Fiber Bragg Granting Sensor for Detection of Nitrate Concentration in Water

The concentrations of chemical species in drinking water are of great interest. We demonstrated etched fiber Bragg grating (FBG) as a concentration sensor for nitrate by analyzing the Bragg wavelength shift with concentration of chemical solution. The FBG is fabricated by phase mask technique on single mode Ge-B co-doped photosensitive fiber. Sensitivity of FBGs to the surrounding solution concentration can be enhanced by reducing diameter of the cladding with 40 % HF solution. The maximum sensitivity achieved is 1.322 10-3 nm/ppm. The overall shift of Bragg wavelength is of the order of 6.611 10-2 nm for 10 to 50 ppm concentration. Copyright © 2011 IFSA