Process for preparing an optical fiber sensor with enhanced sensitivity
First Claim
1. A process for preparing an optical fiber having at least one long period grating with enhanced sensitivity, the process comprising the steps of:
- a) providing a length of optical fiber having a refractive index profile, and wherein the optical fiber supports a core mode and cladding modes for a range of operational wavelengths;
b) identifying group indices for the core mode and the cladding modes for a specific wavelength wherein the group indices are equal to each other; and
c) writing a long period grating in the optical fiber wherein the long period grating has a period defined by the group indices and wherein the long period grating couples light from the core mode to a cladding mode proximate to where the group indices are equal.
5 Assignments
0 Petitions
Accused Products
Abstract
A process for preparing an optical fiber having at least one long period grating with enhanced sensitivity is provided. A length of optical fiber having a refractive index profile is provided. The optical fiber supports a core mode and cladding modes for a range of operational wavelengths. Group indices are identified for the core mode and the cladding modes for a specific wavelength wherein the group indices are equal to each other. A long period grating is written in the optical fiber. The long period grating has a grating defined by the group indices and it couples light from the core mode to a cladding mode proximate to where the group indices are equal. The optical fibers prepared by the present invention may be used for measuring an environmental perturbation where high sensitivity is required.
-
Citations
15 Claims
-
1. A process for preparing an optical fiber having at least one long period grating with enhanced sensitivity, the process comprising the steps of:
-
a) providing a length of optical fiber having a refractive index profile, and wherein the optical fiber supports a core mode and cladding modes for a range of operational wavelengths; b) identifying group indices for the core mode and the cladding modes for a specific wavelength wherein the group indices are equal to each other; and c) writing a long period grating in the optical fiber wherein the long period grating has a period defined by the group indices and wherein the long period grating couples light from the core mode to a cladding mode proximate to where the group indices are equal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A process for preparing an optical fiber have at least one long period grating with enhanced sensitivity, the process comprising the steps of:
-
a) providing a length of optical fiber having a refractive index profile, and wherein the optical fiber supports a core mode and cladding modes for a range of operational wavelengths; b) calculating effective indices of the core mode and the cladding modes; c) calculating a phase match condition of a long period grating; d) generating characteristic modal curves; e) identifying a modal cusp by plotting wavelength of light passing through the optical fiber versus grating period and identifying a change in slope of the plot; and f) writing a long period grating in the optical fiber wherein the long period grating has a period defined by the group indices and wherein the long period grating couples light from the core mode to a cladding mode proximate to the modal cusp. - View Dependent Claims (11)
-
-
12. A process for measuring an environmental perturbation, the process comprising the steps of:
-
a) providing an optical fiber having at least one long period grating with enhanced sensitivity, each long period grating having a period defined by group indices and having two coupling points into a single cladding mode, wherein each coupling point has a specific wavelength; b) exposing the optical fiber to a perturbation in an environment wherein the exposure causes a change in the wavelength of each coupling point; and c) measuring a separation difference in the wavelengths of each coupling point. - View Dependent Claims (13, 14)
-
-
15. A process for measuring refractive index, the process comprising the steps of:
-
a) providing an optical fiber having at least one long period grating with enhanced sensitivity, each long period grating having a period defined by group indices and having two coupling points into a single cladding mode, wherein each coupling point has a specific wavelength; b) exposing the optical fiber to a refractive index change, wherein the exposure causes a change in the wavelength of each coupling point; and c) measuring a separation difference in the wavelengths of each coupling point.
-
Specification