Abstract: Disclosed herein is an optical fiber having an optically uniform coating having no physical defects in the coating greater than 100 micrometers in size over a length of 50 meters or greater.

Abstract: An arrangement and method that compensates for variation in grating strength associated with forming multiple gratings in multicore fiber is proposed where the writing efficiency of the beam(s) used to form the gratings is controlled to compensate for fiber lensing effects. In one case, a spacing between the multicore optical fiber and the beam source is controlled such that the writing efficiency (which decreases as a function of the space between the source and the fiber) compensates (at least in part) for the increased beam intensity attributed to the lensing effect of the fiber itself. The width of beam itself may also be controlled to modify the writing efficiency.

Abstract: A high backscattering fiber comprising a perturbed segment in which the perturbed segment reflects a relative power that is more than three (3) decibels (dB) above Rayleigh scattering. The high backscattering fiber also exhibits a coupling loss of less than 0.5 dB.

Abstract: A high backscattering fiber comprising a perturbed segment in which the perturbed segment reflects a relative power that is more than three (3) decibels (dB) above Rayleigh scattering. The high backscattering fiber also exhibits a coupling loss of less than 0.5 dB.

Abstract: A high backscattering fiber comprising a perturbed segment in which the perturbed segment reflects a relative power that is more than three (3) decibels (dB) above Rayleigh scattering. The high backscattering fiber also exhibits a coupling loss of less than 0.5 dB.

Abstract: A method of, and apparatus for, inscribing a grating in an optical waveguide so as to reduce transverse inscription variations, are provided. The waveguide is exposed to multiple beams or interference patterns of actinic radiation from multiple azimuthal directions. The beams of actinic radiation are preferably split into a plurality of beams that have wave vectors with different longitudinal components, e.g., via gratings such as phase masks. The periods and phases of the interference patterns of the beams of actinic radiation are preferably matched. A control beam may be provided that does not hit the waveguide. A control loop optionally controls at least one of the position or orientation of at least one of the beams of actinic radiation. The gratings are, for example, Bragg gratings.

Abstract: The disclosed embodiments provide systems and methods for mitigating lensing and scattering as an optical fiber is being inscribed with a grating. The disclosed systems and methods mitigate the lensing phenomenon by surrounding an optical fiber with an index-matching material that is held in a vessel with an integrated interferometer (e.g., phase mask, etc.). The index-matching material has a refractive index that is sufficient to reduce intensity variations of the actinic radiation within the optical fiber. Some embodiments of the system include different vessels for holding the index-matching material, with the vessel having an interferometer integrated into the vessel. These vessels permit the optical fiber to be surrounded by the index-matching material while the gratings are written to the optical fiber.

Abstract: Methods and systems using one or more distributed feedback (DFB) lasers for capturing changes in the lasing environment are disclosed. Specifically, a sensor for measuring a measurand, such as pressure or temperature, or changes in a measurand, includes a fiber with at least one core, at least one fiber laser cavity formed by a single fiber grating in the core, wherein the laser operates on at least two modes along at least part of its length. The DFB laser includes a section that is bent into a non-linear shape and at least one pump laser connected to the fiber laser cavity. When the DFB laser experiences a perturbation or measurand change that changes the spacing of the modes, a change in an RF beat note is generated. This beat note can then be measured and related to the measurand change.

Abstract: The disclosed embodiments provide systems and methods for mitigating lensing and scattering as an optical fiber is being inscribed with a grating. The disclosed systems and methods mitigate the lensing phenomenon by surrounding an optical fiber with an index-matching material that is held in a vessel with a sealed phase mask. The sealed phase mask allows it to be in contact with a liquid index-matching material without having the liquid index-matching material seep into the grooves of the sealed phase mask. Thus, for some embodiments, the sealed phase mask may be immersed in a liquid index-matching material without adversely affecting the function of the phase mask.

Abstract: A method and system for measuring chromatic dispersion, experienced by ASK/PSK modulated optical signals, are provided. Dispersion measurement is enabled either by encoding an additional overhead at lower baud rate or by monitoring signal SOP or RF spectrum of signal SOP. The bulk chromatic dispersion of the link is measured by analyzing the dispersion broadening of the overhead constellation or signal temporal diagram, or time-overlapped signal diagram, or overhead spectrum. This information is used to reduce the computation time required for electronic recovery of a highly dispersed signal.

Abstract: An optical fiber having at least one fiduciary mark is provided. The at least one fiduciary mark is located at one or more axial positions along the optical fiber. The at least one fiduciary mark is configured to produce at least one change in a backscattering signal in the optical fiber. The at least one change in a backscattering signal may be an abrupt change in the backscattering signal. The abrupt change in the backscattering signal occurs over a length of the optical fiber that is of the order of or less than a spatial resolution of an interrogation system employed to detect the backscattering signal.

