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In this paper, a novel platform for simultaneous measurement of relative humidity (RH) and temperature using dual Fabry-Perot interferometers (FPIs) based on C-shaped fiber was demonstrated. The sensor was composed by splicing two sections of C-shaped fiber between single mode fiber (SMF). Polydimethylsiloxane (PDMS) and polyvinyl alcohol (PVA) are filled in the two sections of C-shaped fibers to increase sensitivity to temperature and RH. This is the first demonstration that solid polymer materials can be added to the C-shaped fiber interferometers for sensing. In our experiment, RH sensitivities of -0.128 nm/%RH and 0.038 nm/%RH in the range of 20%RH to 45%RH, and temperature sensitivities of 0.022 nm/°C and -0.722 nm/°C in the temperature range of 15 °C to 45°C, were acquired for dual FPIs, respectively. We verified that it is possible to use the sensitivity matrix method to measure two parameters simultaneously. In addition, it has the benefits of simple structure, excellent stability and high sensitivity, and has a broad application prospect in agriculture, food processing and environmental measurement. Refereed/Peer-reviewed

Refereed/Peer-reviewed A multiplexed fiber sensor is proposed based on Fabry-Perot interferometers formed by serially splicing C-shaped and single mode fibers. We first demonstrate multiplexed refractive index sensing by independently filling and measuring sodium chloride (NaCl) solutions with different concentrations in a two-cavity system. The results show minimal cross-talk between the two interferometers. The dual-cavity interferometric sensor was then applied to biochemical sensing by utilizing polyelectrolyte layer by layer self-assembly followed by the biotin-streptavidin binding mechanism. The proposed sensor solves an important problem in biochemical sensing by providing an ability to simultaneously measure a negative control, critical for reducing false positive measurements.

A simultaneous temperature and refractive index fibre sensor based on a Fabry– Perot interferometer is demonstrated using a C-fibre and single mode fibres.

Refereed/Peer-reviewed We demonstrate a simple-to-fabricate, temperature-compensated refractive index sensor using a dual Fabry-Perot optical fiber interferometer using C-fiber. The sensor device is formed by combining two types of in-fiber interferometers, including a C-fiber Fabry-Perot interferometer and a single mode fiber (SMF) Fabry-Perot (FP) interferometer. The C-fiber is a silica capillary with an open side, which allows external liquid to directly enter the internal hole. The C-fiber interferometer is sensitive to external refractive index (1704 nm/RIU) as well as temperature (-0.196 nm/°C) due to the thermo-optic effect and thermal expansion of the C-fiber cavity, while the SMF interferometer is only sensitive to ambient temperature (0.0118 nm/°C). Thus, temperature-compensated refractive index measurement can be achieved by examining the phase shift responses of the two FP interference peaks with transfer matrix approach, solving the problem of temperature sensitivity of RI sensors due to the relatively large thermo-optic coefficient of colloidal materials and aqueous samples.