Optical fiber having enhanced separation of higher-order modes
AssigneesLucent Technologies Inc., Fitel USA Corp.
InventorsSteven Golowich, Siddharth Ramachandran
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Abstract
A new annular-core optical fiber is useful, inter alia, for stabilizing the behavior of an optical attenuator based on a Long Period Grating (LPG) against fluctuations in the polarization of the fundamental optical signal. The fiber dimensions and Δn are selected such that when a LPG of some period is used to couple fundamental-mode radiation in the fiber into higher-order modes, the wavelength of peak coupling into an HE mode is removed by at least 30 nm from the wavelength of peak coupling into the nearer of a TE mode or a TM mode.
Claims5
An optical fiber comprising central and cladding regions having a first refractive index and having respectively an outer radius r1 and an inner radius r2, and juxtaposed between said regions an annular region having a second refractive index elevated above the first refractive index by an amount Δn, wherein:
- r1, r2, and Δn are selected such that when a long-period grating (LPG) of some period is used to couple fundamental-mode radiation in the fiber into higher-order modes of some radial order m, the wavelength of peak coupling into an HE2m mode is removed by at least 30 nm from the wavelength of peak coupling into the nearer of a TE0m mode or a TM0m mode.
An optical fiber comprising central and cladding regions having a first refractive index and having respectively an outer radius r1 and an inner radius r2, and juxtaposed between said regions an annular region having a second refractive index elevated above the first refractive index by an amount Δn, wherein r1, r2, and Δn are selected such that over a spectral range of at least 30 nm, a long-period grating matched to said spectral range can extract fundamental-mode radiation from the fiber independently of fluctuations in the state of polarization of the fundamental-mode radiation.
Dependencies are inferred from the claim text.