梯度膜作为高功率激光反射膜的初步研究

 对渐变折射率薄膜替代均匀膜系作为高功率激光反射膜的可行性进行了理论研究。以较容易获得的线性共蒸法制备的光学膜在中心波长为1 064 nm的激光作用为例，分析了薄膜与基体之间波长的匹配、场强分布等问题。提出了通过改变微小单元获得梯度膜匹配厚度的数值方法，将之运用在14个周期结构的梯度膜中，并由膜系计算软件验证了所获得结果。最后通过分析Maxwell方程，计算了梯度膜中与薄膜损伤密切相关的电场强度分布。结果表明：周期性结构梯度高反射膜中的电场分布与传统高反射膜具有相似性，但相对于传统高反射膜容易在界面处出现损伤的情形而言，梯度膜更容易在表面出现损伤，使梯度膜表面反射相移接近π是高功率梯度高反射膜的设计方向。

Gradient optical film taking the place of classical high-reflectivity film

The feasibility of gradient optical films taking the place of classical layered structure high-reflectivity films in the field of high power laser is theoretically studied. To study the wavelength matching and electric field distribution, an example that the laser of 1 064 nm wavelength transmits in gradient optical films which is prepared with linear co-evaporation method is given. A numerical method which is applied to the gradient film with 14 perioded structure is proposed to obtain the matching thickness. Based on the Maxwell equation, the distribution of electric field is calculated. The result indicates that the distribution is similar to the classical layered high-reflectivity film but gradient film is likely to get damaged in surface. The design object of gradient film is to make