中国激光, 2006, 33 (7): 959, 网络出版: 2006-08-08
强吸收衬底上薄膜厚度和折射率的测量新方法
New Measurement Method of Thickness and Refractive Index of the Film Grown on the Strong Absorption Substrate
薄膜 膜厚 折射率 类波导结构 强吸收衬底 自由空间耦合 thin films thickness refractivity analogue waveguide configuration strong absorption substrate free-space couple
摘要
提出了一种同时测量强吸收衬底上薄膜厚度和折射率的方法。对生长于强吸收衬底上的透明薄膜,提出在该薄膜上镀一层薄金属,形成金属-薄膜-强吸收衬底的类波导结构。由于小角度入射光在强吸收衬底上具有较强的反射率,使该结构可容纳一系列共振模。利用自由空间耦合技术和导出的共振模模式本征方程,同时确定透明薄膜的厚度和折射率。实验中测量了硅衬底上制备的聚甲基丙烯酸甲酯(PMMA)薄膜的折射率和厚度,测量的相对误差均小于10-3。该方法具有简便、可靠、可测量任意折射率薄膜的优点。
Abstract
A measuremant method of thickness and refractive index of film grown on the strong absorption substrate is proposed. A thin metal layer is deposited on a transparent film which is grown on a strong absorption substrate. As a result, an analogue waveguide configuration of metal-transparent film-absorption substrate, which can accommodate a series of resonant modes, is formed due to a bigger reflectivity on the absorption substrate for the small angle of incidence. Based on the free-space coupling technique and the eigenvalue equation of the resonant modes derived by the standard electromagnetic field theory, the thickness and refractive index of the transparent film are simultaneously determined with a relative error of 1×10-3. The proposed method is simple and reliable, and can be used for the film with different refractive indexes.
张竞, 曹庄琪, 陆海峰, 李红根, 沈启舜. 强吸收衬底上薄膜厚度和折射率的测量新方法[J]. 中国激光, 2006, 33(7): 959. 张竞, 曹庄琪, 陆海峰, 李红根, 沈启舜. New Measurement Method of Thickness and Refractive Index of the Film Grown on the Strong Absorption Substrate[J]. Chinese Journal of Lasers, 2006, 33(7): 959.