Variable period amplitude grating mask and method for use

摘要

A variable period amplitude grating mask for use in making a long period Bragg grating is realized by a helically coiled spring. Stretching or compressing the spring changes the periodicity of the mask. A photosensitive optical waveguide, planar or fiber, is positioned within the spring coils along the major axis of the spring. Actinic radiation is incident on the masked waveguide, and induces an index perturbation in the waveguide having the periodicity of the mask. Different spring coil sizes and/or orientation of the waveguide with respect to the mask provide linear and nonlinear (chirped) grating periods. A device and method are described.