METHOD AND APPARATUS FOR FORMING A BRAGG GRATING WITH HIGH INTENSITY LIGHT

摘要

A method and apparatus for forming a Bragg grating using a high intensity light includes a pair of focussed writing beams (26, 34) that simultaneously intersect and interfere with each other at a region (30) of a photosensitive optical fiber (28). The beams (26, 34) have a high intensity (e.g., at least about 500 mjoules/cm<2>) and pass through an interface medium (50) that is substantially transparent to the wavelength of the writing beams (26, 34). The medium has a thickness T set such that the intensity of the beams at the surface (56) of the medium (50) is below a surface damage intensity such that no ablations occur on the fiber (28) or the surface (56) when the fiber (28) is exposed to the beams (26, 34).