Effect of metal grids configuration on photothermal properties of infrared optical windows

Abstract

Plating metal grids on the surface of infrared optical materials can effectively enhance its electromagnetic shielding performance. In this research, fused silica optics were plated with different configurations design (with a duty cycle of 5.5%) of Au-based metal grids, and the light-field distribution and light transmittance of fused silica were simulated as well as the temperature testing was carried out. The results show that the metal grids configuration has marginal effect on the light field intensity, since the Au-based grids with the duty cycle of 5.5% make Light Intensification Factor (LIF) remain constant at 2.95 regardless of its linewidth and period. But the occurrence probability of maximum electric/light field is increased when increasing the linewidth of metal grid, indicating that wider grid has no benefit the light modulation substrates. The metal grids in 6 μm linewidth deteriorates the infrared window transmittance by 3.48%. When exposure upon continuous infrared laser, the temperature of sample increases with illumination time. And the most significant temperature rise was observed for the metal grid configuration with a linewidth of 10 μm and a period of 359 μm, reaching as high as 390.75 K when irradiated for 60 s.