Design of optical sensor for detection of brininess of water

Water is the most essential element to life on Earth. Salinity is the relative concentration of salts in water. The quest to know Salinity of water is necessity, as salinity according to their respective geography may be vital or harmful. Currently determination of salt content is by chemical analysis. However, the method is time consuming and vague. In this paper a photonic crystal based optical sensor is proposed and designed to measure percentage of salinity present in the sample of water, where the optical sensor is a dielectric slab waveguide with water sample as the cladding, and photonic crystal based channel waveguide as core. The variation in salinity concentration changes the refractive index of water. The effective refractive index method has been used for the detection of the salinity concentration from (0–30%). The slab waveguide is designed and the effective refractive changed is captured. For a very small change in refractive index the effective index change is visible, making the sensor very sensitive.