Bend and index insensitive long period grating in progressive three layered optical fibre

摘要

A long period fibre grating written in a progressive three-layered optical fibre is shown to exhibit an attenuation band that has a very low bending sensitivity (5.1 /spl times/ 10/sup -2/ nm m) compared to normal step-index fibre, and is also insensitive to changes in the refractive index of the surrounding medium. Applications to sensing and telecommunications are discussed.