In some examples, automatic OTDR-based testing may include determining, based on analysis of a signal that is received from a DUT that is to be monitored, whether the DUT is optically connected. Based on a determination that the DUT is optically connected, a measurement associated with the DUT may be performed.

In some examples, optical fiber identification and distance measurement may include utilizing a reflectometer and optical fiber connection device that includes a Rayleigh wavelength pass filter to pass, in one direction, an optical reflectometer signal to an optical fiber. The reflectometer and optical fiber connection device may include a Raman wavelength pass filter to filter out, in another direction, Rayleigh backscattering from the optical reflectometer signal. Further, the Raman wavelength pass filter may pass, in the another direction, a Raman Anti-Stokes signal from the optical fiber.

An optical fiber testing device (300) being plugged into a port at which optical signals including communication and test signals within different wavelength bands being received, comprises an optical connector (304) including a plug body surrounding a ferrule holding an optical fiber (301) and a reflector component (326) carried with the optical connector (304). The reflector component (326) is optically coupled to the rear of the optical fiber and reflects the test signal. A method for testing an optical fiber, comprises removably securing a reusable ruggedized optical fiber testing device to a ruggedized port of an optical fiber terminal to optically couple to an optical fiber under test, transmitting a test signal over the optical fiber under test, and using the reflector component to return the test signal over the optical fiber under test when receiving the test signal.

An optical time domain reflector structure and the optical assembly is disclosed in the present invention. The optical assembly comprise an optical time domain reflector structure, a light guiding module and an optical transceiver sub-module. By disposing the optical time domain reflector structure in the optical transceiver sub-module can reduce the overall space. The optical signals emitted from the light guiding module can be reflected back to the optical fiber by the disposing of the reflection filter of the optical time domain reflector structure. Due to the two different radius of curvature of the first reflection surface and the second reflection surface of the reflection filter, the required optical signal can be completely refocused to return to the optical fiber, so that the intensity loss of the optical signals can also be reduced.

A stage, electric probes, an optical probe, an electric measurement device, an optical measurement device, and a first positioning mechanism are provided. The stage includes a second positioning mechanism that changes relative positional relationship between the electric probes and an electric connection portion of each of the optical elements. The electric probes electrically connect the electric measurement device and each of the optical elements. The optical probe optically connects the optical measurement device and each of the optical elements. The first positioning mechanism changes relative positional relationship between the optical probe and an optical connection portion of each of the optical elements.

An object is to provide an optical pulse test method and an optical pulse test device with which it is possible to measure transmission losses of a basic mode and a first higher-order mode at a connection point at which two-mode optical fibers are connected in series, without switching the mode of input test light. An optical pulse test device according to the present invention inputs a test optical pulse in a basic mode (or a first higher-order mode) from one end of an optical fiber under test, the test optical pulse having such a wavelength that the test optical pulse can propagate in the basic mode and the first higher-order mode, measures intensity distributions of a basic mode component and a first higher-order mode component of return light of the test optical pulse relative to the distance from the one end, finds, from the intensity distributions, losses of the basic mode component and the first higher-order mode component of the return light at a desired connection point of the optical fiber under test, and calculates transmission losses of the basic mode and the first higher-order mode at the connection point based on expressions (8) (or expressions (9)).

Systems and methods include a method for overcoming optical time domain reflectometry (OTDR) dead zone limitations by using a few-mode fiber (FMF). Optical pulses are transmitted by a transmitter of an OTDR system through a mode MUX/DEMUX into an FMF. Light signals directed by the FMF in a backward direction through the mode MUX/DEMUX are received by the OTDR system through N single-mode fiber (SMF) ports corresponding to N modes in the FMF. Light signals from N−1 dead-zone-free SMF ports are collected by the OTDR system. Losses are measured and faults are located in the FMF based at least on the light signals.

An optical fiber sensor system and method for monitoring a condition of a linear structure such as a pipeline is provided which is capable of providing continuous monitoring in the event of a break in the sensing optical fiber or fibers. The system includes at least one sensing fiber provided along the length of the linear structure, and first and second interrogation and laser pumping sub-systems disposed at opposite ends of the sensing fiber, each of which includes a reflectometer. The reflectometer of the first interrogation and laser pumping sub-system is connected to one end of the sensing fiber. The reflectometer of the second interrogation and laser pumping sub-system is coupled to either (i) an end of a second sensing fiber provided along the length of the linear structure which is opposite from the one end of the first sensing fiber, or (ii) the opposite end of the first sensing fiber. Before any break of the sensing fiber or fibers occurs, each reflectometer redundantly monitors the condition of the linear structure over its entire length. After any such break occurs, each reflectometer will continue to receive signals up to the point of the break from opposite ends of the structure.

In some examples, fiber optic cable location may include transmitting a coherent laser pulse into a device under test (DUT). Based on an analysis of reflected light resulting from the transmitted coherent laser pulse, changes in intensity of the reflected light caused by a plurality of signals directed towards the DUT may be determined. Further, based on the changes in intensity of the reflected light, a location of the DUT may be determined.

A monitoring arrangement is described for use in monitoring the condition of an umbilical 12 extending between a first location and a second location, the monitoring arrangement comprising a first SSTDR monitoring unit 28 electrically connected to the umbilical 12 at the first location and monitoring the condition of a first part 12a of the umbilical 12, and a second SSTDR monitoring unit 30 electrically connected to the umbilical 12 at the second location and monitoring the condition of a second part 12b of the umbilical 12.