Long-wave IR femtosecond supercontinuum generation with Cr:ZnS lasers

We give an overview of experimental results on mid-IR femtosecond lasers and frequency combs based on polycrystalline Cr$^{2+}$: ZnS providing access to few-cycle pulses in the spectral range 2–$;3\mu \mathrm{m}$. We also discuss the techniques for generation of multi-octave coherent femtosecond continua with Cr$^{2+}$: ZnS lasers.