A polarization-related characteristic of an optical path is determined from a predetermined function of the mean-square of a plurality of differences between polarization-analyzed optical power parameters corresponding to pairs of wavelengths mutually spaced about a midpoint wavelength by a small optical frequency difference. At least some of the said differences correspond to wavelength pairs measured under conditions where at least one of midpoint wavelength, input state of polarization (I-SOP) or analyzed state of polarization (A-SOP) of a pair is different.

Using pump-probe measurements on multi-span optical links may result in the determination of one or more of the following: 1) wavelength-dependent power profile and gain evolution along the optical link; 2) wavelength-dependent dispersion map; and 3) location of regions of high polarization-dependent loss (PDL) and polarization-mode dispersion (PMD). Such measurements may be a useful diagnostic for maintenance and upgrade activities on deployed cables as well as for commissioning new cables.

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.

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 system for measuring a polarization extinction ratio (PER) using a reference master test jumper (MTJ) is disclosed. The system may include an optical source to transmit an optical signal via an optical fiber. The system may also include a device under test (DUT) communicatively coupled to the optical source via the optical fiber to receive the optical signal from the optical source. The system may also include an optical measurement component communicatively coupled to the device under test (DUT). In some examples, the optical fiber may be configured or initialized to be a reference master test jumper (MTJ) that minimizes inherent polarization extinction ratio (PER) of the optical fiber when measuring a polarization extinction ratio (PER) during a measurement action.

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.

An optical characteristic evaluation method evaluates unevenness of an optical characteristic in an optical film based on analysis of a polarized state of light transmitting through an optical film and an analyzer. The method includes the following, measuring a phase difference and an orientation angle in a plurality of positions; and quantifying and evaluating the unevenness of the optical characteristic based on a parameter of a vector of output light calculated by a formula 1 using a vector showing a polarized state of input light and a matrix showing a polarizing characteristic of the optical film and the analyzer. The formula 1 is as follows, formula 1: F2=MF1, F1: Stokes vector or Jones vector of input light, F2: Stokes vector or Jones vector of output light, M: Mueller matrix or Jones matrix of the optical film as the evaluation target and the analyzer.

A system for measuring a polarization extinction ratio (PER) using a reference master test jumper (MTJ) is disclosed. The system may include an optical source to transmit an optical signal via an optical fiber. The system may also include a device under test (DUT) communicatively coupled to the optical source via the optical fiber to receive the optical signal from the optical source. The system may also include an optical measurement component communicatively coupled to the device under test (DUT). In some examples, the optical fiber may be configured or initialized to be a reference master test jumper (MTJ) that minimizes inherent polarization extinction ratio (PER) of the optical fiber when measuring a polarization extinction ratio (PER) during a measurement action.

A monitorable hollow core (HC) optical fiber comprises one or more hollow core anti-resonant fiber (HC-ARF) segments and one or more monitoring segments alternatingly connected with the HC-ARF segments, and where each monitoring segment comprises one or more non-HC-ARF constituents. A method for monitoring a monitorable HC optical fiber comprises transmitting one or more first optical signals on the monitorable HC optical fiber, detecting one or more second optical signals on the monitorable HC optical fiber, and monitoring one or more optical properties of the monitorable HC optical fiber using the first optical signals and the second optical signals, where the monitoring is enabled as a result of interactions between the first optical signals and the non-HC-ARF constituents of the monitoring segments.

A monitorable hollow core (HC) optical fiber comprises one or more hollow core anti-resonant fiber (HC-ARF) segments and one or more monitoring segments alternatingly connected with the HC-ARF segments, and where each monitoring segment comprises one or more non-HC-ARF constituents. A method for monitoring a monitorable HC optical fiber comprises transmitting one or more first optical signals on the monitorable HC optical fiber, detecting one or more second optical signals on the monitorable HC optical fiber, and monitoring one or more optical properties of the monitorable HC optical fiber using the first optical signals and the second optical signals, where the monitoring is enabled as a result of interactions between the first optical signals and the non-HC-ARF constituents of the monitoring segments.