A method for refractive index measurement of a liquid in a suspended core fiber using Brillouin dynamic grating

A novel method is proposed to measure the refractive index change of a liquid around a fiber using a dynamic grating generated by stimulated Brillouin scattering. Two pump waves are used to generate a dynamic grating along a polarization-maintaining fiber. The grating is then read by a probe wave. It is shown numerically that the frequency deviation of the pump and probe waves depends on the refractive index of liquid around the fiber. We consider three- and four-hole suspended core fibers, in which one or two holes are filled with liquid, and investigate the change in the birefringence and the frequency deviation of the Brillouin dynamic grating due to the variation of the refractive index of liquid. The effects of fiber parameters on the sensitivity of frequency deviation as a function of liquid refractive index are discussed. We predict that a resolution of can be obtained using this method.