Ultralow voltage imprinting in GeS2–Ga2S3–AgI glasses for visible to middle-infrared diffraction gratings

Abstract

A diffractive optical element (DOE) covering visible to middle-infrared regions is imprinted in chalcohalide glass by microthermal poling under ultralow voltages (~125 V). The effect of the poling voltage on the surface profiling, optical diffraction, optical transmittance, and anode-side structural rearrangement is investigated. Deformation of the surface profiling and diffraction order increase with increasing poling voltage, showing a saturation voltage of 125 V and a decrease in the transmittance within 10%. In addition to the normal vertical migration of silver ions, an obvious and unexpected transverse migration of silver ions and mutual structural transformation occur between homopolar bonds Ge–Ge (Ga–Ga) and S–S and the heteropolar bond Ge–S (Ga–S), which are key to forming the surface profiling and subsurface structures. Formation of the DOE mainly depends on the periodic subsurface microstructure rather than surface profiling. Thus, simple and inexpensive processes can fabricate broadband wavelength-based DOEs for military, medical and biological applications.