Overcoming Bifurcation Instability in High-Repetition-Rate Ho:YLF Regenerative Amplifiers

TL;DR

This paper presents a method to suppress bifurcation instability in high-repetition-rate Ho:YLF regenerative amplifiers, enabling high-energy pulses with low noise through gain saturation and temperature control.

Contribution

It introduces a technique to completely suppress bifurcation instability in Ho:YLF RAs by gain saturation and cooling, improving high-energy pulse extraction at high repetition rates.

Findings

Achieved 6.9 mJ pulse energy at 1 kHz with 1.1% fluctuations.

Suppression of bifurcation instability via gain saturation and cooling.

Observed temperature dependence of RA performance.

Abstract

We demonstrate a Ho:YLF regenerative amplifier (RA) overcoming bifurcation instability and consequently achieving high extraction energies of 6.9 mJ at a repetition rate of 1 kHz with pulse-to-pulse fluctuations of 1.1%. Measurements of the output pulse energy, corroborated by numerical simulations, identify an operation point that allows high-energy pulse extraction at a minimum noise level. Complete suppression of the onset of bifurcation was achieved by gain saturation after each pumping cycle in the Ho:YLF crystal via lowering the repetition rate and cooling the crystal. Even for moderate cooling, a significant temperature dependence of the Ho:YLF RA performance was observed.