Optical fiber long-period gratings for the refractometry of aqueous solutions

Refractometers are of interest for measuring concentrations of solutions, since the refractive index of a solution is proportional to its concentration. On-line continuous refractometry is important in many industrial processes, as well as for checking the concentration stability of solutions in stock. An optical fiber long-period grating is presented, which was tested for refractometry in the 1.34- 1.42 range.