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US 5,857,053 AGranted
Optical fiber filter
AssigneeLucent Technologies Inc.
InventorRichard Thomas Kane
Life of this patent
Estimating the term…
Abstract
The present applicant has discovered that an optical filter can be made by etching away part of the cladding of a depressed-cladding fiber. The etching produces a section of fiber having a double peak in the index profile. In a low index medium such as air, the remaining cladding portion guides radiation at certain wavelengths. This radiation is extracted from the radiation in the fiber core.
Claims8
An optical fiber filter for removing light of a peak wavelength from a fiber core comprising:
- a length of optical fiber comprising a core having a first refractive index, a first cladding region adjacent the core having a second refractive index lower than the core and a second cladding region adjacent said first cladding region having a third refractive index lower than the core but higher than the first cladding region,
- said second cladding region including a length of reduced thickness, the outer surface of said second cladding region in contact with a medium having a refractive index lower than the second cladding whereby said second cladding region acts as a concentric ring waveguide spaced from the core for propagating light of said peak wavelength.
A method for making an optical fiber filter for removing light of a peak wavelength from a fiber core comprising the steps of:
- providing a length of optical fiber comprising a core having a first refractive index, a first cladding region adjacent said core having a second refractive index lower than the core and a second cladding region adjacent the first cladding region having a third refractive index lower than the core but higher than the first cladding region,
- etching away along a length of said fiber a portion of the thickness of said second cladding to produce a length of reduced thickness;
- immersing said length of reduced thickness in a medium having a refractive index lower than said second cladding, said second cladding in contact with said medium, whereby said second cladding acts as a concentric ring waveguide spaced from the core for propagating light of said peak wavelength.
Dependencies are inferred from the claim text.