Broad band antireflection coating on silicon from 1.5 to 6 μm spectral band

摘要: Abstract Silicon is one of the easily available, low cost and stable material transmitting in 1.5–6 μm spectral band. Silicon’s optical application includes thermal imaging, motion sensors forward looking infrared (FLIR) technology. In this work a broad band antireflection coating on silicon substrate for reported. design, gradient index approach used which very useful tool to achieve coating. To realize profile, refractive assumed increase from 1.45 (thorium fluoride chosen as material) 3.42 five discrete optimized steps. The design was conceived with thorium first layer next air each other four layers were replaced by two equivalent combination fluoride. This nine deposited e-beam evaporation system has total thickness only 879 nm. Experimental results shows average transmission 96% region 5 mm thick substrate. also 96.3% 1.54 μm eye safe laser 96.5% 3–5 μm wave bands. environmentally stable, tested per MIL standard.