To compare supercontinuum generation using tight versus loose focusing in nonlinear crystals.
• To evaluate the impact of focusing geometry on spectral extent and material durability.
• To investigate optical degradation mechanisms and their effect on supercontinuum output.

Main Methods:

• Utilized 150 fs, 515 nm pulses from an amplified Yb:KGW laser.
• Compared tight and loose focusing configurations into different lengths of nonlinear crystals.
• Monitored supercontinuum spectral properties and material damage over time.
• Performed numerical simulations of filament propagation.

Main Results:

• Loose focusing into a long crystal (25 mm) yielded broader supercontinuum spectra.
• Loose focusing demonstrated significantly longer damage-free operation (20 min) compared to tight focusing (2 min).
• Optical degradation, indicated by luminescence and scattering, correlated with damage onset.

Conclusions:

• Loose focusing into long nonlinear crystals is advantageous for supercontinuum generation.
• This geometry enhances spectral breadth and material operational lifetime.
• Findings provide insights into optimizing laser-crystal interactions for robust supercontinuum sources.