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 multiple optical cores configured in the fiber including a set of primary cores and an auxiliary core. An interferometric measurement system uses measurements from the multiple primary cores to predict a response from the auxiliary core. The predicted auxiliary core response is compared with the actual auxiliary core response to determine if they differ by more than a predetermined amount, in which case the measurements from the multiple primary cores may be deemed unreliable.

Abstract: A fiber includes M primary cores and N redundant cores, where M an integer is greater than two and N is an integer greater than one. Interferometric circuitry detects interferometric pattern data associated with the M primary cores and the N redundant cores when the optical fiber is placed into a sensing position. Data processing circuitry calculates a primary core fiber bend value for the M primary cores and a redundant core fiber bend value for the N redundant cores based on a predetermined geometry of the M primary cores and the N redundant cores in the fiber and detected interferometric pattern data associated with the M primary cores and the N redundant cores. The primary core fiber bend value and the redundant core fiber bend value are compared in a comparison. The detected data for the M primary cores is determined reliable or unreliable based on the comparison. A signal is generated in response to an unreliable determination.

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 system and method are used for an optical fiber having a core multiple, closely-spaced optical gratings written along the core that create a repeated pattern in the core. A memory stores predetermined reference reflection data and measurement reflection data determined for a length of the core detected from interferometric patterns corresponding to scatter reflections received from the core. Data processing circuitry reduces or removes from the measurement reflection data information that corresponds to reflections due to the repeated pattern in the core to produce filtered measurement data. One or more portions of the filtered measurement data is/are correlated with one or more portions of the reference reflection data to produce multiple correlation values. The greatest of the multiple correlation values is determined, and a location along the fiber corresponding to the greatest correlation value is identified.

Abstract: An optical force sensor along with an optical processing apparatus and method are disclosed. The optical force sensor includes an optical fiber, a core included in the optical fiber, an instrument including the optical fiber, the instrument having a distal region, and a tubular structure encasing an end of the optical fiber and secured to the first conduit at the distal region of the instrument. When an optical interferometric system is coupled to the optical fiber, it processes reflected light from a portion of the core included within the tubular structure that does not include Bragg gratings to produce a measurement of a force present at the distal region of the instrument.

Abstract: A system and method are used for an optical fiber having a core multiple, closely-spaced optical gratings written along the core that create a repeated pattern in the core. A memory stores predetermined reference reflection data and measurement reflection data determined for a length of the core detected from interferometric patterns corresponding to scatter reflections received from the core. Data processing circuitry reduces or removes from the measurement reflection data information that corresponds to reflections due to the repeated pattern in the core to produce filtered measurement data. One or more portions of the filtered measurement data is/are correlated with one or more portions of the reference reflection data to produce multiple correlation values. The greatest of the multiple correlation values is determined, and a location along the fiber corresponding to the greatest correlation value is identified.

Abstract: Example embodiments add an optical amplifier to an multi-channel, continuously swept OFDR measurement system, adjust amplified swept laser output power between rising and falling laser sweeps, and/or utilize portions of a laser sweep in which OFDR measurements are not typically performed to enhance the integrity of the OFDR measurement system, improve the performance and quality of OFDR measurements, and perform additional measurements and tests.

Abstract: Shape sensing with a multi-core fiber can achieve high accuracy as well as accommodate small bend radii by measuring signals with peripheral waveguide cores placed at multiple different radial distances from the center axis of the fiber, and computing strain metrics from signals of cores selected based on the respective radial distances and a determination of whether the waveguide cores have strained out of range.

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: Example embodiments add an optical amplifier to an multi-channel, continuously swept OFDR measurement system, adjust amplified swept laser output power between rising and falling laser sweeps, and/or utilize portions of a laser sweep in which OFDR measurements are not typically performed to enhance the integrity of the OFDR measurement system, improve the performance and quality of OFDR measurements, and perform additional measurements and tests.

Abstract: An interferometric measurement system measures a spun optical fiber sensor that includes multiple optical cores configured in the fiber sensor. A calibration machine includes a calibration fixture having known dimensions, one or more automatically controllable actuators for wrapping the fiber sensor starting at one end of the fiber sensor onto a calibration fixture having known dimensions, and an actuator controller configured to control the one or more actuators with actuator control signals. Interferometric detection circuitry, coupled to the actuator controller and to the other end of the fiber sensor, detects measured interferometric pattern data associated with each of the multiple cores when the fiber sensor is wrapped onto the calibration fixture.

Abstract: An optical fiber with one or more microgratings is disclosed. Methods and apparatus are described for making an optical fiber with one or more microgratings. Methods and apparatus are described for an optical fiber with one or more microgratings Optical sensing methods and an optical sensing system effectively decouple strain range from the laser tuning range, permit the use of a smaller tuning range without sacrificing strain range, and compensate for ambiguity in phase measurements normally associated with smaller tuning ranges.

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: The ends of sensing and interrogating multicore fibers are brought into proximity for connection in a first orientation with one or more cores in the sensing fiber being paired up with corresponding one or more cores in the interrogating fiber. Optical interferometry is used to interrogate at least one core pair and to determine a first reflection value that represents a degree of alignment for the core pair in the first orientation. The relative position is adjusted between the ends of the fibers to a second orientation. Interferometry is used to interrogate the core pair and determine a second reflection value that represents a degree of alignment for the core pair in the second orientation. The first reflection value is compared with the second reflection value, and an aligned orientation is identified for connecting the sensing and interrogating fibers based on the comparison.

Abstract: In a multicore optical fiber sensor, an absorptive material integrated into the cladding, or into a waveguide core not used for sensing, may facilitate sensing. The absorptive material is absorptive to light in a wavelength band in which the fiber sensor is configured to operate. Coating such a fiber sensor with a material whose refractive index is smaller than that of the cladding may be done with reduced signal mixing.

Abstract: A tunable laser system includes a tunable laser to be scanned over a range of frequencies and an interferometer having a plurality of interferometer outputs. At least two interferometer outputs of the plurality of interferometer outputs have a phase difference. A wavelength reference has a spectral feature within the range of frequencies, and the spectral feature does not change in an expected operating environment of the tunable laser. Processing circuitry uses the spectral feature and the plurality of interferometer outputs to produce an absolute measurement of a wavelength of the tunable laser and controls the tunable laser based on a comparison of the absolute measurement of the wavelength of the tunable laser with a setpoint wavelength.

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 multiple optical cores configured in the fiber including a set of primary cores and an auxiliary core. An interferometric measurement system uses measurements from the multiple primary cores to predict a response from the auxiliary core. The predicted auxiliary core response is compared with the actual auxiliary core response to determine if they differ by more than a predetermined amount, in which case the measurements from the multiple primary cores may be deemed unreliable.

Abstract: Example embodiments add an optical amplifier to an multi-channel, continuously swept OFDR measurement system, adjust amplified swept laser output power between rising and falling laser sweeps, and/or utilize portions of a laser sweep in which OFDR measurements are not typically performed to enhance the integrity of the OFDR measurement system, improve the performance and quality of OFDR measurements, and perform additional measurements and tests.