Method and apparatus for writing apodized patterns
AssigneeZygo Corporation
InventorPeter J. De Groot
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Abstract
In some aspects, the invention relates to methods and systems for creating apodized periodic structures, such as apodized gratings in fibers. To create the periodic structures, a photosensitive medium is exposed to a spatially-varying radiation pattern. During the exposure, the position of the radiation pattern can oscillate with the respect to the photosensitive medium, thereby changing the average local refractive index of the medium. These methods and systems may be used to create regular structures in any appropriate medium, such as doped glasses and photosensitive polymers.
Claims36
A method for writing apodized fiber Bragg gratings in an optical fiber having a photosensitive core, the method comprising:
- exposing a first portion of the photosensitive core to an interference pattern for a first period to cause an amplitude modulation in the refractive index of the first portion;
- and
- exposing the first portion to the interference pattern for a second period while oscillating the position of the radiation pattern with respect to the photosensitive core to change the average refractive index modulation of the first portion of the medium,
- wherein the first and second periods are selected so that the first portion comprises a portion of an apodized fiber Bragg grating.
A method, comprising:
- exposing a first portion of a photosensitive medium to a radiation pattern for a first period to cause an amplitude modulation in the refractive index of the first portion;
- and
- exposing the first portion to the radiation pattern for a second period while oscillating the position of the radiation pattern with respect to the photosensitive medium to change the average refractive index of the first portion of the medium.
An apparatus, comprising:
- an exposure system configured to illuminate a target with an interference pattern, the exposure system comprising an optical element and a dither stage which is capable of selectively dithering the optical element to cause the position of the interference pattern at the target to oscillate;
- a stage for positioning a photosensitive medium at the target;
- an electronic controller, in communication with the exposure system, which during operation causes the exposure system to expose a first portion of the photosensitive medium at the target to the interference pattern for a first period without dithering the optical element and for a second period dithering the an optical element.
Dependencies are inferred from the claim text.