Hybrid raman and brillouin scattering in few-mode fibers
AssigneeNEC Laboratories America, Inc.
InventorsTing Wang, Yi Weng
Life of this patent
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Abstract
Methods and systems of sensing conditions in a fiber includes launching a light beam into a fiber. A first branch of scattered light is set to a mode other than a fundamental mode. A second branch of scattered light is optically filtered to remove unscattered input light. Brillouin scattered light is coherently detected on the first branch to produce a combined temperature/strain profile of the fiber. Raman scattered light on the second branch is directly detected to produce a temperature profile of the fiber. A strain profile of the fiber is determined, using a processor, based on the combined temperature/strain profile and the temperature profile.
Claims13
A hybrid Brillouin/Raman sensor, comprising:
- a mode converter configured to convert Brillouin backscattered light from a fiber to a mode other than a fundamental mode;
- an optical filter configured to separate Raman forward-scattered light from a fiber to remove unscattered input light;
- a Brillouin receiver configured to coherently detect the Brillouin backscattered light output by the mode converter and to produce a combined temperature/strain profile of the fiber;
- a Raman receiver configured to directly detect the Raman forward-scattered light output by the optical filter and to produce a temperature profile of the fiber;
- and
- a processor configured to determine a strain profile of the fiber based on the combined temperature/strain profile and the temperature profile.
A hybrid Brillouin/Raman sensor, comprising:
- a coupler configured to split backscattered light from a fiber into two paths;
- a mode converter configured to convert backscattered light on a first path to a mode other than a fundamental mode;
- an optical filter configured to separate backscattered light on a second path to remove unscattered input light;
- a Brillouin receiver configured to coherently detect the Brillouin backscattered light output by the mode converter and to produce a combined temperature/strain profile of the fiber;
- a Raman receiver configured to directly detect the Raman forward-scattered light output by the optical filter and to produce a temperature profile of the fiber;
- and
- a processor configured to determine a strain profile of the fiber based on the combined temperature/strain profile and the temperature profile.
A method for sensing conditions in a fiber, comprising:
- launching a light beam into a fiber;
- mode controlling a first branch of scattered light to a mode other than a fundamental mode;
- optically filtering a second branch of scattered light to remove unscattered input light;
- coherently detecting Brillouin scattered light on the first branch to produce a combined temperature/strain profile of the fiber;
- directly detecting Raman scattered light on the second branch to produce a temperature profile of the fiber;
- and
- determining a strain profile of the fiber, using a processor, based on the combined temperature/strain profile and the temperature profile.
Dependencies are inferred from the claim text.