Femtosecond Cr2+:ZnSe Laser with Mode-Locking Based on Carbon Nanotubes

The ultrashort pulse laser based on a Cr²⁺:ZnSe monocrystal has been presented, utilizing carbon nanotubes as a saturable absorber. The saturable absorber consists of a sapphire substrate onto which nanotubes are deposited. Such a structure enables the realization of an element capable of simultaneously functioning as a saturable absorber and as a compensator for intracavity dispersion, as the substrate thickness can be chosen during fabrication, allowing for the adjustment of the introduced dispersion. Several laser resonator configurations are discussed, demonstrating the possibility of generating ultrashort laser pulses with durations down to 160 fs, a repetition rate of 135 MHz, an output power of 17 mW, and a central wavelength of 2.45 µm.