Nippon Telegraph and Telephone Corporation

Ntt Corporation

Shingo Ono

Hiroyuki Oshida

Tetsuya Manabe

Kunihiro Toge

Daisuke Iida

Yoshifumi Wakisaka

Chihiro Kito

The present disclosure relates to a device, including: a first light source for outputting incident light to a measured optical fiber or optical device; a second light source for outputting local light for being multiplexed with transmitted light through the measured optical fiber or optical device; and a signal processing unit for performing digital signal processing on a light-receiving signal I(t) obtained by multiplexing the transmitted light and the local light, wherein the signal processing unit is configured to calculate an autocorrelation function between the light-receiving signal I(t) and a signal I(t+τ) obtained by shifting the light-receiving signal by a time τ, and to measure a delay time difference between propagation modes in the measured optical fiber or optical device, from a peak position of the autocorrelation function.

Apparatus and method for measuring the delay time difference between propagation modes

An object of the present invention is to provide an optical access network that has high reliability for supporting information communication services and efficiently responds to difficult-to-predict optical fiber demand. An optical access network configuration according to the present invention includes an optical fiber cablethat is looped to connect a wiring sectionand an exchange officetogether (hereinafter, an upper loop), an optical fiber cablethat is looped and laid in each wiring section(hereinafter, a lower loop), and an optical fiber switching function unitinstalled at a connection pointbetween the upper loopand the lower loop. The optical fiber switching function unitis a wiring board or an optical switch which can be switched by connector connection. The wiring board or the optical switch may be remotely controllable.

Optical access network

Provided is an optical spectrum line width calculation method, apparatus, and program capable of calculating a spectrum line width of a laser to be measured from an optical interference signal generated by an optical interferometer having a delay line, based on a phase of the optical interference signal having a delay time longer than a delay time due to the delay line. The optical spectrum line width measurement apparatus includes a Mach-Zehnder interferometer, an optical receiver that receives an optical interference signal emitted from the Mach-Zehnder interferometer, an A/D converter that converts an analog electric signal output from the optical receiver into a digital electric signal, and a processing apparatus that processes the digital electric signal. Two light beams having a delay difference &#x3c4; are generated from light emitted from the laser to be measured, and an optical interference signal is generated by multiplexing the two light beams.

Optical spectral line width calculation method, device, and program

A distributed optical fiber vibration measurement device includes a phase constant difference computation unit causing the first backscattered light generated at the points of a plurality of optical fibers under test that are integrated to interfere with another light to obtain two AC components and determining a phase constant difference from the two AC components, a phase distribution data creation unit comparing amplitudes between the two AC components obtained by causing the first backscattered light generated at the points of the optical fibers under test to interfere with the other light and selecting, for each of the points, phase data regarding one of the two AC components having a larger amplitude to create phase distribution data with the phase data, and a vibration measurement unit identifying an optical path length difference between any two points of the optical fiber under test to measure vibration of the optical fiber under test.

Growing community of inventors

Musashino, Japan

Shingo Ono