公开(公告)号：US20250158721A1

公开(公告)日：2025-05-15

申请号：US18834073

申请日：2022-02-10

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Masanori NAKAMURA ,  Takayuki KOBAYASHI ,  Fukutaro HAMAOKA ,  Yutaka MIYAMOTO

IPC: H04B10/61 ,  H04J14/06

Abstract: A signal processing method includes performing first equalization processing for converting a real component and an imaginary component of each polarization of a polarization multiplexed reception signal into a frequency domain signal, receiving, as input signals, a frequency domain signal of the real component and a frequency domain signal of the imaginary component of each polarization, and a signal obtained by performing frequency inversion on the frequency domain signal of the real component and the frequency domain signal of the imaginary component of each polarization and performing complex conjugate, performing, for each polarization, multiplying the real component and the imaginary component of each polarization by a complex transfer function, adding results, and performing inverse transform from the frequency domain signal to a time domain signal, performing second equalization processing for performing frequency inversion of the real component of each polarization included in the input signal, performing frequency inversion of a real component signal and an imaginary component subjected to complex conjugate, multiplying the imaginary component signals subjected to complex conjugation by a complex transfer function, adding results of the multiplications, and performing inverse transform from a frequency domain signal to a time domain signal, and adding or subtracting a transmission data bias correction signal to or from a signal obtained by adding a first addition signal to a second addition signal.

公开(公告)号：US20240250768A1

公开(公告)日：2024-07-25

申请号：US18289380

申请日：2021-05-21

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Shimpei SHIMIZU ,  Takushi KAZAMA ,  Takayuki KOBAYASHI ,  Yutaka MIYAMOTO ,  Takeshi UMEKI

IPC: H04J14/02

CPC classification number: H04J14/0209 ,  H04J14/02216

Abstract: The present invention provides an optical amplification system (1) having a plurality of cascade-connected optical amplification units (11), wherein the optical amplification units (11) comprise: a band division unit (111) that divides an optical signal into optical signals of two different bands; a polarized wave division unit (112) that divides the divided optical signals into two polarized wave components orthogonal to each other, an excitation light multiplexing unit (113) that multiplexes excitation light and the optical signals divided by the polarized wave division unit (112); an amplification medium (115) that generates an optical parametric amplification and amplifies the optical signals; an excitation light division unit (117) that divides the excitation light and the optical signals amplified by the amplification medium (115); a polarized wave synthesis unit (118) that synthesizes the two divided polarized wave components; and a band multiplexing unit (119) that multiplexes the two divided bands.

公开(公告)号：US20240248369A1

公开(公告)日：2024-07-25

申请号：US18289389

申请日：2021-05-20

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Shimpei SHIMIZU ,  Takushi KAZAMA ,  Takayuki KOBAYASHI ,  Yutaka MIYAMOTO ,  Takeshi UMEKI

IPC: G02F1/39 ,  G02F1/35 ,  H04B10/079 ,  H04B10/294 ,  H04B10/61

CPC classification number: G02F1/392 ,  G02F1/3546 ,  H04B10/07955 ,  H04B10/2942 ,  H04B10/6166

Abstract: An optical amplification device includes: a polarization demultiplexing unit that separates an optical signal into a first polarized wave and a second polarized wave; a first optical amplification unit that amplifies the first polarized wave by using a first amplification medium; a second optical amplification unit that amplifies the second polarized wave by using a second amplification medium; a first band demultiplexing unit that demultiplexes the first polarized wave into a band component of the first polarized wave and a band component of first phase conjugate light; a second band demultiplexing unit that demultiplexes the second polarized wave into a band component of the second polarized wave and a band component of second phase conjugate light; a signal monitoring unit that measures a first optical power value of either the band component of the first polarized wave or the band component of the first phase conjugate light and a second optical power value of either the band component of the second polarized wave or the band component of the second phase conjugate light; an amplification gain control unit that controls an amplification band and gain of the first amplification medium and an amplification band and gain of the second amplification medium on the basis of the first optical power value and the second optical power value; and a polarization combination unit that multiplexes the band component of the first polarized wave and the band component of the second polarized wave not measured by the signal monitoring unit.

公开(公告)号：US20230261755A1

公开(公告)日：2023-08-17

申请号：US18012032

申请日：2020-07-08

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Hiroto KAWAKAMI ,  Hiroshi YAMAZAKI ,  Yutaka MIYAMOTO

IPC: H04B10/54 ,  H04B10/50

CPC classification number: H04B10/541 ,  H04B10/501

Abstract: An optical transmitter includes an I-component optical modulation unit, a Q-component optical modulation unit, and a 2×2 optical coupler. The I-component optical modulation unit generates modulated light based on an I-component data signal. The Q-component optical modulation unit generates modulated light based on a Q-component data signal. The 2×2 optical coupler receives the modulated light generated by the I-component optical modulation unit from a first input port, receives the modulated light generated by the Q-component optical modulation unit from a second input port, generates two optical QAM signals having a phase conjugate relationship from the modulated light which has been input from the first input port and the modulated light which has been input from the second input port, outputs one of said two optical QAM signals from a first output port, and outputs the other one of said two optical QAM signals from a second output port.

公开(公告)号：US20220407600A1

公开(公告)日：2022-12-22

申请号：US17777569

申请日：2019-11-28

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Shimpei SHIMIZU ,  Takayuki KOBAYASHI ,  Masanori NAKAMURA ,  Yutaka MIYAMOTO

IPC: H04B10/2513 ,  H04B10/079

Abstract: A computation unit uses an assumed chromatic dispersion amount to compensate for dispersion of a coherently received optical signal and performs arithmetic of a signal power of the optical signal that is dispersion compensated. The computation unit performs computation of an evaluation function when a signal power and a delayed signal power obtained by applying a predetermined delay to the signal power satisfy a threshold condition. The evaluation function is a function for evaluating whether the assumed chromatic dispersion amount is a chromatic dispersion amount of the optical signal using the difference between the signal power and the delayed signal power. The chromatic dispersion amount calculation unit calculates a chromatic dispersion amount of the optical signal based on the computation result of the evaluation function by the computation unit when each of a plurality of different assumed chromatic dispersion amounts is used.

