A time domain reflectometry measurement apparatus and method is provided. Measurement data of a time domain reflectometry measurement are analyzed with respect to previously acquired empirical measurement data of error-free or faulty devices with known failures. In this way, failures can be identified in the device under test without the need of opening the device.

In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. :A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

Aspects of the present disclosure describe distributed fiber optic sensing (DFOS) systems, methods, and structures that advantageously overcome problems encountered when operating DFOS systems over operational telecommunications facilities namely, cross-phase modulation, and uneven amplitude profiles through the use of a novel constant amplitude coded DFOS employing suppressed out-of-band signaling.

An optical pulse test apparatus according to the present disclosure includes a light generation unit configured to generate an optical pulse for generating backscattered light beams in an optical fiber under test and generate first light having an optical frequency for amplifying backscattered light in an LP11 mode out of the backscattered light beams in two LP modes through stimulated Brillouin scattering, and second light having an optical frequency for attenuating backscattered light in an LP01 mode out of the backscattered light beams in the two LP modes through stimulated Brillouin scattering, a mode demultiplexing unit configured to input the optical pulse, the first light, and the second light generated by the light generation unit into the optical fiber under test in the LP01 mode and separate, out of the backscattered light beams generated by the optical pulse, the backscattered light in the LP11 mode, a local oscillation light generation unit configured to generate local oscillation light by which the backscattered light separated by the mode demultiplexing unit is heterodyne-detected, a light reception unit configured to multiplex the backscattered light in the LP11 mode separated by the mode demultiplexing unit and the local oscillation light generated by the local oscillation light generation unit and photoelectrically convert the multiplexed light into an electrical signal, and an arithmetic processing unit configured to calculate a time-intensity distribution of the electrical signal obtained by the light reception unit photoelectrically converting the backscattered light in the LP11 mode.

Aspects of the subject disclosure may include, for example, determining distinct timing offsets between an input port and output ports of a multiport optical device. An optical signal is injected at an input port of the device to obtain output signals at the output ports, which are injected into downstream fibers. An optical multipath return signal is received via the input port of the device, including a combination of measured events including reflections, backscatter, or both. A number of similar events expected in the number of downstream optical fibers is calculated to obtain an expected multipath signature based on configuration data. Results of the optical multipath return signal are then compared to the expected multipath signature to obtain comparison results. One of the measured events is distinguished from the others based on the first comparison results and the distinct timing offsets. Other embodiments are disclosed.

A processing device disposed inside a transmitter/receiver intended for use in optical fiber sensing using an optical fiber in order to enable restricting utilization of a prescribed range of acquired data, the processing device comprising: a mask unit which masks a prescribed range of acquired data, which is the data acquired by the transmitter/receiver through the optical fiber sensing; and an output unit which outputs post-masking data, which is the data that has undergone the aforementioned masking, to the outside of the transmitter/receiver, wherein the acquired data prior having the masking performed thereon for the prescribed range is not outputted to the outside.

Methods of measuring an anomaly, any induced change in physical parameters such as strain, temperature, and so forth, in an optical fiber. One method may include launching a plurality of probe pulses from a probe source; recording a Brillouin scattering spectrum from a plurality of reflection signals generated in the optical fiber, responsive to the plurality of probe pulses; determining a relative motion between the optical fiber and the anomaly during the recording the Brillouin back-scattering spectrum; and dynamically adjusting the Brillouin back-scattering spectrum according to the relative motion, or performing an adjustment of the Brillouin back-scattering spectrum after acquisition of the Brillouin back-scattering spectrum.

In some examples, an optical time-domain reflectometer (OTDR) device may include a laser source to emit a plurality of laser beams. Each laser beam may include a different pulse width. A control unit may analyze, for each laser beam, a backscattered signal from a device under test (DUT). The control unit may generate, for each backscattered signal, a trace along the DUT. Further, the control unit may generate, based on an analysis of each trace along the DUT, a combined trace that identifies optical events detected along the DUT.

Aspects of the present disclosure describe monitoring of optical fiber by distributed temperature sensing (DTS) and determining optical fiber degradation and/or abnormal environmental events including landslides, fires, etc., from DTS data.

There are provided methods and systems that enable the use of the backscattering pattern produced by an optical fiber in an OTDR trace as a signature (also referred to herein as the “RBS fingerprint”) to recognize an optical fiber. It was found that it may be difficult to obtain repeatable signatures as those are sensitive to the wavelength of the OTDR laser source and the temperature of the fiber. OTDR methods and systems that are adapted to compare the backscattering pattern in a more repeatable manner are therefore provided. Once the repeatability issue is overcome, such signature can be used for identification purposes and enable new applications.