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Published on: August 30, 2012
Ultra-sensitive refractive index sensor based upon Fabry-Perot cavity directly composed of microgroove in polymethyl
Cheng Peng1, Chao Jiang1, Rui Li1
1Hubei Key Laboratory of Optoelectronic Conversion Materials and Devices, Hubei Engineering Research Center for Micronano Optoelectronic Devices and Integration, College of Physics and Electronic Science, Hubei Normal University, Huangshi, Hubei 435002, People's Republic of China.
None:
As one of the fundamental physical parameters characterizing sensor performance, the refractive index (RI) plays a significant role in the field of fiber optic sensing. This paper proposes a Fabry-Perot interferometer (FPI) RI sensor based upon an open cavity fabricated in a polymethyl methacrylate (PMMA) sheet. The sensing unit, designated FPI1, is constructed by etching a microgroove on the surface of a PMMA sheet using a CO2 laser, into which a single-mode fiber is embedded, forming an optical interference cavity open to the external environment and enabling high-sensitivity response to RI changes. To further enhance sensitivity, a Vernier effect is introduced to construct a compound sensor S1. The reference interferometer FPI2 in S1 is made by fusion splicing a single mode fiber (SMF)-capillary-SMF structure, and its free spectral range is comparable to FPI1, while remaining insensitive to RI variations. Experimental results demonstrate that the RI sensitivity of FPI1 is -1306.59 nm/RIU, whereas that of S1 reaches -12511.18 nm/RIU, corresponding to an amplification factor of ∼9.6.
