| 摘要 |
PROBLEM TO BE SOLVED: To form an evanescent optical sensor as a coil of either optical fiber or microfiber for a "small" optical sensor. SOLUTION: By coiling the fiber/microfiber, the overall size of the sensor is significantly reduced when compared to "straight path" prior art fiber sensors, yet exhibits a similar degree of sensitivity. In operation, an optical signal is coupled into a fiber coil that has been immersed in an ambient to be analyzed. The use of a coil configuration results in creating a plurality of whispering gallery modes (WGMs) that will propagate along the coil by reflecting from the surface of the curved fiber/microfiber forming the coil. The interference between these modes will be modified as a function of the properties of the ambient environment within which the coil is immersed. Environmental changes cause variations in the optical length of the coil as "seen" by the various modes, and the interference of the modes is analyzed by studying the transmission spectrum at the output of the coil. COPYRIGHT: (C)2011,JPO&INPIT |
