MHz-rate Cr:ZnS amplifier providing 2.7 W of pulses with sub-10-fs transform limit at 2.3 µm

Abstract

Solid-state laser oscillators based on Cr²⁺-doped II-VI materials have emerged as reliable sources for generating broadband, few-cycle pulses in the 2-3 μm range [1]. Recent studies achieved nonlinear post-compression of the output of a Cr:ZnS oscillator to sub-8-fs, single-cycle duration via spectral broadening in a TiO<inf>2</inf> plate [2, 3], rendering Cr:ZnS oscillators promising drivers for multi-octave-spanning mid-infrared light generation [2]. However, the average power of such single-cycle pulses from an oscillator is limited to several hundred milliwatts, restricting possible nonlinear downstream applications. To address this, Cr:ZnS amplifiers are utilized [1, 4]. We developed an amplifier to boost the output power of a 25-MHz Cr:ZnS oscillator to 4.1 W with an M² of 1.1, and spectrally broadened the amplified pulses in a TiO<inf>2</inf> plate to a transform limit of sub-10 fs.