Ho3+-doped CALGO crystals for high-power ultrafast 2.1-{\mu}m lasers

TL;DR

This paper reviews recent advances in Ho3+-doped CALGO crystals used as gain media for high-power ultrafast 2.1-μm lasers, highlighting their unique properties, demonstrated systems, and future potential.

Contribution

It provides a comprehensive summary of recent experimental achievements, spectroscopic characterization, and future outlook for Ho:CALGO lasers in ultrafast laser technology.

Findings

Demonstrated high-gain and broad spectra in Ho:CALGO crystals.

Achieved ultrashort pulse generation and amplification at high power.

Outlined future directions for performance scaling of Ho:CALGO lasers.

Abstract

Ho3+-doped disordered CaAlGdO4 (CALGO) crystals have recently emerged as a promising gain material platform for next-generation high-power ultrafast 2.1-{\mu}m laser systems. This laser gain material offers a unique combination of high-gain, small quantum defect, inhomogeneously broadened spectra, and good thermal conductivity, enabling ultrashort pulse generation and amplification at high-average power and high pulse energy. Many systems, including mode-locked oscillators and amplifiers with state-of-the-art performance, have been demonstrated in the last few years that promise to meet growing application demands for efficient ultrafast laser technology in this wavelength region. In this review paper, we summarize recent achievements using this gain material both in oscillators and amplifiers and place these results in the state-of-the-art of 2-{\mu}m ultrafast laser technology, present detailed spectroscopic characterization of this material, and discuss future perspectives of further performance scaling of Ho:CALGO lasers.