MHz-Rate Cr:ZnS Amplifier Providing 2.7 W of Pulses with Sub-10-fs Transform Limit at 2.3 μm

Solid-state laser oscillators based on Cr<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> -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 xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">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 xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> plate to a transform limit of sub-10 fs.