摘要 |
The present invention pertains to a sensor for detecting species concentrations in an analyte. The sensor includes an optical fiber. The optical fiber has a core and an intermediate dielectric layer circumferentially surrounding the core. The core has an index of refraction which is greater than the index of refraction of the intermediate dielectric layer. The intermediate dielectric layer has an index of refraction which is greater than the index of refraction of the analyte. The intermediate dielectric layer is of a thickness such that there is a minimal decay of an evanescent wave passing through the intermediate dielectric layer. Moreover, the intermediate dielectric layer is also unreactive to light. The sensor also includes a modal selector disposed to launch light into the core of the optical fiber into a desired mode or modes.
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