Thin film optical waveguide type UV sensor using a photochromic molecular device, spirooxazine

New waveguide type UV sensor using photochromic dye as a molecular light transducer has been studied. When exposed to UV radiation, thin film UV sensing membrane that is composed of spirooxazine derivative and polymer matrix (PMMA, poly(methyl methacrylate)) shows remarkable light absorption in the visible range (λmax=587 nm) reversibly from the original characteristics of spirooxazine dye. Since this polymeric thin film can also act as an intrinsic waveguide, it is useful to construct planar waveguide type sensor. The output intensity of inputted and guided visible light (λ=633 nm, He–Ne laser) through planar thin film waveguide was decreased according to the amount of photochromic dye absorbance by the UV photon energy in the optical path. The sensitivity of waveguide type UV sensor was 64 times greater than that of a traditional transmittance type polymer membrane.