Holographic recording of volume phase Fresnel lenses in ZnSe semiconductor material.

Holographic recording of the relief-free volume phase Fresnel lenses in polycrystalline ZnSe semiconductor material, which is transparent from the visible to long-wave infrared wavelengths, is demonstrated. The room-temperature process of photomodification, which changes the refractive index of the semiconductor material dramatically (Δn=0.74-1.2) under illumination with low-intensity light, is used for recording the Fresnel lens employing a computer-generated photomask in the proximity configuration. The thin-plate volume phase diffractive optics offers broader functionality and at least three-fold cost reduction due to the saving of expensive material and labor. The possibility of recording of the volume phase diffraction gratings also in the active Cr-doped ZnSe material opens a door to the fabrication of mid-infrared lasers with narrowed and tunable emission spectra.