Anti-bending Long Period Grating in Embedded-core Optical Fiber

A novel anti-bending long period grating (LPG) in an embedded-core hollow optical fiber (ECOF) is proposed and experimentally demonstrated. A piece of ECOF was rotated by 180 degrees around the geometrical center of the fiber, and then it and other ECOF were aligned along the fiber core and spliced. And a LPG, the center of which is the fusion splicing point, was fabricated in the ECOF by using a high-frequency CO2 laser to form an anti-bending sensor. The dependence of the resonant peak on the bending was studied. Experimental results show that the maximum sensitivity of bending is only 0.47 nm/m(-1).