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Fiber-Optic Refractometer Based on an Etched High-Q π-Phase-Shifted Fiber-Bragg-Grating
Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
* Author to whom correspondence should be addressed.
Received: 28 March 2013; in revised form: 20 May 2013 / Accepted: 2 July 2013 / Published: 10 July 2013
Abstract: We present a compact and highly-sensitive fiber-optic refractometer based on a high-Q p-phase-shifted fiber-Bragg-grating (pFBG) that is chemically etched to the core of the fiber. Due to the p phase-shift, a strong pFBG forms a high-Q optical resonator and the reflection spectrum features an extremely narrow notch that can be used for highly sensitivity refractive index measurement. The etched pFBG demonstrated here has a diameter of ~9.3 μm and a length of only 7 mm, leading to a refractive index responsivity of 2.9 nm/RIU (RIU: refractive index unit) at an ambient refractive index of 1.318. The reflection spectrum of the etched pFBG features an extremely narrow notch with a linewidth of only 2.1 pm in water centered at ~1,550 nm, corresponding to a Q-factor of 7.4 ´ 105, which allows for potentially significantly improved sensitivity over refractometers based on regular fiber Bragg gratings.
Keywords: fiber gratings; optical fiber sensors; optical resonators; refractive index
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Cite This Article
MDPI and ACS Style
Zhang, Q.; Ianno, N.J.; Han, M. Fiber-Optic Refractometer Based on an Etched High-Q π-Phase-Shifted Fiber-Bragg-Grating. Sensors 2013, 13, 8827-8834.
Zhang Q, Ianno NJ, Han M. Fiber-Optic Refractometer Based on an Etched High-Q π-Phase-Shifted Fiber-Bragg-Grating. Sensors. 2013; 13(7):8827-8834.
Zhang, Qi; Ianno, Natale J.; Han, Ming. 2013. "Fiber-Optic Refractometer Based on an Etched High-Q π-Phase-Shifted Fiber-Bragg-Grating." Sensors 13, no. 7: 8827-8834.