Preparation and optical properties of diamond thin films based on fused silica substrates

Diamond and diamond film have excellent performance in optics, electricity, mechanics, chemical stability, etc. Compared with bulk materials, diamond film has low cost and short preparation period, and has good laser damage characteristics, which can replace traditional films to achieve high performance. The laserinduced damage threshold, optical properties and morphology of diamond films are closely related to the growth conditions. In this paper, high-quality diamond films suitable for laser applications were grown on the surface of fused silica by microwave plasma chemical vapor deposition, and the effects of gas flow ratio and temperature on the optical properties of diamond films were studied. The effect of particle morphology on electric field and temperature field. Studies have shown that the growth quality of nanocrystalline diamond films is closely related to the flow ratio of methane/hydrogen and the growth temperature. When the flow ratio of methane/hydrogen is 3%, and the growth temperature is around 800℃, the surface roughness of the film is the lowest. The diamond film shows a morphology of (111) facets, the grain size is in the 20~200nm range, and the transmittance can reach up to 70%. The simulation of the laser electric field and temperature rise with different surface grain shapes shows that the grains of (111) facet can cause the electric field to increase by 2~4 times, and the temperature rise reaches 40~60℃.