Polarization-dependent refractometer for discrimination of temperature and ambient refractive index.
ABSTRACT Transmission characteristics of polarization-dependent refractometer based on a surface long-period grating (SLPG) inscribed in a D-shaped photonic crystal fiber (PCF) are investigated. The birefringence of SLPG produces the separation of transmission spectra for TE and TM polarization modes. We also measure the sensitivities of PCF-based SLPG to temperature and external refractive index change depending on the input polarization states. The SLPG-based sensor exhibits different temperature and ambient index sensitivities corresponding to TE and TM polarization modes. Therefore, the SLPG inscribed in D-shaped PCFs can effectively discriminate temperature and ambient index sensitivities.
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- "This result shows that the sensor has a rather strong temperature dependence. This temperature-dependent resonance peak shift is expected and it has been discussed in previously published work , . However since the resonant peak monotonically redshifts with temperature, it is possible to apply a correction factor to mitigate the temperature induced errors. "
ABSTRACT: An all-fiber refractive index (RI) sensor with a simple configuration of periodical tapers is proposed and investigated experimentally. The proposed fiber RI sensor consists of a small core fiber sandwiched between two standard singlemode fibers, with tapers periodically fabricated along the small core fiber using a focused CO2 laser beam. Such a structure can be used for RI sensing by measuring the dip wavelength shift of the multimode interference within the small core fiber cladding. An average sensitivity of 226.6 nm/RIU (RI Unit) has been experimentally achieved in the RI range from 1.33 to 1.38. The refractometer is sensitive to temperature and an experimental investigation of this sensitivity is presented. It is found that the peak shift response has a linear variation with temperature; therefore, temperature dependence can be mitigated by a suitable RI correction process. The proposed RI sensor benefits from simplicity and low cost and achieves a competitive sensitivity compared with other existing fiber-optic sensors.IEEE Sensors Journal 01/2013; 13(1-1):180-185. DOI:10.1109/JSEN.2012.2216865 · 1.85 Impact Factor
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ABSTRACT: A novel fiber-optic refractometer is proposed and demonstrated to achieve temperature- and axial strain-compensated refractive index measurement using highly sensitive outer-cladding modes in a tapered bend-insensitive fiber based Mach-Zehnder interferometer. Peak wavelength shifts associated with different spatial frequency peaks are calibrated to obtain a wavelength-related character matrix λMRI,T,ε for simultaneous measurement of multiple environmental variables. A phase-related character matrix ΦMRI,T,ε is also acquired by direct determination of refractive index, temperature, and axial strain induced phase shifts of the corresponding sensing modes.Optics Express 04/2013; 21(8):9996-10009. DOI:10.1364/OE.21.009996 · 3.53 Impact Factor
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ABSTRACT: A solution refractive index (SRI) and temperature simultaneous measurement sensor with intensity-demodulation system based on matching grating method were demonstrated. Long period grating written in a photonic crystal fiber (LPG-PCF), provides temperature stable and wavelength dependent optical intensity transmission. The reflective peaks of two fiber Bragg gratings (FBGs), one of which is etched then sensitive to both SRI and temperature, another (FBG2) is only sensitive to temperature, were located in the same linear range of the LPG-PCF's transmission spectrum. An identical FBG with FBG2 was chosen as a matching FBG. When environments (SRI and temperature) change, the wavelength shifts of the FBGs are translated effectively to the reflection intensity changes. By monitoring output lights of unmatching and matching paths, the SRI and temperature were deduced by a signal processing unit. Experimental results show that the simultaneous refractive index and temperature measurement system work well. The proposed sensor system is compact and suitable for in situ applications at lower cost.The Review of scientific instruments 07/2013; 84(7):075004. DOI:10.1063/1.4816155 · 1.58 Impact Factor