Dispersion measurement of liquids with a fiber optic probe based on a bi-functional lensed photonic crystal fiber

► Fiber optic extrinsic cavity sensor based on lensed photonic crystal fiber. ► Long cavity of about 1620 μm suitable for characterizing liquids. ► Analytical method of obtaining dispersion from spectral interferometry. ► Experimentally found that dispersion of salt water is linear at low concentrations.