Refractometric sensor based on all-fiber coaxial Michelson interferometers

摘要

All-fiber coaxial Michelson interferometers are compact and very stable interferometers that can be dipped directly into water solutions for chemical and biological sensing. The sensitivity of the cladding mode to the surrounding medium can be exploited to use the interferometer as a compact fiber refractometer. Several interferometers have been fabricated and characterized as glucose sensors. A first series of devices were designed to work at 1550 nm, while a second series was prepared to work at 850 nm. Thus, the second series of interferometers enables the use of compact, robust and low cost optical spectrum analyzers. In our present experiments, the length of the fiber that forms the interferometer was within the range 1-10 cm. When the shift of the spectrum maxima were measured as a function of the glucose concentration, a slope of 350 pm/% was achieved. The use of the 850 nm sensor heads as a portable sensor system to monitor sewage treatment plants is shown.