Abstract

Pulse compression based on stimulated Brillouin scattering (SBS) in counterpropagating ns pump pulses [1] makes it possible to achieve a pulse width of ~110 ps in liquids such as perfluorooctane C₈F₁₈ [2] and carbon tetrachloride CCl₄ [3], as well as ~180 ps in fused quartz [4]. The most studied CCl₄ is toxic for use in medical lasers, is not suitable for phase conjugation in two-pass amplifiers as it is prone to optical breakdown and has a low reflectivity ~40% of the SBS-mirror. In contrast, the safety of C₈F₁₈ has been proven by its use as a coolant, tamponade in eye surgery and even as a breathable fluid. The high breakdown threshold and reflectance above 90% allow it to be used in high-energy >200 mJ two-pass phase-conjugated amplifiers [2]. Self-seeding of the SBS-compressor with CCl₄ allows to improve energy stability, reduce jitter, and achieve shorter pulses [3], albeit with an energy limited to ~1 mJ. The goal of this study was to compare different designs of self-seeded SBS-compressors with C₈F₁₈ to ensure ~90 ps high-energy pulses with a smooth beam suitable for laser dermatology.

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