Radial IR-GRIN lens prepared by multi-temperature fields manipulated gradient crystallization within chalcogenide...

Chalcogenide glass has achieved great success in manufacturing axial-type infrared gradient refractive index (IR-GRIN) lenses. However, studies on radial-type IR-GRIN lenses, which are more ideal for optical design, remain rare. The present study introduces what we believe to be a new method for preparing radial IR-GRIN lens by creating high refractive index (n) In₂S₃ nanocrystals within a 65GeS₂-25In₂S₃-10CsCl (GIC, in molar percentage) glass matrix. Upon introduction of multi-temperature field manipulation, we have successfully achieved central crystallization and simultaneous gradient attenuation spreading toward the edge within GIC glass, providing a radial GRIN profile with Δn over 0.1 while maintaining excellent IR transparency. In addition, the optical and structural properties of the GIC GRIN samples were characterized. The relationship between Raman intensity and the n of glass ceramics at different heat treatment temperatures was investigated, thereby enabling the indirect confirmation of the presence of radial gradient crystallization within the prepared GIC GRIN samples through Raman intensity. Multiple experimental results have shown that this approach has excellent reproducibility and potential for large-scale productions.