11 January 2020 Simultaneous measurement of strain and temperature based on a long-period fiber grating written on high birefringence photonic crystal fiber concatenated with a Faraday rotator mirror
Do K. Kim, Jihoon Kim, Seul-Lee Lee, Sungwook Choi, Min S. Kim, Jinsil Han, Yong W. Lee
Author Affiliations +
Abstract

Here we report simultaneous measurement of strain and temperature, carried out by incorporating a long-period fiber grating (LPFG) written on high birefringence photonic crystal fiber (HBPCF), referred to as an HBPC-LPFG, and a Faraday rotator mirror (FRM) concatenated in series with the LPFG. The HBPC-LPFG used as a sensor head was fabricated by irradiating CO2 laser pulses to unjacketed HBPCF with line-by-line technique. The HBPC-LPFG connected in series with the FRM exhibits a polarization-independent wavelength-dependent loss spectrum in its reflection spectrum, which has two resonance dips (RDs) with different cladding-mode orders, designated as RDs 1 and 2. As the two RDs in the fabricated HBPC-LPFG ended with the FRM have dissimilar cladding-mode orders, their strain sensitivities and their temperature sensitivities are different from each other. For the two RDs with resonance wavelengths of λ1  =  ∼1470.5  nm and λ2  =  ∼1495.1  nm, strain and temperature responses were investigated in an applied strain range from 0 to 1790  με (step: 179  με) and an ambient temperature range from 30°C to 95°C (step: 5°C), respectively. The strain sensitivities of the RDs 1 and 2 were measured to be approximately −0.77 and −1.07  pm  /  με at room temperature, and the temperature sensitivities of the RDs 1 and 2 were measured as ∼10.44 and ∼8.56  pm  /    °  C without applied strain, respectively. Owing to their linear and independent responses to strain and temperature, strain and temperature changes applied to the HBPC-LPFG can be simultaneously estimated from the measured wavelength shifts of the RDs 1 and 2 using their predetermined strain and temperature sensitivities.

© 2020 Society of Photo-Optical Instrumentation Engineers (SPIE) 0091-3286/2020/$28.00 © 2020 SPIE
Do K. Kim, Jihoon Kim, Seul-Lee Lee, Sungwook Choi, Min S. Kim, Jinsil Han, and Yong W. Lee "Simultaneous measurement of strain and temperature based on a long-period fiber grating written on high birefringence photonic crystal fiber concatenated with a Faraday rotator mirror," Optical Engineering 59(1), 016108 (11 January 2020). https://doi.org/10.1117/1.OE.59.1.016108
Received: 19 August 2019; Accepted: 24 December 2019; Published: 11 January 2020
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KEYWORDS
Temperature metrology

Sensors

Polarization

Birefringence

Gas lasers

Head

Mirrors

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