MMI fiber optic refractometer with universal pH indicator coating

Abstract

In this paper we show the preliminary results about fabrication of an optical fiber refractometer based on multimode interference effects (MMI) provided with Universal pH Indicator coating. The layer, deposited by coating dip-coating technique, allows increase the refractometer sensitivity which is around 344.5054 nm/RIU in a range of 1.333 to 1.4223. Highly repetitive and reversible refractometer have been achieved using a simple fabrication process. The device shown offers the possibility to be used as instrument to identify substances included aggressive liquids as gasoline.