Bulk Supercontinuum Generation for Ultra-CEP-Stable Single-Cycle Pulses at $\upmu\mathrm{m}$

Single-cycle laser pulses with a precisely controllable carrier-envelope phase (CEP) form the basis for studying fundamental light-matter interactions on the genuine attosecond time scale of the light's electric-field evolution. In the past, this paved the way for ground-breaking experiments, such as the generation of isolated attosecond pulses [1], or the sub-femtosecond manipulation of electric currents in solids [2]. Until recently, kHz-rate Ti:sapphire (Ti:Sa) amplified laser systems, running at wavelengths around 800 nm, have been the workhorse for generating CEP-stable pulses with single-cycle durations [2]. Increasing demand arises for CEP-stable, MHz-rate single-cycle sources at longer wavelengths, allowing to excite a broad range of low-bandgap materials. Laser oscillators based on Cr
²⁺
-doped II-VI gain media have evolved as alternatives to Ti:Sa technology with emission wavelengths around 2–3 μm [3], which can be efficiently post-compressed in bulk material [4].