Variable period amplitude grating mask and method for use
AssigneeCorning Incorporated
InventorsThomas A. Cook, Robert A. Modavis
Life of this patent
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Abstract
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.
Claims20
A variable period amplitude grating mask for a photosensitive optical waveguide, comprising:
- a plurality of elastically coupled adjacent masking regions, said mask having a period defined by a distance between said coupled adjacent masking regions, wherein said period is variable in a controlled manner as a function of a force applied to a nonstationary end of the mask in a direction of a longitudinal axis of the mask.
An amplitude grating mask for a photosensitive optical waveguide, comprising:
- a helically coiled spring having a plurality of spring coils each of which defines a masking portion, said plurality of spring coils each having a diameter sufficient to encircle a cross sectional portion of the waveguide when the waveguide is positioned along a longitudinal axis of the spring, wherein said masking portions have a variable periodicity that depends upon an extension or compression of the spring within an elastic limit of the spring.
A method for creating a photo-induced index perturbation in a photosensitive optical waveguide, comprising the steps of:
- a) masking a bare cladding section of the photosensitive waveguide with a variable period amplitude grating mask comprising multiple elastically coupled masking regions wherein the period of the masking regions is controllably varied by applying a force to a nonstationary end of the mask along a longitudinal axis of the mask, said mask period being adjusted to substantially equal a desired periodicity of the index perturbation to be photo-induced in the waveguide;
- and
- b) exposing the masked waveguide section to actinic radiation to photoinduce the index perturbation.
A method for making a long period Bragg grating in a photosensitive optical fiber waveguide, comprising the steps of:
- a) masking the fiber by positioning a bare cladding section of the fiber within the coils of a helically coiled spring along a longitudinal axis of the spring;
- b) adjusting the period of the spring to between about 10 .mu.m to 1000 .mu.m by applying a force to an end thereof, said period being approximately equal to a desired period of the Bragg grating in the fiber;
- and
- c) exposing the masked fiber to actinic radiation to photoinduce an index perturbation in the fiber.
Dependencies are inferred from the claim text.