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.

A system 1 for remote sensing of information to be transmitted, said system 1 comprising; an optical time-domain reflectometer, OTDR, 2 adapted to transmit an optical probe signal OPS into an optical fiber 3 and to measure a backscattered signal power; and at least one electro-optical signaling unit 4 connected to said optical fiber 3, wherein the electro-optical signaling unit 4 is configured to change an attenuation and/or a reflection of the optical probe signal OPS depending on at least one signal provided by one or more signal sources 5 in response to the information to be transmitted.

A composite connector for optical power meter is provided, which includes a fixation base and an active connection base. The fixation base is installed on an optical power meter; the fixation base includes a left hole, a right hole and a central hole. The active connection base includes a bottom plate, an active pin, a first fiber socket and a second fiber socket. The first fiber socket and the second fiber socket are disposed on the bottom plate. The active pin penetrates through the bottom plate and is inserted into the left hole, whereby a first circle, whose center is at the active pin and circumference passes through the first fiber socket as well as the second fiber socket, overlaps a second circle, whose center is at the left hole and circumference passes through the central hole, in the normal direction of the active connection base.

In some examples, fiber optic virtual sensing may include generating, by a virtual sensor generator that is operatively connected to a device under test (DUT), at least one virtual sensor along the DUT. A DUT interrogator may be operatively connected to the DUT to transmit a stimulus optical signal into the DUT. The DUT interrogator may analyze reflected light resulting from the transmitted stimulus optical signal. The DUT interrogator may determine, based on the analysis of the reflected light, an attribute of the DUT sensed by the at least one virtual sensor.

An optical test system capable of accurately measuring a loss of each mode at each position of an optical fiber which propagates a plurality of modes is provided. An optical fiber loss measuring apparatus for measuring using an OTDR technique includes a crosstalk suppressing light input unit that inputs light of a different mode different from the predetermined mode, the different mode causing crosstalk to the probe light, to the target optical fiber to be measured through the near end as crosstalk suppressing light at a second frequency obtained by giving a frequency that is equivalent to a Brillouin frequency shift of the predetermined mode to a first frequency, a light separating unit that removes light of the second frequency from light that is output from the target optical fiber to be measured through the near end to separate light of the first frequency, and a propagation mode loss measuring unit that measures an intensity of the separated light to measure a loss of each propagation mode at each position of the target optical fiber to be measured.

The present invention has an object to provide an optical fiber test method and an optical fiber test apparatus for measuring a mode dependent loss and an inter-modal crosstalk in a fundamental mode and a first higher-order mode at a connection point of a few-mode fiber. In the optical fiber test method and test apparatus according to the present invention, the mode dependent loss and the inter-modal crosstalk in the fundamental mode and the first higher-order mode at the connection point are calculated by using an approximation expression of an inter-modal coupling efficiency that is obtained in approximating electric field distributions of the fundamental mode and the first higher-order mode in a few-mode fiber by Gaussian function and Hermite Gaussian function.

A pulse testing method and device, a testing apparatus, and a storage medium are disclosed, the pulse testing method includes: performing a pulse test on an optical fiber by using a plurality of pulses of different pulse widths respectively to obtain test data; and fitting the test data corresponding to the plurality of pulses of different pulse widths.

An objective is to provide an acoustic mode propagation speed measurement method and an acoustic mode propagation speed measurement device capable of measuring a propagation speed of an acoustic mode without cutting or processing an optical fiber wire.

According to the present invention, an acoustic mode propagation speed measurement method includes: acquiring a frequency shift spectrum of Brillouin scattered light generated in an optical fiber; fitting the frequency shift spectrum using a Gauss function; acquiring a spectral full-width at half maximum w from a fitted curve using the Gauss function; and calculating a propagation speed V.sub.A of an acoustic mode of the optical fiber by substituting the acquired spectral full-width at half maximum w into a linear function of the spectral full-width at half maximum w and the propagation speed V.sub.A of the acoustic mode.

A method for suppressing coherent and polarization-induced fading by simultaneous monitoring of loss and vibration is provided. By using merely common single-mode sensing fibers, the polarization diversity-based measurement method solves the conflict between Φ-OTDR and COTDR in terms of polarization state. In addition, the method not only achieves a better coherent fading noise suppression effect but also enhances the capability of recognizing small loss events in the monitoring of loss parameters. Meanwhile, the method can suppress the influence of coherent fading on the phase demodulation of Φ-OTDR and reconstruct a vibration signal with high fidelity in the monitoring of perturbation parameters, which can effectively reduce the error rate of external perturbation warning.

Systems and methods include detecting a fast fiber transient on a span based on analyzing power data, wherein the power data is for any of optical wavelengths of traffic channels, optical service channel (OSC) wavelengths, and telemetry from a network element; and responsive to detecting the fast fiber transient, causing an optical time domain reflectometer (OTDR) trace on the span with a specific configuration based on the fast fiber transient.