We demonstrate the multiparametric monitoring of directional bending, torsion, and temperature based on helical long-period gratings (HLPGs) in a triangular four-core fiber (FCF) using CO 2 laser i…
In this paper, we demonstrate the transmission spectral and surrounding refractive index (SRI) sensing performance of long-period fiber gratings (LPFGs) at 2 μm waveband. The cladding modes operat…