UV Sensor Based on Photomechanically Functional Polymer-Coated FBG

A simple ultraviolet (UV) sensor based on a photomechanical responsible material (azobenzene moiety) and a typical fiber Bragg grating (FBG) has been proposed and demonstrated for the first time. This sensing device, called the azobenzene-coated FBG sensor, can easily measure the UV light intensity by determination of its center wavelength shift which results from the photoisomerization of the azobenzene moieties. We show that the peak wavelength can be rapidly shifted up to 0.6 nm because of the photomechanical stretching effect of the azobenzene-coated FBG. The strain applied to the FBG under a UV intensity of 208 mW/cm² was estimated to be 0.054%. We have also confirmed the linearity and stability of our proposed UV sensor.