Nec Corporation

Nec C Orporation

Eduardo Rodriguez

Yoshihisa Inada

Fatih Yaman

Takanori Inoue

Kohei Nakamura

Shaoliang Zhang

Hussam Batshon

Takaaki Ogata

Shinsuke Fujisawa

Ryuji Aida

Yue-Kai Huang

Ting Wang

Ezra Ip

Yoshinari Takigawa

Satoshi Mikami

Takehiro Nakano

Ryu Kurahashi

Weiyang Mo

Hassam Batshon

Takigawa Yoshinari

Aspects of the present disclosure describe systems, methods. and structures in which guided acoustic Brillouin (GAWBS) noise is measured using a homodyne measurement technique and demonstrated using a number of optical fibers, such fibers being commonly used in contemporary optical communications systems. The measurements are made with single spans and determined to be consistent with separate multi-span long-distance measurements. Additionally, a technique for preparing an optical fiber exhibiting superior GAWBS noise characteristics by reducing coherence length of the optical fiber by spinning the fiber at a high rate during the drawing process such that birefringence coherence length is reduced.

Optical fiber exhibiting low guided acoustic Brillouin scattering (GAWBS) noise and measurement thereof

Earthquake detection via fiber sensing is provided using using a supervisory path of submarine cables wherein the supervisory system/path of a submarine optical cable conveys portion(s) of an optical signal back to an origin location periodically—i.e., at every repeater location. Advantageously, since it is known where a returning signal is coming from, a resolution equivalent to an undersea span length may be determined—which is sufficient for wide area disturbances such as earthquakes. The returned signal is sufficiently strong such that the signal-to-noise ratio of a returned/received signal is not limited by the ASE noise of the amplifiers. The returned signal is much larger as compared to a normal distributed acoustic sensing (DAS) return signal since the return signal according to aspects of the present disclosure is directed backward via an optical coupler/reflector/circulator having a much larger coupling ratio as compared to normal Rayleigh back scattering utilized in DAS.

Fiber sensing using supervisory path of submarine cables

Aspects of the present disclosure are directed to systems, methods, and structures providing for the accurate measurement of guided acoustic-wave Brillouin scattering in optical fiber transmission systems and facilities.

Accurate measurement for guided acoustic-wave Brillouin scattering

The object is to provide an optical repeater, a manufacturing method of an optical repeater, and a relay method of an optical signal that can achieve a redundant configuration for a failure of a light source outputting an excitation light with a simple configuration. Light sources output lights. The optical amplification units amplify optical signals using excitation lights. An optical distribution unit branches the lights output from the light sources into two branched lights and distributes the branched lights in such a manner that each of the optical amplification units receives the branched light branched from the lights from two different light sources as the excitation light.

Optical repeater, manufacturing method of optical repeater, and relay method of optical signal

Aspects of the present disclosure describe estimating/measuring core-cladding concentricity error in optical fibers. In sharp contrast to the prior art, our inventive method is based on measuring a seemingly unrelated property of fibers called guided acoustic wave Brillouin scattering (GAWBS). As we shall show and describe, by analyzing this GAWBS property we advantageously determine what level of CCCE is exhibited by the optical fiber.

Estimating core-cladding concentricity error in optical fibers using guided acoustic-wave Brillouin scattering

Aspects of the present disclosure describe systems, methods. and structures directed to an integrated 3-way branching unit switch module suitable for undersea application.

Integrated 3-way branching unit switch module having small footprint

Aspects of the present disclosure describe methods for reducing guided acoustic wave Brillouin (GAWBS) noise in an optical fiber that may be included in an optical communications system by reducing the polarization diffusion length of the fiber by increasing the birefringence of the optical fiber, the increased birefringence of the optical fiber being increased with respect to its average magnitude. Additionally, the polarization diffusion length is reduced by reducing the coherence length of birefringence of the optical fiber.

Method for reducing GAWBS noise by reducing polarization diffusion length

Aspects of the present disclosure describe a three-way branching unit switch module having a small footprint suitable for application in an undersea application.

Three-way branching unit switch module having small footprint

Aspects of the present disclosure describe a method for estimating mode field distribution in optical fibers from guided acoustic-wave Brillouin scattering wherein light for which the optical mode-field distribution is determined remains in the optical fibers and the distribution is made for light inside the fiber, and not at a fiber/air interface or other perturbation points to the fiber resulting in a more accurate representation of the optical mode-field distribution in the fiber. Since light is always in the fiber during the determination, no complicated fiber preparation steps or procedures are required and the mode-field distribution is determined as an average distribution along the length of the fiber under test.

Estimating mode field distribution in optical fibers from guided acoustic wave brillouin scattering

Aspects of the present disclosure describe a method for digital coherent transmission systems that advantageously provides low-complexity, single-step nonlinearity compensation based on artificial intelligence (AI) implemented in a deep neuron network (DNN).

Single-step nonlinearity compensation using artificial intelligence for digital coherent transmission systems

Aspects of the present disclosure describe systems, methods, and structures that advantageously amplify optical signals through the effect of optical pump signals generated by a multicore laser diode and multicore rare-earth doped optical fiber in optical communication with a 3D waveguide structure and a multicore input signal fiber providing a plurality of optical signals for amplification.

Multicore fiber amplifier with high power efficiency

Aspects of the present disclosure describe systems, methods and structures including high-density submarine/undersea reconfigurable optical add/drop multiplexers (ROADM) having remote wavelength selective switch (WSS) redundancy.

High-density submarine ROADM unit with remote WSS redundancy

Aspects of the present disclosure describe systems, methods and structures for optical fiber nonlinearity compensation using neural networks that advantageously employ machine learning (ML) algorithms for nonlinearity compensation (NLC) that advantageously provide a system-agnostic model independent of link parameters, and yet still achieve a similar or better performance at a lower complexity as compared with prior-art methods. Systems, methods, and structures according to aspects of the present disclosure include a data-driven model using the neural network (NN) to predict received signal nonlinearity without prior knowledge of the link parameters. Operationally, the NN is provided with intra-channel cross-phase modulation (IXPM) and intra-channel four-wave mixing (IFWM) triplets that advantageously provide a more direct pathway to underlying nonlinear interactions.

Optical fiber nonlinearity compensation using neural networks

Systems and methods for transmission filtering are provided. A receiver includes an input coupled to a transmission line to receive distorted optical symbols. A distortion filter is coupled to the input to replace the distorted optical symbols with predicted symbols using a trained neural network. A decoder is coupled to the distortion filter to decode the predicted symbols.

Transmission filtering using machine learning

Aspects of the present disclosure describe fiber nonlinearity induced transmission penalties are reduced both in fibers with large polarization-mode dispersion, and in coupled-core multicore fibers (CC-MCF). In the case of coupled multi-core fibers, the requirement for modal delay is less.

Growing community of inventors

Tokyo, Japan

Eduardo Rodriguez