Chemical sensor for nitrate in water using long period optical fiber grating fabricated by point by point method

We present long period grating (LPG) fabrication and application of LPG as chemical sensor. We fabricated LPG of grating period 610μm in single mode communication grade fiber using point by point method. Here we used 12watt CO
2
laser to irradiate the fiber. The behavior of resonance wavelength of LPG was studied by immersing it in nitrate solution of concentration ranging from 10ppm to 50ppm. The results showed the linear behavior of resonance wavelength of LPG that can be used to determine the concentration of nitrate in water.