| Laser trimming as a post-processing technology to enhance device performance and improve the yield, has been widely used in semiconductor industry. Over the past several decades, there was a growing concern in the use of photosensitive materials for a wide range of applications in the fields of optics including diffractive optical elements, optical recording, and antireflective coatings. A thought about laser trimming of thin film filters was put forward. The use of photosensitive materials for manufacturing various functional optical filters would be a very attractive way for enabling the post trimming of such devices with the help of a light beam. It could not only correct some material deposition errors accurately to improve the production efficiency, but also create entirely new filtering devices with controlled spatial properties such as apodizing filter and linear variable filter.A new organic-inorganic hybrid material, that shows photo-induced reduction of refractive index as well as volume contraction, has been prepared using a sol-gel method. This material was then coated on a Si substrate by spin-coating to manufacture film. After irradiated by ultraviolet light with a deuterium lamp for five hours, the thickness of film decreased largely by 55%, and the refractive index of film changed from 1.484 to 1.445@550nm. Significantly, the film's optical thickness exhibits a exponential change with the irradiation time increasing. It provides us with the meaningful possibility of controlling this film's optical thickness accurately by adjusting exposure time. Futhermore, photo-patternning of the organic-inorganic hybrid film without any further process (wet etching, thermal curing) is performed utilizing the volume contraction on UV-light irradiation. Thus, this film has potential applications to fabricate patterned filter array and apodizing filter by direct light writing. The film also shows good temperature stability and immunity to visible light exposure.
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