Nec Corporation

Nec Laboratories America, Inc.

Sumitomo Osaka Cement Co., Ltd.

Other

Takaaki Ogata

Yoshihisa Inada

Fatih Yaman

Shaoliang Zhang

Ting Wang

Yasuhiro Aoki

Takanori Inoue

Lei Xu

Junichiro Ichikawa

Kohei Nakamura

Kaoru Higuma

Eduardo Rodriguez

Hirotoshi Nagata

Yasuhisa Taneda

Ryu Yokoyama

Yukio Michishita

Hussam Batshon

Eduardo Mateo Rodriquez

Shinsuke Fujisawa

Junqiang Nochur Hu

Ezra Ip

Takashi Nakamura

Shuntaro Yamazaki

Yoshiro Sato

Kenichi Yoneyama

Tadashi Koga

Kenichi Nomura

Hitoshi Oguri

Junichiro Minowa

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

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

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

An optical communication substrate includes a plurality of cores to communicate optical signals; a rectangular input delivering a pump laser, and a shaped portion to combine the optical signals and the pump laser into a ring geometry at an output.

3D waveguide for efficient coupling of multimode pump and signals to a multicore fiber amplifier

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.

Fiber nonlinearity mitigation using strong mode coupling and large modal delay

Methods and systems for communication with an optimized constellation include coding an input data stream to a symbol stream according to an optimized constellation that has a non-Gray bit mapping and that has neighboring points having more than one bit difference farther apart than neighboring points having one bit difference. The symbol stream is modulated onto a transmission signal and subsequently demodulated at a receiver to produce a received symbol stream. The received symbol stream is decoded to a bitstream according to an optimized constellation that has a non-Gray bit mapping and that has neighboring points having more than one bit difference farther apart than neighboring points having one bit difference.

Constellation designs with non-gray bit mapping

A wavelength division multiplexing system and method featuring a wavelength monitor that is configured to receive a portion of a combined signal of wavelength division multiplexing channels and determine the wavelengths of each channel or the guardband between each channel in the combined signal. The wavelength monitor determines if there is excess laser drift for each channel in the combined signal. If excess laser drift is determined, feedback is sent to the transmitter for the signal with excess laser drift and the signal is adjusted to produce a target wavelength. The wavelength monitor may utilize optical intradyning in order to monitor the wavelengths of each channel in the combined signal.

Wavelength division multiplexing system and method including wavelength monitoring

At a receiver side, to enhance the performance of concatenated LDPC and TCM coding, an iterative decoding between TCM decoder and LDPC decoder enables improvement in the reliability of received LLRs of each symbol after each iteration. A SOVA output of the TCM is used for LDPC decoding, and then the updated LLRs from LDPC decoder are further looped back to the TCM decoder for the next iteration. In such a manner, the decoding performance could be significantly improved after just several iterations.

Iterative decoding for cascaded LDPC and TCM coding

A method includes evaluating an optical signal spectrum for estimated filtering parameters of an optical spectral filtering device for shaping optical signal spectrum, determining a feedback for fine tuning the optical spectral filtering device for nonlinearity tolerance enhancement in the optical transmission system, responsive to received optical signal quality in the optical signal spectrum; and using the feedback to adjust said optical spectral filtering device for predetermined shaping and predetermined fiber nonlinearity tolerance in the optical transmission system.

Optical spectral shaping for nonlinearity enhancement in high speed digital coherent optical transmissions

The invention is directed to a novel computer implemented method for finding a modulation format that has better receiver sensitivity than modulation formats that are currently being used, with a correlated symbol modulation in which neighboring symbols are coded and decoded together to increase receiver sensitivity.

Pair-wise symbol correlated high receiver sensitivity modulation format

Methods and systems for transmission and reception of ternary phase-shift keyed data that include mapping triplets of binary bits to pairs of ternary symbols, such that three bits of data are encoded across two symbols having three-point constellations; modulating the pairs of ternary symbols onto a carrier; and transmitting the modulated carrier across a transmission medium.

Polarization-switched differential ternary phase-shift keying

Methods, structures and systems for generating different polarization multiplexed signals wherein the drivers of the modulators are generic while a software-controlled manager allows the carrying of any standard 10 G/40 G/100 G data while&#x2014;at the same time&#x2014;being adaptively adjustable according to specific link requirements and users' requests in both dispersion-managed and uncompensated links.

Generation of polarization-alternated QPSK format

A method implemented in a transmission apparatus used in an optical fiber communications system for a polarization switched differential quaternary phase-shift keying (DQPSK) signal is disclosed. The method comprises splitting data into two or more data streams, inputting said two or more data streams to 1-bit DQPSK precoders to perform 1-bit DQPSK precoding, and multiplexing inphase outputs of the 1-bit DQPSK precoders to generate a first output; and multiplexing quadrature outputs of the 1-bit DQPSK precoders to generate a second output. Other methods, apparatuses, and systems also are disclosed.

Polarization switching for optical fiber communications

An inventive method for multi-symbol polarization switching for differential detection optical systems includes modulating a laser source by a DQPSK modulator, driving the DQPSK modulator with a data block configured for generating multi-symbol polarization-switched DQPSK differential-encoded signals, and polarizing the multi-symbol polarization-switched DQPSK signals with a polarizing modulator whose modulation speed is based on how often polarization states vary, wherein the data block provides a bits manipulation to provide the multi-symbol polarization switching thereby enabling differential detection for recovering correct original data by a receiver.

Multiple-symbol polarization switching for differential-detection modulation formats

A method for optical chirp-free optical polarization modulation includes dividing a data modulated optical signal into a first optical path and a second optical path, using a Mach-Zehnder intensity modulator in the first optical path for imparting a &#x3c0; phase difference between adjacent symbols of the data modulated optical signal in the first optical path, adjusting a delay and amplitude of symbols of the data modulated optical signal in the second path so that the symbols in the first path and the symbols in the second path are synchronized and have substantially equal power levels, and combining the first and second optical paths so that symbols from the first and second optical paths are in orthogonal polarizations.

Growing community of inventors

Tokyo, Japan

Takaaki Ogata