Optical fiber reflective filter
AssigneeCanadian Patents and Development Limited
InventorsKenneth O. Hill, Brian S. Kawasaki, Derwyn C. Johnson, Yoshimasa Fujii
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Abstract
The optical reflective filter is made from a photosensitive optical fiber having a cladding and a core including germanium. Refractive index perturbations are light induced in the fiber in the region of the guided light. The perturbations can be made to have a constant or a varying periodicity, or a series of constant periodicities. The filters are made from single mode or low order mode fibers having germanium doped silica or germania cores. The center frequency for reflective band or bands has a wavelength in the 400 nm to 550 nm range. The reflective band or bands in the filter can be shifted by stretching the filter.
Claims17
An optical refective filter comprising a photosensitive optical fiber having a cladding and a core including germanium and having a minimum numerical aperture of 0.1 wherein refractive index perturbations are light induced in the region of the guided light.
A method of making an optical reflective filter from a photosensitive fiber having a cladding and a core comprising the steps of:
- (a) transmitting a predetermined coherent light beam through the fiber in one direction;
- and
- (b) reflecting the light beam back through the fiber in the other direction to interfere with the launched beam to form a stable interference pattern so as to produce refractive index perturbations in the fiber.
Dependencies are inferred from the claim text.