Passive Q-Switches

Fe2+:ZnSe, Fe2+:ZnS

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.

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.

Fe2+:ZnSe Single and Polycrystalline Saturable Absorbers

Samples of Fe2+:ZnSe Single and Polycrystalline Saturable Absorbers

 Passive Q-Switch Fe2+:ZnSe Datasheet


Crystal  Peak Coefficient Absorption, cm-1 Upper Level Lifetime
at 300 K, µs
 σGSA at
2.8 µm, 10-20 cm2
σgsa/σesa σgsa/σYSGG
Fe:ZnSe  1-20 0.37 90 0 30
Fe:ZnS 1-20 <0.3 130 0 43


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 a high values of saturation cross-sectio, small saturation energy with good opto-mechanical (damage threshold - 2 J/cm2) and physical characteristics of ZnSe and ZnS hosts make Fe2+:ZnSe/S crystals an ideal material for passive Q-Switching of mid-infrared laser cavities.

Contact IPG Photonics for more information