Research on ultra-smooth surface processing of mid-infrared indium fluoride-based fiber glass

The advancement of mid-infrared (MIR) laser technology and devices is closely linked to the development of suitable MIR materials. Fluoride glasses are among the leading candidates for MIR fiber applications, with indium fluoride-based glass emerging as a promising research focus for achieving high-performance optical materials. This study presents a novel approach by designing a polishing experiment on indium fluoride glass to explore the mechanisms for achieving superior optical surface quality. Combining traditional chemical-mechanical polishing (CMP) experiments with multi-field finite element simulations , the study investigates surface planarization and the underlying processes influencing optical quality . The results show that indium fluoride glass exhibits no crystallization behavior during processing and achieves a surface roughness (Rq) of 3 nm under alkaline conditions at pH 11, with a material removal rate of 19.39 µm/min. The polished glass demonstrates a transmittance exceeding 90 % within the 2.5–8 µm MIR range, with no detectable damage or defects. This work provides new insights into the surface processing of indium fluoride glass, offering valuable guidance for its application in MIR fiber optics . • A novel surface processing method for fluorine-indium glass was developed, revealing its planarization mechanism. • Using a pH11 polishing solution achieves high optical quality without crystallization or defects. • Experiments and multiphysics simulations show a surface roughness (Rq) of ∼3 nm, >90 % mid-IR transmittance, and ∼19 μm/min removal rate.