Tuning Cladding-Mode Propagation Mechanisms in Liquid Crystal Long-Period Fiber Gratings

This paper presents the latest developments in the field of liquid crystal long-period fiber gratings (LC-LPFGs). The new design of LC-LPFG proposed here has unique propagation properties stemming from the use of special low-birefringence LC mixtures as an “active” external layer on the LPFG. In specific temperature regions, the refractive indices of these LC mixtures are below the refractive index of fused silica. This feature makes it possible to dynamically control the propagation mechanisms of the cladding modes. As a result, a high-efficiency thermal and/or electric tuning of LC-LPFGs could be achieved.