Discretization of Tilted FBGs Spectra for Sensing and Coding

Abstract

Tilted fiber Bragg gratings (TFBGs) give rise to a dense comb of cladding mode resonances for which they are appealing for high-resolution sensing. However, the interrogation of such gratings tends to be complex and expensive. As an alternative to conventional interrogation approaches, herein, we propose to discretize the TFBG spectra to form binary codes of “0” and “1” and to correlate such bits with different values of a target measurand. As an example, we demonstrate measurements of water-alcohol mixtures with TFBGs excited with randomly polarized light and interrogated over a narrow (6 nm) wavelength range. We have found that for each mixture surrounding a TFBG, a unique set of bits can be generated. As bits are the language of digital technologies and are easy to process, we believe that the approach proposed here can pave the way for a new manner of interrogating TFBGs. Moreover, the binary codes generated by discretization of TFBG spectra may allow the generation of unique visual labels (barcodes) for the identification of liquids, thereby expanding the applications of TFBGs.