Aspects of the present disclosure describe systems, methods. and structures in which guided acoustic Brillouin (GAWBS) noise is measured using a homodyne measurement technique and demonstrated using a number of optical fibers, such fibers being commonly used in contemporary optical communications systems. The measurements are made with single spans and determined to be consistent with separate multi-span long-distance measurements. Additionally, a technique for preparing an optical fiber exhibiting superior GAWBS noise characteristics by reducing coherence length of the optical fiber by spinning the fiber at a high rate during the drawing process such that birefringence coherence length is reduced.

There are provided techniques for characterizing and testing a cable routing connection configuration connection arrangement comprising a plurality of optical fiber links connected between at least a first connection device at a first end and a second multi-fiber connection device at a second end. Test light is injected into one or more of the optical fiber links via corresponding optical fiber ports of the first connection device. At least one image of the second multi-fiber connection device is captured. Test light exiting the optical fiber link(s) through optical fiber port(s) of the second multi-fiber connection device is imaged as light spot(s) in the captured image. Positions on the second multi-fiber connection device that corresponds to the optical fiber port(s) are determined based on a pattern of the light spot(s) in the captured image. In some implementations, the provided techniques allow detection or verification of cable routing connection configurations at multi-fiber distribution panels.

There is provided a method for measuring the PDL of a DUT as a function of the optical frequency ν within a spectral range, which uses a single wavelength scan over which the input-SOP varies in a continuous manner. The power transmission through the DUT, curve T(ν), is measured during the scan and the PDL is derived from the sideband components of the power transmission curve T(ν) that results from the continuously varying input-SOP. More specifically, the Discrete Fourier Transform (DFT) of the power transmission curve T(ν) is calculated, wherein the DFT shows at least two sidebands. At least two sidebands are extracted and their inverse DFT calculated individually to obtain complex transmissions (ν), =−J . . . J, where J is the number of sidebands on one side. The response vector |m(ν) of the DUT is derived from the complex transmissions (ν) and a matrix determined by the continuous trajectory of the SOP of the input test lightwave; and the PDL of the DUT as a function of ν (PDL curve) is derived therefrom.

Aspects of the present disclosure describe a method for estimating mode field distribution in optical fibers from guided acoustic-wave Brillouin scattering wherein light for which the optical mode-field distribution is determined remains in the optical fibers and the distribution is made for light inside the fiber, and not at a fiber/air interface or other perturbation points to the fiber resulting in a more accurate representation of the optical mode-field distribution in the fiber. Since light is always in the fiber during the determination, no complicated fiber preparation steps or procedures are required and the mode-field distribution is determined as an average distribution along the length of the fiber under test.

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.

The present invention provides novel apparatus and methods for fast quantitative measurement of perturbation of optical fields transmitted, reflected and/or scattered along a length of an optical fibre. The present invention can be used for point sensors as well as distributed sensors or the combination of both. In particular this technique can be applied to distributed sensors while extending dramatically the speed and sensitivity to allow the detection of acoustic perturbations anywhere along a length of an optical fibre while achieving fine spatial resolution. The present invention offers unique advantages in a broad range of acoustic sensing and imaging applications. Typical uses are for monitoring oil and gas wells such as for distributed flow metering and/or imaging, seismic imaging, monitoring long cables and pipelines, imaging within large vessel as well as for security applications.

Aspects of the present disclosure describe a method for estimating mode field distribution in optical fibers from guided acoustic-wave Brillouin scattering wherein light for which the optical mode-field distribution is determined remains in the optical fibers and the distribution is made for light inside the fiber, and not at a fiber/air interface or other perturbation points to the fiber resulting in a more accurate representation of the optical mode-field distribution in the fiber. Since light is always in the fiber during the determination, no complicated fiber preparation steps or procedures are required and the mode-field distribution is determined as an average distribution along the length of the fiber under test.

A line monitoring system may include a laser source to launch a probe signal over a first bandwidth, a polarization maintaining tap to receive and split the probe signal, into a first portion and a second portion, a polarization rotator to receive the first portion and send the first portion to a transmission system, a return tap to receive the second portion and to receive a return signal from the transmission system, wherein the return signal being derived from the first portion, a photodetector coupled to receive an interference signal from the return tap, wherein the interference signal is generated by a mixing the return signal and the second portion, where the photodetector is arranged to output a power signal based upon the interference signal, and a power measurement system to measure the power signal at a given measurement frequency over a second bandwidth, comparable to the first bandwidth.

An OVNA system employing an array of reference delays to estimate distance-variant phase distortion in probe light during an optical-frequency sweep thereof. The estimated distance-variant phase distortion is then used to perform a phase correction for the digital electrical signals generated in response to the probe light being passed through a device under test (DUT) during the same optical-frequency sweep. Advantageously, the performed phase correction enables the OVNA system to provide a more-accurate determination of certain optical characteristics of the DUT than that achievable without such phase correction.

Optical fabrication monitor structures can be included in a design fabricated on a wafer from a mask or fabrication reticle. A first set of components can be formed in an initial fabrication cycle, where the first set includes functional components and monitor structures. A second set of components can be formed by subsequent fabrication processes that can potentially cause errors or damage to the first set of components. The monitor structures can be implemented during fabrication (e.g., in a cleanroom) to detect fabrication errors without pulling or scrapping the wafer.