Array topologies for implementing serial fiber Bragg grating interferometer arrays
First Claim
1. An interferometer array, comprising:
- a plurality of interferometer sub-arrays, each sub-array including a plurality of interferometers, each interferometer being implemented with a respective pair of fiber Bragg gratings and a sensing length of optical fiber positioned between said respective pair of fiber Bragg gratings, said fiber Bragg gratings in each respective pair of fiber Bragg gratings having the same characteristic wavelength that is different from the characteristic wavelength of every other pairs of fiber Bragg gratings in said sub-array; and
sub-array interconnection means interconnecting said sub-arrays to one another to form said interferometer array, said sub-array interconnection means including optical signal delay means for delaying signals from one pair of fiber Bragg gratings in one sub-array with respect to each pair of fiber Bragg gratings in other sub-arrays having the same characteristic wavelength as the characteristic wavelength of the one pair of fiber Bragg gratings;
wherein said optical signal delay means of said sub-array interconnections means minimizes the common-wavelength crosstalk between the interferometers in the interferometer array.
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Abstract
An interferometer array includes a plurality of interferometer sub-arrays, each sub-array including a plurality of interferometers. Each interferometer in a sub-array is implemented with a respective pair of fiber Bragg gratings and a sensing length of optical fiber positioned between the respective pair of fiber Bragg gratings. The fiber Bragg gratings in each respective pair of fiber Bragg gratings have the same characteristic wavelength that is different from the characteristic wavelength of every other pair of fiber Bragg gratings in the sub-array. The sub-arrays are interconnected to minimize the common-wavelength crosstalk between the sensors in the overall interferometer array. In one embodiment, the sub-arrays are connected in series along a common length of optical fiber such that the maximum common-wavelength crosstalk is limited by the number of sub-arrays connected in series. In a second embodiment of the invention, branches are interconnected to a common input/output optical fiber via optical couplers, and each branch has one or more sub-arrays connected in series. The common-wavelength crosstalk is limited by the number of arrays in each sub-array. In a third embodiment of the invention, branches are interconnected between an input optical fiber and an output optical fiber via optical couplers, and each branch has one or more sub-arrays connected in series. Optical signal delay elements are positioned in the input optical fiber to incrementally increase the delay experienced by an input optical signal before it reaches each successive branch connected to the input optical fiber. Therefore, the return optical signals from each sub-array in a branch are separated in time from the return optical signals from the sub-arrays in the other branches.
97 Citations
17 Claims
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1. An interferometer array, comprising:
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a plurality of interferometer sub-arrays, each sub-array including a plurality of interferometers, each interferometer being implemented with a respective pair of fiber Bragg gratings and a sensing length of optical fiber positioned between said respective pair of fiber Bragg gratings, said fiber Bragg gratings in each respective pair of fiber Bragg gratings having the same characteristic wavelength that is different from the characteristic wavelength of every other pairs of fiber Bragg gratings in said sub-array; and sub-array interconnection means interconnecting said sub-arrays to one another to form said interferometer array, said sub-array interconnection means including optical signal delay means for delaying signals from one pair of fiber Bragg gratings in one sub-array with respect to each pair of fiber Bragg gratings in other sub-arrays having the same characteristic wavelength as the characteristic wavelength of the one pair of fiber Bragg gratings; wherein said optical signal delay means of said sub-array interconnections means minimizes the common-wavelength crosstalk between the interferometers in the interferometer array. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An optical system, comprising:
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a light source for providing an input optical signal; and an interferometer array connected to said light source by an optical fiber, said interferometer array including; (a) a plurality of interferometer sub-arrays, each sub-array including a plurality of interferometers, each interferometer being implemented with a respective pair of fiber Bragg gratings and a sensing length of optical fiber positioned between said respective pair of fiber Bragg gratings, said fiber Bragg gratings in each respective pair of fiber Bragg gratings having the same characteristic wavelength that is different from the characteristic wavelength of every other pair of fiber Bragg gratings in said sub-array; and (b) sub-array interconnection means interconnecting said sub-arrays to one another to form said interferometer array, said sub-array interconnection means including optical signal delay means for delaying signals from one pair of fiber Bragg gratings in one sub-array with respect to each pair of fiber Bragg gratings in other sub-arrays having the same characteristic wavelength as the characteristic wavelength of the one pair of fiber Bragg gratings; (c) wherein said optical signal delay means of said sub-array interconnection means minimizes the common-wavelength crosstalk between the interferometers in the interferometer array; wherein each fiber Bragg grating is responsive to said input optical signal for providing a primary optical return signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification