Compact Long Period Fiber Grating Based on Periodic Micro-Core-Offset

Abstract

A novel long period fiber grating (LPFG) fabrication method has been proposed and experimentally demonstrated. This method is based on periodically arranging micro-core-offsets (MCOs) along an optical fiber. The MCO is formed by splicing two fiber ends with a purposed lateral offset, which results in a strong refractive index modulation by changing the fiber geometry. The lateral offset value of the MCO can be adjusted to control the coupling constant and grating length. With a lateral offset value of 3.5 μm, a very short MCO-LPFG with a length of 1.09 mm can be formed by only three MCOs. Several MCO-LPFGs with different parameters have been fabricated and the sensing characteristics of the MCO-LPFGs have been discussed as well.