Nanomaterial-Functionalized Tilted Fiber Gratings for Optical Modulation and Sensing

The tilted fiber grating (TFG) is a special grating whose grating planes are slanted or blazed relative to the fiber axis. These tilts in the planes break the cylindrical symmetry of the fiber, strongly enhance the light coupling from the fiber core to cladding, and resonantly excite a large number of cladding modes. Then, the TFGs with rich spectral information and strong evanescent field leaking out open up a multitude of opportunities for the enabled light-matter interaction by functionalizing their surface with nanomaterials. In this review, we briefly analyze the architectures, coupling mechanisms, spectral properties, and implementations of different TFGs, including weakly tilted Bragg grating with small tilt angle, radiated TFG with 45° tilt angle, excessively TFG with large tilt angle, etc. Further, the sensing enhancement and spectral modulation by integrating layered nanomaterials on TFGs are discussed, which could be considered as a promising strategy to break the limitation of fiber's one-dimensional structure and promote the light-matter interaction for enhanced and extended applications in optical parameter modulation and sensing.