激光入射角度对薄膜热场分布影响的数值分析

在多层介质薄膜中，激光的入射方式是影响薄膜抗损伤能力的关键因素之一.提出了一种模拟锥角高斯光入射多层介质薄膜后电场和热场分布的方法.该方法能够分析薄膜中高斯光各个角谱分量叠加形成的电场分布，进而得到由于薄膜本征吸收产生的热量沉积以及薄膜内部的温度场分布.针对中心波长为4.3 μm的中红外高反膜进行了分析，给出了高反膜系的温升峰值随激光入射角度和偏振态的变化.结果表明：对于s偏振光，斜入射时膜系的最高温升峰值高于垂直入射峰值，而p光的结果则相反.此种模拟方法克服了原有方法对激光入射角度的限制，较好地反映出斜入射情况下激光偏振态对薄膜损伤的影响. 关键词： 多层介质薄膜 高斯光 热过程 数值分析

Numerical analysis of thermal response of mid-infrared high reflectance coating under different laser irradiation angles

Thermal response of mid-infrared high reflectance coating exposed to laser beam of wavelength of 4.3 μm at different incident angles was studied by numerical method. In this paper, the incident beam was modeled as a tapered wave with a Gaussian spectrum. Joule loss due to absorption in the absorptive layers was calculated analytically and temperature profile in the multilayer was presented. The temperature distributions of high reflectance coating with different incident angles of transverse electric (TE) mode and transverse magnetic (TM) mode laser beams were compared. For the TE mode laser, the highest temperature peak appears at the incident angle of 35°, for the TM mode, the magnitude of the temperature peak decreases with increasing incident angle.