Research On Tunable Wavelengths And Bandwidths Of Optical Devices Coating

In this paper, we prepared various of cut-off interference filters in order to adjust the wavelength and bandwidths of modern optical devices, and especially, the short wavelength pass filters were investigated in detail which were difficult to design and prepare. Based on the principle, TiO₂ was chosen as the material of high refractive index and SiO₂ as the material of low refractive index. Periodicity of short wavelength pass filter was theoretically designed according to the concept of equivalent refractive index. The main film system and the spectrum curve of the short wavelength pass filter are presented. The design of the film system need revised.since its transmittance did not meet the requirement at some range wavelength. We correct film system using MCalc-Yu software. As a result of the correction, the best way to make the film system was found. During the process, the key is to control the thickness of coating. The process of manufacture adopted the method of measuring quartz' frequency to control the film's thickness. The measuring result turned out that both ideal curve and practical curve is very similar and get the requirement of technology. Finally, the adjustion of wavelength and bandwidths could be carried out by matching the various of short wavelength pass filters with the various of long wavelength pass filters.