利用泄漏波导测量低折射率薄膜的折射率和厚度

根据泄漏波导原理对K_9玻璃基板上的冰晶石薄膜进行折射率测量,达到的精度为1×10~(-4),与真实波导的情况相似。文中讨论了利用添加高折射率薄层减小待测薄膜的最小厚度的可能性。文中还利用光电方法观察反射光中暗条纹的方法判别波导的激发,并测出了冰晶石薄膜在4500到6500范围内的折射率。

Determination of refractive index and thickness of a low index thin film by leaky waveguide technique

Based on the principle of leaky waveguide, we made measurement of the refractive index of a cryolite film deposited on a K9 glass substrate. The accuracy is about 1 x 10-4, which is similar to that for a real waveguide. Possibility of decreasing the minimal measurable thickness of the film by insertion of a high index thin layer between the substrate and the film to be measured is discussed. When a white light source is used, we make judgement of waveguide excitation by observing the dark m-lines in the reflective light; in this way,the refractive of the cryolite film in the wavelength range from 4500A to 6500 A is determined.