High resolution refractive index sensing with cladded multimode tapered optical fibre

A new fibre-optic refractive index sensor is presented. It is based on the radiation losses introduced by the sample medium in a cladded multimode tapered fibre. A simple light transmission measurement setup is used to test some samples. It is demonstrated that the sensor is suitable for measuring RI in the range 1.36 to 1.46, as well as RI changes below 10/sup -4/.