Development prospects and stability limits of the mid-IR Kerr-lens   mode-locked lasers
  The Kerr-lens mode locking ability and the ultrashort pulse characteristics are analyzed numerically for the Cr-doped ZnTe, ZnSe, ZnS active media. The advantages of these materials for the femtosecond lasing within 2 - 3 $\mu$m spectral range are demonstrated. 
V.L. Kalashnikov, E. Sorokin, and I.T. Sorokina