Abstract: Local birefringence is determined from a scatter signature of a birefringent waveguide. Four copies of a Rayleigh scatter time delay domain signature of the fiber are collected from two orthogonal polarization received states and from two orthogonal polarization launched states to form a Jones transfer matrix. Obtaining the Jones transfer matrix for the waveguide eliminates the need to align the instrument polarization launch state to the birefringence axes. Birefringence is determined from an autocorrelation of a polarization state averaged function calculated from the transfer matrix terms. Alternatively, the transfer matrix is rotated until fast and slow eigenvectors are separated, fast and slow amplitude functions are generated, and a cross-correlation is performed on the fast and slow amplitude functions in order to determine the birefringence.

Abstract: To sense the shape of a multicore optical fiber sensor, light reflected in a center and two or more helixed outer cores of the optical fiber sensor is measured, and phases associated with strain in the center and helixed outer cores is tracked along the length of the fiber sensor. Further, a wobble signal indicative of a variation in the spin rate of the fiber sensor is determined. Based on the tracked phases and the wobble signal, the fiber shape is computed.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: Local birefringence is determined from a scatter signature of a birefringent waveguide. Four copies of a Rayleigh scatter time delay domain signature of the fiber are collected from two orthogonal polarization received states and from two orthogonal polarization launched states to form a Jones transfer matrix. Obtaining the Jones transfer matrix for the waveguide eliminates the need to align the instrument polarization launch state to the birefringence axes. Birefringence is determined from an autocorrelation of a polarization state averaged function calculated from the transfer matrix terms. Alternatively, the transfer matrix is rotated until fast and slow eigenvectors are separated, fast and slow amplitude functions are generated, and a cross-correlation is performed on the fast and slow amplitude functions in order to determine the birefringence.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

Abstract: An optical fiber includes primary optical core(s) having a first set of properties and secondary optical core(s) having a second set of properties. The primary set of properties includes a first temperature response, and the secondary set of properties includes a second temperature response sufficiently different from the first temperature response to allow a sensing apparatus when coupled to the optical fiber to distinguish between temperature and strain on the optical fiber. A method and apparatus interrogate an optical fiber having one or more primary optical cores with a first temperature response and one or more secondary optical cores with a second temperature response. Interferometric measurement data associated with each primary and secondary optical core are detected when the optical fiber is placed into a sensing position.

Abstract: An optical fiber includes multiple optical waveguides configured in the fiber. An interferometric measurement system mitigates or compensates for the errors imposed by differences in a shape sensing optical fiber's response to temperature and strain. A 3-D shape and/or position are calculated from a set of distributed strain measurements acquired for a multi-core optical shape sensing fiber that compensates for these non-linear errors using one or more additional cores in the multicore fiber that react differently to temperature changes than the existing cores.

Abstract: An optical fiber includes primary optical core(s) having a first set of properties and secondary optical core(s) having a second set of properties. The primary set of properties includes a first temperature response, and the secondary set of properties includes a second temperature response sufficiently different from the first temperature response to allow a sensing apparatus when coupled to the optical fiber to distinguish between temperature and strain on the optical fiber. A method and apparatus interrogate an optical fiber having one or more primary optical cores with a first temperature response and one or more secondary optical cores with a second temperature response. Interferometric measurement data associated with each primary and secondary optical core are detected when the optical fiber is placed into a sensing position.

Abstract: An optical fiber includes multiple optical waveguides configured in the fiber. An interferometric measurement system mitigates or compensates for the errors imposed by differences in a shape sensing optical fiber's response to temperature and strain. A 3-D shape and/or position are calculated from a set of distributed strain measurements acquired for a multi-core optical shape sensing fiber that compensates for these non-linear errors using one or more additional cores in the multicore fiber that react differently to temperature changes than the existing cores.

Abstract: A twisted, multicore fiber communicates light input to each core to an output. The twisting mitigates relative time delays of the input light traveling through each of the cores in the multicore fiber to the output caused by bending of that multicore fiber. An example application is in an optical network that includes an optical input terminal and an optical sensor connected by a twisted multicore connecting fiber. One example of twisted multicore optical fiber is helically-wrapped, multicore fiber.

Abstract: A twisted, multicore fiber communicates light input to each core to an output. The twisting mitigates relative time delays of the input light traveling through each of the cores in the multicore fiber to the output caused by bending of that multicore fiber. An example application is in an optical network that includes an optical input terminal and an optical sensor connected by a twisted multicore connecting fiber. One example of twisted multicore optical fiber is helically-wrapped, multicore fiber.

Abstract: An interferometric measurement system includes a spun optical fiber including multiple optical waveguides configured in the fiber. Interferometric detection circuitry detects measurement interferometric pattern data associated with each of the multiple optical waveguides when the optical fiber is placed into a bend. Data processing circuitry determines compensation parameters that compensate for variations between an optimal configuration of the multiple optical waveguides in the fiber and an actual configuration of multiple optical waveguides in the fiber. The compensation parameters are stored in memory for compensating subsequently-obtained measurement interferometric pattern data for the fiber.