The present invention has an object to provide an optical fiber testing method and an optical fiber testing device capable of measuring the delay ratio between the modes at each position of a fiber over a long distance in which a plurality of modes propagate.

An optical fiber testing method and its device according to the present invention, measure the change amount for the wave number k of a Brillouin Frequency Shift ν in stimulated Brillouin scattering generated in the same acoustic mode, with respect to each target propagation mode. Thereby, the ratio of the change amount measured at each propagation mode is acquired as the group delay ratio between the modes.

Light output from a light source is distributed to intensity modulators that are associated with different spatial modes and that have different modulation conditions. An operation for receiving modulated light from each of the intensity modulators is performed for SDM fibers of different lengths while the light source is in operation, and pieces of optical power information are determined for respective spatial modes to be measured, from difference information regarding the lengths and the received optical powers.

An apparatus includes optical fiber ports into which optical fiber channels are input, the optical fiber channels carrying and outputting light, a mask configured to, while spinning at a frequency, allow a first portion of the light incident on the mask to pass through the mask, and block a remaining portion of the light incident on the mask, based on a pattern on the mask, and a photodetector configured to detect the allowed first portion of the light as input signals. The apparatus further includes a testing device configured to transform the input signals to a frequency domain, to obtain measured signals in frequencies respectively corresponding to the optical fiber channels, and determine whether each of the measured signals is a failure by comparing the obtained measured signals with a threshold signal.

An apparatus includes optical fiber ports into which optical fiber channels are input, the optical fiber channels carrying and outputting light, a mask configured to, while spinning at a frequency, allow a first portion of the light incident on the mask to pass through the mask, and block a remaining portion of the light incident on the mask, based on a pattern on the mask, and a photodetector configured to detect the allowed first portion of the light as input signals. The apparatus further includes a testing device configured to transform the input signals to a frequency domain, to obtain measured signals in frequencies respectively corresponding to the optical fiber channels, and determine whether each of the measured signals is a failure by comparing the obtained measured signals with a threshold signal.

The present disclosure relates to a polarity detector for detecting polarity of a patch cord, that is capable of sequentially inputting an optical signal into channels of a connector of the patch cord, receiving the optical signal being output, and thereby discerning the polarity of the patch cord quickly and precisely. Particularly, the present disclosure is characterized to spectrally output the optical signal from the light source as a plurality of unit optical signals, and to selectively block or pass the spectrally output plurality of unit optical signals, by heat, and thereby effectively inputting the optical signal into each channel of the connector.

The present disclosure relates to a polarity detector for detecting polarity of a patch cord, that is capable of sequentially inputting an optical signal into channels of a connector of the patch cord, receiving the optical signal being output, and thereby discerning the polarity of the patch cord quickly and precisely. Particularly, the present disclosure is characterized to spectrally output the optical signal from the light source as a plurality of unit optical signals, and to selectively block or pass the spectrally output plurality of unit optical signals, by heat, and thereby effectively inputting the optical signal into each channel of the connector.

An optical fiber distributed monitoring system and method is provided. The system includes a laser device, an acousto-optic modulator, a phase matching interferometer, a photoelectric detector and a phase demodulation module. After entering the phase matching interferometer, the Rayleigh backscattering light containing parameter information output from the sensing optical fiber enters the two arms of the phase matching interferometer respectively, and the light of the two arms of the phase matching interferometer is phase-modulated by the first modulation wave and the second modulation wave, respectively and then interfere with each other to generate interference light. The photoelectric detector converts a light signal into an electric signal, and the phase demodulation module processes the electric signal based on the Hilbert algorithm to obtain the parameter change of the environment under test.

An optical fiber distributed monitoring system and method is provided. The system includes a laser device, an acousto-optic modulator, a phase matching interferometer, a photoelectric detector and a phase demodulation module. After entering the phase matching interferometer, the Rayleigh backscattering light containing parameter information output from the sensing optical fiber enters the two arms of the phase matching interferometer respectively, and the light of the two arms of the phase matching interferometer is phase-modulated by the first modulation wave and the second modulation wave, respectively and then interfere with each other to generate interference light. The photoelectric detector converts a light signal into an electric signal, and the phase demodulation module processes the electric signal based on the Hilbert algorithm to obtain the parameter change of the environment under test.

Light output from a light source is distributed to intensity modulators that are associated with different spatial modes and that have different modulation conditions. An operation for receiving modulated light from each of the intensity modulators is performed for SDM fibers of different lengths while the light source is in operation, and pieces of optical power information are determined for respective spatial modes to be measured, from difference information regarding the lengths and the received optical powers.