Resonance peak shift and dual peak separation of long-period fiber gratings for sensing applications

Abstract

The systematic analysis of the relationship among the transmission characteristics of long-period fiber gratings, the initial coupling strength, and the fluence of the postexposure W beam are discussed. The UV postexposure allows for adjustment of the peak depth depending on the initial coupling strength while red-shifting the resonance wavelength, Dual peak separation can occur for high-order cladding modes, and its application to sensing of the bending curvature, transverse load, and external refractive index are described.