All-fiber, low-cost single-point and quasi-distributed evanescent field temperature sensors with extended temperature measurement range, based on standard telecommunication graded index fibers

Fiber-optic single-point and quasi-distributed evanescent temperature sensors recoated with a blend of poly(methyl methacrylate) and poly(vinylidene fluoride) are proposed. Solid cladding enables the construction of small-size, low-cost, relatively wide-range and fast-response temperature sensors. The diameter of the sensor (foes not exceed the dimensions of the original optical fiber, while the response time of the sensor is 7.4 ms. Different mass ratios of polymers in the blend enable fine tuning of the applied cladding's refractive index. This allows the construction of sensors for different temperature ranges, while the application of all-silica graded-index multimode fibers enables the construction of quasi-distributed sensor systems with considerably reduced cross talk. (c) 2008 Optical Society of America.