Research On Optical Thin-film Reflective Color Filters

With the development of imaging and display technology, the reflective color filters used in image sensing, color display, decoration and laser are mentioned more and more. But the reflective color filters now are complex, hardly fabricated and costly. Therefore they are confronted with the bottleneck. This paper introduces a reflective color filter with metal-dielectric thin films structure. The method to achieve a color filter with a high reflection and a wide rejection area within visible range is analyzed by the theory of optical thin films. The characters of this filter are optimized via improving designs and inverting parameters. A multi-peak reflective filter that works via matching the phase of a reflective dielectric thin film stack in it is introduced. The design and process to fabricate an array of these metal-dielectric thin films color filters is discussed too. Red, green and blue basic color filters and the array composed with them are fabricated. Two peaks and three peaks reflective filters working in visible range are fabricated and tested too. The main contents are arranged as follows:1. Design and fabrication of reflective optical thin-films color filters. A simple and easy realized metal-dielectric thin-films structure is designed through the method of induced reflection. The influence to the filter's optic characters of very thin film is analyzed and parameters of an ultra-thin metal film are inverted. Red, green and blue reflective filters with the reflectance larger than 72%, wide reflective area and large color gamut were obtained.2. Design and fabrication of reflective optical thin film color filters array. The process composed with optical coating, lithography and lift-off technologies to realize an array of color filters is investigated. Lithography masks and color pixels are designed. In experiments, reflective color filter array is fabricated, which could statically display color images and characters, and also could realize intermediate colors among red, green and blue.3. Design and fabrication of multi-peak reflective optical thin-films color filters. The blue and red double peaks reflective filter based on induced reflection method is designed and fabricated. Red, green and blue three peaks reflection filter is designed and fabricated via the structure composed with an ultra-thin metal film and a dielectric thin film stack. Three peaks light flitting is realized by a phase match method based on the Fabry-Perot structure without a spacer film.