Optimization of a Long Period Grating Distal Probe for Temperature and Refractive Index Measurement

Alwis, Lourdes; Sun, Tong; Grattan, Kenneth T.V

Abstract

Long Period Gratings (LPG)-based sensors are widely used due to their higher sensitivity to various measurands. However, a single grating based LPG sensor system has the disadvantage of the probe being used in transmission mode due to the broad bandwidth of the attenuation bands formed by propagation mode coupling between core-cladding modes and hence a difficulty in use when acting as a typical sensor probe. To overcome these limitations, a Michelson Interferometer type sensor configuration is considered using a LPG grating pair formed by coating a mirror at the distal end of the LPG. This sensor configuration is more convenient and able to overcome the limitations of the single LPG sensor with the shifts in the attenuation bands thus easily detectable. To configure the probe in the most suitable way, a series of tests has been carried out to determine the optimum distance between the LPG and the mirror coating for a typical grating of period 250 μm. The sensor is then used for temperature and refractive index calibration and the results presented show the detection scheme of the sensor probe thus optimized.

• Presentation Conference Type: Conference Paper (Published)
• Conference Name: EuroSensors 2012
• Start Date: Sep 9, 2012
• End Date: Sep 12, 2012
• Acceptance Date: Jun 1, 2012
• Publication Date: 2012
• Deposit Date: Feb 4, 2020
• Publicly Available Date: Feb 17, 2020
• Journal: Procedia Engineering
• Print ISSN: 1877-7058
• Publisher: Elsevier
• Volume: 47
• Pages: 718-721
• Book Title: 26th European Conference on Solid-State Transducers, EUROSENSOR 2012
• DOI: https://doi.org/10.1016/j.proeng.2012.09.248
• Keywords: Long Period Grating (LPG); Self Interfering Long Period Grating (SILPG); Michelson Interferometer
• Public URL: http://researchrepository.napier.ac.uk/Output/947725