Ultrasensitive refractive index sensor with temperature insensitivity based on concatenated LPGs

Saurabh Mani Tripathi; Wojtek J. Bock; Arun Kumar; Predrag Mikulic; Katherine J. Bock

doi:10.1117/12.2026721

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20 May 2013 Ultrasensitive refractive index sensor with temperature insensitivity based on concatenated LPGs

Saurabh Mani Tripathi, Wojtek J. Bock, Arun Kumar, Predrag Mikulic, Katherine J. Bock

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Proceedings Volume 8794, Fifth European Workshop on Optical Fibre Sensors; 87940W (2013) https://doi.org/10.1117/12.2026721
Event: Fifth European Workshop on Optical Fibre Sensors, 2013, Krakow, Poland

Abstract

In this paper we report on fabrication and characterization of a refractive index sensor based on two concatenated double resonanced long period fiber gratings (LPFGs) with an inter grating space in between them. The inter grating space provides a temperature dependent extra phase difference between the core mode and the participating cladding modes, making the sensor similar to a Mach-Zehnder interferometer with its arms phase shifted. We demonstrate that by adjusting the inter grating space the thermally induced phase difference in the LPG region can be compensated, producing temperature insensitive resonance wavelengths. The interferometer is highly stable over a wide range of temperatures (20-100 °C). The measured refractive index sensitivity for aqueous solutions (1.333-1.393) is 2583.3 nm/RIU, which is highly desirable for precision sensing of biological samples.

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Saurabh Mani Tripathi, Wojtek J. Bock, Arun Kumar, Predrag Mikulic, and Katherine J. Bock "Ultrasensitive refractive index sensor with temperature insensitivity based on concatenated LPGs", Proc. SPIE 8794, Fifth European Workshop on Optical Fibre Sensors, 87940W (20 May 2013); https://doi.org/10.1117/12.2026721

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