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.

A method and system for determining deformation in a cable 110, wherein a sensing optical fiber arrangement is applied along the cable 110. The method comprises injecting a forward pulse pump signal in the optical fiber in a forward direction of the optical fiber; injecting a reverse probe signal in the optical fiber in a reverse direction of the optical fiber; measuring a stimulated Brillouin backscattering; and based on the Brillouin backscattering measurement, providing information 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, and advantageously, 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. The method and system may be used during deployment of a subsea power cable 110 to a sea bottom 100 from a cable reel 130 positioned on the deck of a cable-laying vessel 120 floating on a sea surface 140.

According to examples, a fiber-optic testing source for testing a multi-fiber cable may include a laser source communicatively coupled to a plurality of optical fibers connected to a connector. The fiber-optic testing source may include at least one photodiode communicatively coupled to at least one of the plurality of optical fibers by at least one corresponding splitter to implement a communication channel between the fiber-optic testing source and a fiber-optic testing receiver. The communication channel may be operable independently from a polarity associated with the multi-fiber cable. The fiber-optic testing receiver may include a plurality of photodiodes communicatively coupled to a plurality of optical fibers. The fiber-optic testing receiver may include at least one laser source communicatively coupled to at least one of the plurality of optical fibers by at least one corresponding splitter to implement the communication channel between the fiber-optic testing receiver and a fiber-optic testing source.

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 method of testing an optical network with a device, the method comprising transmitting a light pulse in a first direction from a light source of the device through the optical network toward an optical reflector, wherein the light pulse travels through the optical network in the first direction, is reflected by the reflector, and travels though the optical network in a second direction opposite the first direction after being reflected by the reflector; measuring a power level of the light pulse after the light pulse travels through the optical network in the second direction; determining a total loss of the light pulse in both the first direction and the second direction; and determining a loss of the optical network by subtracting a loss of the light pulse in the second direction only from the determined total loss of the light pulse.

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.

Aspects of the present disclosure describe systems, methods and structures providing bipolar cyclic coding for Brillouin optical time domain analysis that may be employed—for example—to determine high accuracy temperature and/or strain measurements along an optical fiber. Systems, methods, and structures according to the present disclosure employ the bipolar cyclic coding technique that advantageously overcomes the problems that plague the prior art and provides extended sensing range resulting from superior signal-to-noise characteristics.

According to examples, a fiber-optic testing source for testing a multi-fiber cable may include a laser source communicatively coupled to a plurality of optical fibers connected to a connector. The fiber-optic testing source may include at least one photodiode communicatively coupled to at least one of the plurality of optical fibers by at least one corresponding splitter to implement a communication channel between the fiber-optic testing source and a fiber-optic testing receiver. The communication channel may be operable independently from a polarity associated with the multi-fiber cable. The fiber-optic testing receiver may include a plurality of photodiodes communicatively coupled to a plurality of optical fibers. The fiber-optic testing receiver may include at least one laser source communicatively coupled to at least one of the plurality of optical fibers by at least one corresponding splitter to implement the communication channel between the fiber-optic testing receiver and a fiber-optic testing source.

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.

Systems and methods for characterizing an optical fiber performed in part by an optical node (12) in an optical line system (10) include performing one or more measurements to characterize the optical fiber (16, 18) with one or more components (50, 52) at the optical node (12), wherein the one or more components (50, 52) perform functions during operation of the optical node (12) and are reconfigured to perform the one or measurements independent of the functions; and configuring the optical node (12) for communication over the optical fiber (16, 18) based on the one or more measurements. The one or more components can include any of an Optical Service Channel (OSC), an Optical Time Domain Reflectometer (OTDR), and an optical amplifier. The configuring can include setting a launch power into the optical fiber based on the one or more measurements.