Abstract: A high backscattering fiber comprising a perturbed segment in which the perturbed segment reflects a relative power that is more than three (3) decibels (dB) above Rayleigh scattering. The high backscattering fiber also exhibits a coupling loss of less than 0.5 dB.

Abstract: An optical fiber having at least one fiduciary mark is provided. The at least one fiduciary mark is located at one or more axial positions along the optical fiber. The at least one fiduciary mark is configured to produce at least one change in a Rayleigh backscattering signal in the optical fiber. The at least one change in a Rayleigh backscattering signal may be an abrupt change in the Rayleigh backscattering signal. The abrupt change in the Rayleigh backscattering signal occurs over a length of the optical fiber that is of the order of or less than a spatial resolution of an interrogation system employed to detect the Rayleigh backscattering signal.

Abstract: A method of designing multicore optical fibers is provided. A geometry for the core arrangement is selected. At least one of i) core width, ii) core position with respect to other cores, or iii) orientation with respect to incoming, outgoing, or at least partially traversing radiation such as an inscription beam are optimized. A design space is created in which no core shadows or blocks any other core with respect to incoming, outgoing, or at least partially traversing radiation. Optimization generally includes tracing tangents of core widths against an orthogonal axis and ensuring no overlap of space between said tangents on said axis. For twisted fiber, optimization also includes optimizing effective length and twist rate of the fiber. Devices entailing such fibers, such as multicore pump coupler and multicore fiber distributed feedback laser, are also contemplated.

Abstract: The disclosed embodiments provide systems and methods for mitigating lensing and scattering as an optical fiber is being inscribed with a grating. The disclosed systems and methods mitigate the lensing phenomenon by surrounding an optical fiber with a liquid index-matching material that is held in a vessel. The disclosed systems also include a replenishment mechanism that replenishes the liquid index-matching material as the optical fiber is pulled through the vessel.

Abstract: One measurement system comprises a polarimeter with a polarimeter detector bandwidth that partially overlaps with a signal bandwidth or completely overlaps with a signal bandwidth. The polarimeter measures a state of polarization (SOP) or a degree of polarization (DOP) of the signal in the presence of noise. The system further comprises a sampler that receives polarimeter signals from the polarimeter and samples those received signals at a specified sampling rate. The sampler outputs sampled data to a processor that calculates a mean DOP for the samples. Subsequently, the OSNR is determined from the calculated mean DOP.

Abstract: The present disclosure provides systems and methods for avoiding beam obstructions during inscription of fiber gratings. For some embodiments, an optical fiber is re-oriented during fiber inscription to avoid obstruction of the actinic beam.

Abstract: The disclosed embodiments provide systems and methods for mitigating lensing and scattering as an optical fiber is being inscribed with a grating. The disclosed systems and methods mitigate the lensing phenomenon by surrounding an optical fiber with an index-matching material that is held in a vessel with an integrated interferometer (e.g., phase mask, etc.). The index-matching material has a refractive index that is sufficient to reduce intensity variations of the actinic radiation within the optical fiber. Some embodiments of the system include different vessels for holding the index-matching material, with the vessel having an interferometer integrated into the vessel. These vessels permit the optical fiber to be surrounded by the index-matching material while the gratings are written to the optical fiber.

Abstract: A Raman distributed feedback (DFB) fiber laser is disclosed. It includes a pump source and a Raman gain fiber of a length smaller than 20 cm containing a distributed feedback (DFB) grating with a discrete phase structure located within no more than 10% off the center of the grating and wherein the Raman DFB fiber laser generates a laser signal with an optical spectrum, which has an optical bandwidth at half maximum optical intensity of less than 1 gigahertz (GHz) (wherein a maximum intensity frequency is different from the frequency of the pump laser). The Raman laser includes compensation for the nonlinear phase change due to Kerr effect and thermal effect resulting from absorption of the optical field, thus enhancing the conversion efficiency.

Abstract: A technique is described for terminating an optical fiber with low backreflection. At a selected end of the optical fiber segment, an endface is formed at a selected angle relative to the fiber axis. A suitable material is deposited onto the angled endface to form an angled reflective surface. The angled reflective surface is configured such that light propagating along the waveguide to the selected end of the optical fiber segment is reflected back into the optical fiber segment at an angle that prevents coupling of the reflected light into the fiber core. The reflected light is dissipated along the length of the fiber segment.