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.

An elongate multi-core optical fiber instrument for insertion within a patient body includes a set of first optical fiber cores extending along a first sensing region of the multi-core optical fiber instrument, where each first optical fiber core includes a set of first sensors disposed along the first region and a set of second optical fiber cores extending along a second sensing region of the multi-core optical fiber instrument, where each second optical fiber core includes a set of second sensors disposed along the second sensing region. The first sensing region is located distal the second sensing region, and the first optical fiber cores extend along the second sensing region. Also disclosed is a console for providing an incident light signal to the multi-core optical fiber instrument, receiving reflected light signals from the sensors, and determining a parameter experienced by instrument in accordance with the reflected light signals.

The high sensitivity provided by an enhanced DAS system comprising a DAS interrogator and a high reflectivity fiber allows for the deployment of such a high reflectivity fiber as part of a wireline intervention cable which can be temporarily lowered into a well, thus avoiding the need to permanently cement such a high reflectivity optical fiber cable into the well. Instead, such a wireline cable incorporating the high reflectivity optical fiber has been found to be sensitive enough to detect micro-seismic activity and low frequency strain with many more measurement points and channels than conventional wireline deployed geophones and tiltmeters. Additionally, the cable requires no clamping and can be easily and quickly removed from one well and placed in another well.

Disclosed herein is a system, apparatus and method directed to detecting malposition of a medical device within a vessel of a patient, such as an Azygos vein. The medical device can include a multi-core optical fiber including a plurality of core fibers, where each of the plurality of core fibers includes a plurality of sensors is configured to reflect a light signal based on received incident light, and change a characteristic of the reflected light signal for use in determining a physical state of the multi-core optical fiber. The system can include a console having non-transitory computer-readable medium storing logic that, when executed, causes operations of providing a broadband incident light signal to the multi-core optical fiber, receiving reflected light signals, processing the reflected light signals, and determining whether the medical device has entered the Azygos vein of the patient based on the reflected light signals.

An optical waveguide device that enables single-mode coupling between cores to be coupled by controlling optical signal intensity variation due to an MPI. The optical waveguide device includes a first device end surface, a second device end surface, a waveguide, and a cladding layer. The waveguide has a first waveguide end surface and a second waveguide end surface, and light beams of a plurality of modes having different orders are guided. Further, the waveguide has one or more bent portions. The cladding layer has a refractive index lower than a refractive index of the waveguide. The waveguide has a waveguide length L of 5×10.sup.6 [nm] or more and 100×10.sup.6 [nm] or less, and has a structure in which an inter-mode group delay time difference Δβ1 satisfies a condition given by |Δβ1|≤½×10.sup.−12 [s]/L.

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.

The present invention relates to an optical shape sensing system, comprising an optical fiber sensor comprising an optical fiber having embedded therein a number of at least four fiber cores (1 to 6) arranged spaced apart from a longitudinal center axis (0) of the optical fiber, the fiber cores each having a resonance wavelength in response to light introduced into the fiber cores (1 to 6) in an unstrained state thereof. The system further comprises an optical interrogation unit (21) configured to interrogate the fiber cores (1 to 6) with light in a scan wavelength range including the resonance wavelengths of the fiber cores in an unstrained state of the fiber cores (1 to 6). The scan wavelength range is set such that a center wavelength of the scan wavelength range is decentered with respect to the resonance wavelength of at least one of the fiber cores (1 to 6).

This application relates to a fibre optic cable structure suitable for use as a sensing fibre optic for distributed acoustic sensing and having an improved sensitivity to transverse pressure waves. The application describes a fibre optic cable (300) having a longitudinal cable axis and comprising at least one optical fibre (301). The cable also comprises a compliant core material (303) mechanically coupled to the optical fibre(s), possible via a buffer (302) such that a longitudinal force acting on the compliant core material induces a longitudinal strain in the optical fibre(s). At least one deformable strain transformer (304) is coupled to the compliant core material and configured such that a force acting on the strain transformer in a direction transverse to the cable axis results in a deformation of the strain transformer thereby applying a longitudinal force to the compliant core material.

The present invention relates to an optical fiber sensor for shape sensing, comprising an optical fiber having embedded therein a number of at least four fiber cores (1 to 6) arranged at a distance from a longitudinal center axis (0) of the optical fiber, the number of fiber cores (1 to 6) including a first subset of at least two fiber cores (1, 3, 5) and a second subset of at least two fiber cores (2, 4, 6), the fiber cores (2, 4, 6) of the second subset being arranged to provide a redundancy in a shape sensing measurement of the fiber sensor (12′). The fiber cores (1, 3, 5) of the first subset are distributed in azimuthal direction around the center axis (0) with respect to one another, and each fiber core (2) of the second subset is arranged in non-equidistantly fashion in azimuthal direction around the center axis (0) with respect to two neighboring fiber cores (1, 3) of the first subset.

The present invention provides a plastic optical fiber comprising a core and a sheath consisting of at least one layer, the plastic optical fiber having a transmission loss of 120 dB/km or less as measured by a 25 m-1 m cutback method under conditions of a wavelength of 525 nm and an excitation of NA=0.45, and satisfying either one of the following conditions when a thickness of the innermost sheath layer is 0.5 μm to 4.5 μm, an amount of foreign matter having a size of 2 μm or greater contained in the innermost sheath layer is 2000/cm.sup.3 or less, or a size X (μm) of foreign matter contained in the innermost sheath layer and an amount Y of the foreign matter (number/cm.sup.3) satisfy formula (1) below: Y≦1200 X e.sup.(−0.067×X) (1). Such optical fibers have a low transmission loss of green light (in particular, light having a wavelength of 525 nm), enabling longer distance communication.