Provided is a cladded single crystal sapphire optical fiber. In one embodiment, the innovation provides a method for forming a cladding in a single crystal sapphire optical fiber by reactor irradiation. The reactor irradiation creates ions external to the fiber that enter the fiber, displace atoms in the fiber, and are implanted in the fiber, thus modifying the index of refraction of the fiber near the surface of the fiber and creating a cladding in the sapphire fiber.

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.

An apparatus, including: an optical sensor fiber having a first end optically couplable to receive light from a light source, wherein the optical sensor fiber is a multimode optical fiber configured to carry light in different spatial propagating modes, wherein the optical sensor fiber is constructed such that environmental fluctuations couple light energy between some of the spatial propagating modes; a spatial propagating mode demultiplexer optically coupled to a second end the optical sensor fiber and configured to separate a plurality of light signals received from different ones of the spatial propagating modes; and an optical receiver configured to process the separated light signals and to estimate a longitudinal position of one of the environmental fluctuations along the optical sensor fiber based a measured delay between arrival times of the separated light signals.

A method and equipment based on multi-core fiber Bragg grating (FBG) probe for measuring structures of a micro part are provided. The provided method relates to how to accomplish measuring structures of a micro part by transforming two or three-dimensional contact displacements into spectrum shifts of the multi-core FBG probe, and to reconstruct the structure geometry of a micro part. The provided equipment can be used to bring the spherical tip of the multi-core FBG probe into contact with a micro part, to determine coordinates of contact points, and to reconstruct the structure geometry of a micro part. The provided method and equipment feature high sensitivity, low probing force, high inspecting aspect ratio and immunity to environment interference.

Systems, methods, and devices of the various embodiments enable mitigation of the effects of birefringence in Optical Frequency Domain Reflectometer (OFDR) sensing fiber. Various embodiments enable the measurement of the polarization state of the light in a sensing fiber throughout the entire sensing cable in a highly distributed manner typical of OFDR systems. Various embodiments enable the production of a distributed fiber birefringence measurement throughout the length of an OFDR sensing fiber. Various embodiments may enable OFDR to be 100% polarization diverse, meaning that polarization effects in the fiber optic cables and sensing fiber do not negatively effect measurements. Additionally, the highly distributed measurement of the polarization state and related birefringence in a sensing fiber of the various embodiments may enable new types of measurements such as pressure, twisting, and bending along the sensing fiber.

The disclosure relates in particular to a method for parameterizing a system for measuring an absolute position, the system including a permanent magnet, at least one probe that is mobile relative to the magnet over a given path, and a controller providing position information calculated on the basis of the arctangent of the ratio, wherein a correction coefficient G is assigned, between the output signals of the probe, wherein the signals are pseudo-sinusoidal and squared. The method includes an optimization operation that involves selecting the value of the coefficient G that minimizes the errors of the measurement system resulting from the pseudo-sinusoidal character of the signals output from the probe.

Methods and apparatus for interferometric seismic imaging and creation of a high-resolution three-dimensional seismic volume in proximity to a wellbore are described. In contrast to current methods that deliver positions of microseismic events using a small fraction of the microseismic wavefield, the present invention provides for the analysis of a full microseismic wavefield. In a preferred embodiment, the method includes creating a planar image slice and/or corridor between the location of one or more microseismic events and one or several sensor arrays to produce a multitude of azimuthally orientated planar image slices and/or corridors. The method further includes adding the planar image slice and/or corridor contributions to create a single three-dimensional volume for analysis and rendering.

According to some embodiments a fiber sensor comprises: an optical fiber configured for operation at a wavelength from about 300 nm to about 2000 nm, and further defined by a transmission end, a another end, a fiber outer diameter and a fiber length, the fiber comprising: (a) a hybrid core comprising a single mode core portion and a multi-mode core portion; and (b) a cladding surrounding the hybrid core.

The present invention relates to an optical fiber for an SPR sensor, characterized in that the optical fiber is comprised of a core layer and a cladding layer surrounding the core layer, and the cladding layer is doped with metal nanoparticles.

A system and method for discriminately measuring the response of a plurality of spatially separated fiber sensors positioned along an optical fiber using a sweep of electromagnetic radiation. Each fiber sensor affects the transmission of a particular wavelength of electromagnetic radiation and the particular wavelength affected by a given fiber sensor is dependent on at least one environmental property of the given fiber sensor. By detecting the particular wavelength affected by a given sensor, it is possible to determine the environmental property of the given sensor.