Investigation Of Multi-channel Filter Based On Photo-sensitive Material

Existing fabrication process of multi-channel optical thin film filter has drawbacks of complexity and low yield rate. However, when photo-sensitive materials which have gained great success in integrated optics components come into the field of traditional thin film optics, post-deposited thin film filters can be modified and patterned.In this paper, we combined the optical thin film technology and photo-sensitive material to investigate a new method of fabricating multi-channel filters that avert the complexity of traditional process. We have achieved accomplishment in several points:1) Based on the hydrolysis of polymer siloxane MTPS, doping with photo-initiator agent BDK, organic and inorganic hybrid materials synthesized with sol-gel method. A significant increase in the refractive index and physical thickness of this material after 60 min UV exposure is observed as well as optical thickness change of 60% in the doping of 50% under the conditions of exposure. This material is easy to deposit film with uniform surface and is insensitive to visible light. The film is anti-photoaging and in the visible spectrum the loss is small, so it can be used as spacing layer interference filters. Photosensitive mechanism analysis showed that the photo-sensitivity of the material derived from the modification of the agent groups on the inorganic structure and polymerization.2) The film preparation method for the material is explored, including substrate treatment, the rotation speed and time of spin coating, film post-processing, high temperature heat treatment temperature and annealing process factors. Single layer film of photosensitive material is prepared and the changes in characteristic parameters of the optical and UV exposure parameters are determined.60 min time of exposure and measurement showed that UV exposure increased the film refractive index from 1.558 to 1.592, the physical thickness from 288 nm to 422nm.3) Mask of 10μm to 100μm scale pattern is designed and produced, with which the reproduction of the mask pattern on the film is well performed. The transmissive optical filters of the Fabry-Perot structure is designed and produced, with seven channels exposed for various time to prepare the multi-channel filter with centre wavelength at 550 nm. We use photosensitive material film with thickness of 300 nm to prepare the reflection type optical filters, with the blue and green colour graphics.