77 results about "Rayleigh backscattering" patented technology

Method and system are disclosed for de-embedding optical component characteristics from optical device measurements. In particular, the invention uses frequency domain averaging of the RBS on both sides of an optical component to determine one or more of its optical characteristics. Where the RBS has a slope (e.g., as in the case of a lossy fiber), a frequency domain least square fit can be used to determine the optical component characteristics. In addition, the invention uses a reference DUT to correct for variations in the frequency response of the photoreceiver. A reference interferometer is used in the invention to correct for sweep non-linearity of the TLS. The optical component characteristics are then de-embedded from optical device measurements to provide a more precise analysis of the optical device.

A preferred apparatus and method is presented in which a distributed fiber optic sensor is used in order to detect a disturbance along its length. A pulse of polarized light is launched into an optical fiber; as the pulse propagates along the optical fiber, it continuously loses a small portion of its energy due to Rayleigh backscatter. The Rayleigh backscattered light is analyzed using a polarization sensitive element such as a fiber polarizer. The dynamics of the time dependence of the polarization analyzed backscattered light is used to ascertain if there has been a disturbance along the length of the optical fiber. This technique can be used for applications in areas such as fiber optic telecommunications, perimeter security, fire detection, and pipelines.

A telecommunications multimode optical fiber is secured against intrusion by detecting manipulation of the optical fiber prior to an intrusion event. Pulses are injected using a launch arrangement which generates a narrow spectral width, under-filled, non-uniform mode field power distribution in the multimode optical fiber and Fresnel reflections and Rayleigh backscattering from the pulse are detected at the transmit end to monitor the modal power distribution in the fiber which changes on manipulation of the fiber. The Rayleigh backscattering time sliced data can be stored in a register until an intrusion event is detected. The detection is carried out by a modal power distribution detection system which includes an optical coupler to tap off a portion of the light which contains the higher order signal modes.

A telecommunications optical fiber is secured against intrusion by detecting manipulation of the optical fiber prior to an intrusion event. This can be used in a non-locating system where the detection end is opposite the transmit end or in a locating system which uses Fresnel reflections and Rayleigh backscattering to the transmit end to detect and then locate the motion. The Rayleigh backscattering time sliced data can be stored in a register until an intrusion event is detected. The detection is carried out by a polarization detection system which includes an optical splitter which is manufactured in simplified form for economic construction. This uses a non-calibrated splitter and less than all four of the Stokes parameters. It can use a polarimeter type function limited to linear and circular polarization or two linear polarizers at 90 degrees.

Reduced Rayleigh backscattering effect enables a longer-reach optical access communication network-thus it eliminates significant costs. Furthermore, a wavelength to an intelligent subscriber subsystem can be dynamically varied for bandwidth on-Demand and service on-Demand. A software module renders intelligence (and context awareness) to a subscriber subsystem and an appliance. An object can sense / measure / collect / aggregate / compare / map and connect / couple / interact (via one or more or all electrical / optical / radio / electro-magnetic / sensor / bio-sensor communication network(s) within and / or to and / or from an object) with another object, an intelligent subscriber subsystem and an intelligent appliance utilizing an Internet protocol version 6 (IPv6) and its subsequent versions.A construction of a near-field communication (NFC) enabled intelligent micro-subsystem and / or intelligent appliance with key applications (e.g., an intelligent, location based and personalized social network and an intelligent, location based and personalized direct and peer-to-peer marketing) are also described.

A telecommunications optical fiber is secured against intrusion by detecting manipulation of the optical fiber prior to an intrusion event. This can be used in a non-locating system where the detection end is opposite the transmit end or in a locating system which uses Fresnel reflections and Rayleigh backscattering to the transmit end to detect and then locate the motion. The Rayleigh backscattering time sliced data can be stored in a register until an intrusion event is detected. The detection is carried out by a polarization detection system which includes an optical splitter which is manufactured in simplified form for economic construction. This uses a non-calibrated splitter and less than all four of the Stokes parameters. It can use a polarimeter type function limited to linear and circular polarization or two linear polarizers at 90 degrees.

The present invention discloses an OPGW ice coating monitoring system and method based on a phase sensitive type optical time domain reflection system. A phase sensitive type optical time domain reflection system is used, to obtain distribution of a rayleigh backscattering signal in an overhead earth wire composite optical fiber cable in time and space; Fourier transformation is performed on a rayleigh backscattering signal phase demodulating result, and useless high frequency information is removed through low-pass filtering; a magnitude of a peak value frequency of the first resonance peak on each distance column is obtained according to frequency spectrum information; peak value frequencies of all distance column resonance peaks are spliced into a one-dimensional array and median filtering is performed; probability statistics is performed after long-time measurement, a frequency of a statistics result highest peak is recorded as a resonance frequency of a corresponding position, a confidence interval and a non-confidence interval are obtained according to a resonance frequency variance; a nominal resonance frequency and an actual resonance frequency are obtained through multipletimes of measurement, and an actual ice coating thickness is calculated according to the nominal resonance frequency and the actual resonance frequency calculation, so as to implement a distributed and intelligentized ice coating thickness monitoring method.

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.

An illustrative distributed acoustic sensing system includes a multi-mode optical fiber cable for distributed sensing and a distributed acoustic sensing interrogator coupled to the multi-mode optical fiber cable via a single mode optical fiber. The interrogator derives distributed acoustic measurements from Rayleigh backscattering light that is initiated with a substantially under-filled launch configuration that is designed to excite only the lowest-order modes of the multi-mode optical fiber. Mode conversion within the multi-mode optical fiber is anticipated to be negligible. For elastic scattering (i.e., Rayleigh scattering), it is further anticipated that the scattered light will be primarily returned in the incident propagation mode, thereby escaping the extraordinarily large coupling loss that would otherwise be expected from coupling a single-mode optical fiber to a multi-mode optical fiber for distributed sensing. Experiments with graded index multi-mode optical fiber have yielded positive results.