Scaling of broadband Ho:CALGO regenerative amplifier to multi-mJ pulse energy

TL;DR

This paper demonstrates the energy scaling of a 2.08-μm Ho:CALGO regenerative amplifier to multi-mJ pulse energies at kHz rates, highlighting improvements in seed laser design and stability across different repetition rates.

Contribution

The study introduces an upgraded seed laser and explores bifurcation-free energy extraction, enabling higher pulse energies and stable operation at various repetition rates.

Findings

Achieved multi-mJ pulse energies at 30 kHz and above

Demonstrated stable 3.4-mJ pulses at 1 kHz

Discussed potential for further energy and duration scaling

Abstract

We report on energy scaling of a 2.08-{\mu}m wavelength regenerative amplifier (RA) system based on the broadband gain material Ho:CaAlGdO4 (CALGO) to multi-mJ pulse energy at kHz repetition rates. Compared to previous reports, energy scaling was enabled thanks to an upgraded seed laser with a higher fluence and better spectral overlap to the gain spectrum of Ho:CALGO, which increased amplification efficiency. Bifurcation-free energy extraction was investigated experimentally and numerically for various repetition rates. A stable output was obtained at 10 W average power for repetition rates of 30 kHz and above. In addition, stable 3.4-mJ energy extraction was achieved at a 1-kHz repetition rate. We discuss the further scaling potential of pulse energy and pulse duration.