We propose and demonstrate a sensitive vector twist sensor based on a small period long period fiber grating (SP-LPFG) fabricated with a femtosecond (fs) laser. The fabricated SP-LPFG is compact in size (2.8 mm) and shows strong polarization dependent peaks in its transmission spectrum due to the vectorial behavior of high-order cladding modes. Twist sensing is realized by monitoring the polarization dependent peaks, since the polarization of input light changes with fiber twist. The proposed sensor can be interrogated by the peak intensity and wavelength, with high twist sensitivity that reaches 0.257 dB/deg and 0.115 nm/deg, respectively.
Bibliographical noteThis paper was published in Chinese Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: https://www.osapublishing.org/col/abstract.cfm?uri=col-19-9-090601. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.
Funding: This work was supported by the National Nature Science Foundation of China (Nos. 11574070, 11874126, 51803037), Leading Talents of Guangdong Province Program (No. 2016LJ06D506), and the Natural Science Foundation of
Guangdong Province, China (No. 2019A1515011229).
- fiber optical sensor
- long period fiber grating
- twist sensor