Micro-Optic Mach-Zehnder Interferometric Sensor for UV Detection Using Photochromic Dye

A micro-optic Mach-Zehnder interferometric UV sensor that consists of a polymer film containing a photochromic dye is presented. Spirooxazine, which is a UV-sensitive material having high sensitivity and fast response and recovery was used as the photochromic dye. Sensor characteristics were analyzed with polymer films containing 0.5, 1.0, and 1.5 wt% of spirooxazine. When the sensor was irradiated with UV light of intensity ranging from 0 to 80 mW/cm(2) for 5 s, the wavelength of the highest extinction ratio was found to shift by 0.033, 0.039, and 0.0435 nm/mW for spirooxazine concentrations of 0.5, 1.0, and 1.5 wt%, respectively. Also, the recovery time was less than 30 s. The wavelength shift of the highest extinction ratio shows that the proposed sensor has a linear response. Although the sensitivity of the proposed micro-optic Mach-Zehnder interferometric UV sensor is low, it has a linear response to even high intensity UV radiation and does not become saturated.