公开(公告)号：US20220399940A1

公开(公告)日：2022-12-15

申请号：US17777545

申请日：2019-11-28

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Shimpei SHIMIZU ,  Takayuki KOBAYASHI ,  Yutaka MIYAMOTO

IPC: H04B10/2507 ,  H04B10/61

Abstract: An optical transmission system includes: a transmission unit configured to co-propagate a signal light in which data is modulated and an idler light having complex amplitude that is phase conjugate with the signal light via an optical transmission medium; at least one optical amplifier configured to perform a phase sensitive amplification operation through an action among the signal light, the idler light, and an excitation light in a nonlinear medium; and a reception unit configured to receive the signal light that has been amplified by the optical amplifier, coherently detect the signal light and the idler light individually, and conduct a diversity synthesis to demodulate the data.

公开(公告)号：US20220329343A1

公开(公告)日：2022-10-13

申请号：US17638830

申请日：2019-09-06

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Koki SHIBAHARA ,  Takayuki MIZUNO ,  Yutaka MIYAMOTO

IPC: H04J14/04 ,  H04B10/60

Abstract: An optical signal processing apparatus of an embodiment is an optical signal processing apparatus for separating and detecting an optical signal transmitted in a mode division multiplexing optical communication method by signal processing based on a multi-input multi-output (MIMO)-type linear filter. The device includes a signal processing unit configured to estimate weighting factors of the MIMO-type linear filter by sequential calculation based on an affine projection method. In the sequential calculation of the signal processing device, an output signal by the sequential calculation is expressed by a correlation vector indicating a correlation between the plurality of input signals, a smoothing prefilter vector indicating, of smoothing prefilter factors indicating a relationship between the weighting factors at current time and input signals from a first time being a past predetermined time to the current time, smoothing prefilter factors corresponding to each time from the first time to a second time that corresponds to an affine projection order in the affine projection method, and input signals from the first time to the second time.

公开(公告)号：US20210376924A1

公开(公告)日：2021-12-02

申请号：US17263733

申请日：2019-08-15

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Akira ISODA ,  Takayuki MIZUNO ,  Koki SHIBAHARA ,  Takayuki KOBAYASHI ,  Yutaka MIYAMOTO

IPC: H04B10/077 ,  H04J14/06 ,  H04B10/25

Abstract: A crosstalk estimation system includes: a light source unit that generates a polarization-multiplexed light, which is a polarized light having multiplexed polarizations, of each wavelength in a sideband of a modulated signal and emits the polarization-multiplexed light of each wavelength; a multiplexer that multiplexes the modulated signal with the polarization-multiplexed light for each core, which is associated with one of the wavelengths; a transmission line that transmits the modulated signal multiplexed with the polarization-multiplexed light of each wavelength through a different core; a separation unit that separates the polarization-multiplexed light from the modulated signal multiplexed with the polarization-multiplexed light for each core; a measurement unit that generates light intensity data on the polarization-multiplexed light of each wavelength; and an estimation unit that estimates a crosstalk between the cores based on a difference in light intensity between the polarization-multiplexed light of the wavelengths.

公开(公告)号：US20210013985A1

公开(公告)日：2021-01-14

申请号：US16971856

申请日：2019-02-20

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Koki SHIBAHARA ,  Takayuki MIZUNO ,  Yutaka MIYAMOTO

IPC: H04J14/04 ,  H04B10/2581 ,  H04Q11/00

Abstract: An optical transmission system includes a plurality of transmission paths that transmit a mode multiplexing signal, and one or more mode permutation units provided between the transmission paths. The mode permutation unit performs mode permutation to interchange modes to be used between at least some optical signals among respective optical signals of a plurality of types of modes that are multiplexed to the mode multiplexing signal input from the transmission path on an input side, and outputs the mode multiplexing signal subjected to the mode permutation to the transmission path on an output side.

公开(公告)号：US20180375607A1

公开(公告)日：2018-12-27

申请号：US15775265

申请日：2017-01-11

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Kohki SHIBAHARA ,  Takayuki MIZUNO ,  Hiroto KAWAKAMI ,  Yutaka MIYAMOTO

IPC: H04J14/04 ,  H04B7/0413 ,  H04L25/03 ,  H04B10/50 ,  H04B10/69

Abstract: An optical transmission system includes an optical transmission apparatus and an optical reception apparatus. The optical transmission apparatus includes a conversion unit that converts multiple binary data sequences into data in a predetermined signal format; a coding unit that generates multiple pieces of coded data by performing predetermined coding on each of the multiple pieces of converted data; an optical signal generation unit that generates multiple optical signals by converting the multiple pieces of coded data into optical signals; and a mode multiplexer that converts the multiple optical signals into different modes, generates a mode-division multiplexed optical signal by mode-division multiplexing the optical signals, and transmits the generated mode-division multiplexed optical signal to the optical reception apparatus. The optical reception apparatus includes a mode demultiplexer that demultiplexes the mode-division multiplexed optical signal transmitted from the optical transmission apparatus into light in different modes; a photoelectric conversion unit that converts the light in the multiple different modes into electrical signals; an analog/digital conversion unit that converts the multiple electrical signals into coded data; and an MIMO equalization processing unit that performs MIMO equalization processing on the converted coded data.