Method for making long-period fiber gratings

摘要

Applicants have discovered that exposing optical fiber (20) to an electric arc produces a perturbation in its refractive index and that gratings can be made by exposing fiber to arcs (22) at a series of locations (34) along its length. In a first variation of the process, tile fiber is exposed under tension to a high current arc (>15mA) for a prolonged period of time (>2s). Using this method, long period gratings can be successfully fabricated from fiber without the use of special dopants. In a second variation, the fiber is doped and the tension is reduced. The resulting grating is optically weaker but mechanically stronger. A third variation uses hydrogen-sensitized fibers and reduced currents and times. The resulting grating is optically and mechanically strong.