PASSIVE Q-SWITCHES Fe²+:ZnSe and Fe²+:ZnS PASSIVE Q-SWITCHES Fe²+:ZnSe and Fe²+:ZnS saturable absorbers (SA) are ideal materials for passive Q-switches of solid-state lasers operating in the spectral range of 2.5-4.0 μm. These lasers (e.g. 3.0 μm Er:YAG/YSGG/YLF) are used for pumping middle-infrared Optical Parametric Oscillators and for numerous medical and dental applications. SINGLE_A IPG’s fabrication process allows low cost mass production of a very large variety of diffusion-doped Fe²+:ZnSe/Zns crystals with low losses, uniform distribution of iron, good reproducibility and reliability. Samples of Fe²+:ZnSe Single and Polycrystalline Saturable Absorbers Absorption Spectra of Fe²+:ZnS & Fe²+:ZnSe Saturable Absorbers Experimental Results for Transmission vs. Fluence in Fe:ZnSe (circles) Numerical fit for σgsa = 0.6x10-18 cm² at 2.8

Fe²+:ZnS and Fe²+:ZnS Passive Q-Switches gsa /esa According to the criterion for Saturable Absorber Q-switching: Fe:ZnSe/S can be used as a saturable absorber Q-switch for the Cr:Er:YSGG laser without intracavity focusing. Output energies of 15 and 85 mJ were achieved in single and multipulse modes of operation, respectively. The combination of • high values of saturation cross-section, • small saturation energy with good opto-mechanical (damage threshold – 2 J/cm2) and • physical characteristics of ZnSe and ZnS hosts makes Fe2+:ZnSe/S crystals an ideal market for passive Q-switching of mid-infrared...