A method and system for determining deformation in a cable, where a sensing optical fiber arrangement is applied along the cable. The method includes injecting a forward pulse pump signal in the optical fiber in a forward direction of the optical fiber and injecting a reverse probe signal in the optical fiber in a reverse direction of the optical fiber. A stimulated Brillouin backscattering is measured and, based on the Brillouin backscattering measurement, information is provided about a deformation of the cable. The forward pulse pump signal is provided as a sum of a stationary signal component and an interrogation pulse component, the stationary signal component has an energy below a Brillouin activation level and the interrogation pulse signal component has an energy which results in that the sum of the stationary signal component and the interrogation pulse signal component exceeds the Brillouin activation level.

This disclosure describes inputting pulsated pump light in a fundamental mode or a first higher-order mode into one end of an optical fiber under test constructed by connecting two optical fibers in series; inputting probe light having an optical frequency difference within a Brillouin frequency shift range with respect to the pump light into the other end of the optical fiber under test in the fundamental mode or the first higher-order mode; measuring a Brillouin gain distribution related to a distance of transmitted light intensity of probe light output from the one end into which the pump light was input; and calculating each inter-modal coupling efficiency at the connection point of the optical fiber under test.

A testing device includes a test port, a light source, a measurement element, and a controller. A method of testing an optical system with the testing device includes, and/or the testing device is configured for, measuring an unloaded reference signal when the testing device is not connected to the optical system and storing the unloaded reference signal in a memory of the testing device. The method and/or configuration also includes detecting a signal from the optical system after storing the unloaded reference signal. Based on the detected signal, it is determined that the optical system is connected to a test port of the testing device. A test of the optical system with the testing device is automatically initiated in response to determining that the optical system is connected to the test port of the testing device.

A light intensity distribution measurement apparatus is presented that is capable of accurately measuring the intensity of light in each mode at each position of an optical fiber through which light is propagated in a plurality of modes. With the light intensity distribution measurement apparatus, a gain coefficient matrix is acquired in advance, which is constituted by Brillouin gain coefficients of propagation modes with predetermined optical frequency differences measured using a reference optical fiber that exhibits the same properties as a measurement-target optical fiber and that does not cause mode coupling, and the intensity distribution of light in each propagation mode in a lengthwise direction of the measurement-target optical fiber is calculated based on the gain coefficient matrix and a difference in light intensity before and after Brillouin amplification of the probe light emitted in a predetermined propagation mode at a predetermined optical frequency difference measured using the measurement-target optical fiber.

A duplex visual tester for testing multiple fiber optic cable runs includes a housing having a first LED and a second LED in a duplex fiber connection. The first LED and the second LED are in electronic communication with a power source, a battery, an on/off switch, and a timer configured to pulse the first LED and the second LED. The first LED and the second LED are installed in the duplex fiber connection. The first LED has a first color, and the second LED has a second, different color, wherein the first color and the second color have the same luminosity. Preferably, the timer pulses the first LED and the second LED at between eight and ten Hz, such that the first color and second color can be seen in the fiber optic cable run.

An object is to provide a light intensity distribution measurement method and a light intensity distribution measurement apparatus that are capable of accurately measuring the intensity of light in each mode at each position of an optical fiber through which light is propagated in a plurality of modes. With a light intensity distribution measurement apparatus according to the present invention, a gain coefficient matrix is acquired in advance, which is constituted by Brillouin gain coefficients of propagation modes with predetermined optical frequency differences measured using a reference optical fiber that exhibits the same properties as a measurement-target optical fiber and that does not cause mode coupling, and the intensity distribution of light in each propagation mode in a lengthwise direction of the measurement-target optical fiber is calculated based on the gain coefficient matrix and a difference in light intensity before and after Brillouin amplification of the probe light emitted in a predetermined propagation mode at a predetermined optical frequency difference measured using the measurement-target optical fiber.

An object is to provide a propagation property analyzing apparatus that can alleviate the influence of an error caused by crosstalk, and accurately evaluate a few-mode optical fiber that multiplexes a plurality of modes, in a distributional and non-destructive manner. Provided is a propagation property analyzing apparatus that analyzes propagation properties of a few-mode optical fiber that multiplexes a plurality of modes, which is an optical fiber under test, in a lengthwise direction thereof, through Brillouin time domain analysis, the propagation property analyzing apparatus including: means for inputting probe light in a desired mode from a distal end of the optical fiber under test; means for inputting a light pulse that is in the desired mode and that has a frequency difference equivalent to a Brillouin frequency shift in the desired mode, relative to the probe light, from a proximal end of the optical fiber under test, as pump light corresponding to the probe light; and means for inputting a light pulse that is in another mode different from the desired mode and that has a frequency difference equivalent to a Brillouin frequency shift in the other mode, relative to the probe light, as secondary probe light corresponding to the probe light, from the proximal end of the optical fiber under test.

In some examples, an optical time-domain reflectometer (OTDR) device may include a laser source to emit a laser beam into a device under test (DUT), and a connection port to connect the OTDR device to a first end of the DUT, where the OTDR device may be designated a first OTDR device. A sensor display generator may determine a length of the DUT, receive, from a second OTDR device connectable to a second opposite end of the DUT, and over the DUT, OTDR information acquired by the second OTDR device in a direction from the second OTDR device towards the first OTDR device, and ascertain, based on acquisition by the first OTDR device, further OTDR information in a direction from the first OTDR device towards the second OTDR device. The sensor display generator may generate a bi-directional combined schematic display that includes relevant optical events with respect to the DUT.

An optical fiber loss measurement device includes a unit configured to input pump light at a first frequency in a predetermined mode to a measurement target optical fiber in which a plurality of modes propagate from a first end, and input probe light at a second frequency to which a Brillouin frequency shift is applied to a second end, a Brillouin gain acquisition unit configured to measure an intensity of light output from the first end to acquire Brillouin gains in a longitudinal direction of the measurement target optical fiber using a BOTDA method, and a unit configured to measure a loss in the predetermined mode of the measurement target optical fiber, and the probe light is in a mode in which an electric field distribution in a cross section of the measurement target optical fiber is axisymmetric.

The present invention relates to a method and device for measuring optical nonlinearity of an optical fiber to be measured comprising a plurality of cores having mutually coupled waveguide modes. The method includes, at least, preparing a laser light source emitting laser light and a detecting unit determining an optical intensity, inputting laser light into a specific core of the optical fiber to be measured, determining the intensity of a specific wavelength component caused by optical nonlinearity among the reflective light components from the optical fiber to be measured, and determining optical nonlinearity of the optical fiber to be measured on the basis of the intensity of the specific wavelength component.