Patents by Inventor Kengo Horikoshi
Kengo Horikoshi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
-
Publication number: 20240007195Abstract: An adaptive equalizer includes an updating unit that updates a step size of a vector of a tap coefficient used for controlling an adaptive filter based on a time-series update vector in accordance with a time-series input and output of the adaptive filter that tracks a polarization state of an optical signal received by a coherent optical receiver. The updating unit updates the step size based on a DC gain of the update vector. The updating unit may update the step size for each update vector component based on a DC gain for each update vector component.Type: ApplicationFiled: December 14, 2020Publication date: January 4, 2024Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo HORIKOSHI, Seiji OKAMOTO, Masanori NAKAMURA
-
Publication number: 20230421420Abstract: An aspect of the present invention is an adaptive equalization filter for an optical transmission system, including: a main signal filter; and a coefficient computation unit that updates the filter coefficient of the main signal filter. The pre-stage filter and the post-stage filter receive a sample of the main signal as an input. The pre-stage coefficient computation unit obtains the filter coefficient of the pre-stage filter by feedback control using the gradient method. The post-stage coefficient computation unit obtains the filter coefficient of the post-stage filter by feedforward control. The convolution computation unit obtains the filter coefficient of the main signal filter by convolution computation of the filter coefficient of the pre-stage filter obtained by the pre-stage coefficient computation unit and the filter coefficient of the post-stage filter obtained by the post-stage coefficient computation unit.Type: ApplicationFiled: November 25, 2020Publication date: December 28, 2023Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Etsushi YAMAZAKI, Seiji OKAMOTO, Masanori NAKAMURA, Kengo HORIKOSHI, Takeo SASAI, Yoshiaki KISAKA
-
Patent number: 11799547Abstract: A signal processing apparatus includes: a coefficient update unit configured to approximate a characteristic of a transmission line of an optical signal by a first tap coefficient vector of which an L0 norm is a predetermined value or less; a zeroing unit configured to generate a second tap coefficient vector by replacing, with 0, a tap coefficient of which an absolute value is less than a threshold among tap coefficients of the first tap coefficient vector; and an adaptive filter configured to perform, based on the second tap coefficient vector, adaptive equalization processing on a digital signal corresponding to an optical signal received via the transmission line.Type: GrantFiled: September 17, 2019Date of Patent: October 24, 2023Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo Horikoshi, Masanori Nakamura, Seiji Okamoto, Hideki Nishizawa, Etsushi Yamazaki
-
Patent number: 11711151Abstract: An optical transmission system according to an embodiment includes: an optical transmission unit which modulates an optical signal into which a known signal is inserted and transmits the optical signal; and an optical reception unit which receives the optical signal from the optical transmission unit, wherein the optical reception unit includes: an optical receiver which performs coherent detection of a reception signal of the optical signal received from the optical transmission unit; a receiver transfer function estimation section which estimates a nonlinear response transfer function of the optical receiver based on the known signal included in the reception signal after the detection by the optical receiver; and a receiver compensation section which compensates nonlinear distortion of the reception signal after the detection based on the nonlinear response transfer function which the receiver transfer function estimation section estimates.Type: GrantFiled: May 23, 2019Date of Patent: July 25, 2023Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Asuka Matsushita, Masanori Nakamura, Kengo Horikoshi, Shoichiro Kuwahara, Yoshiaki Kisaka
-
Patent number: 11683093Abstract: An electric digital received signal obtained from a received optical signal is segmented into blocks of a certain length with an overlap of a length determined in advance with an adjacent block. Fourier transformation is performed for each of the blocks. The blocks subjected to the Fourier transformation are stored consecutively in time series, a coefficient determined based on a wavelength dispersion compensation amount according to one of frequency positions and a delay amount according to one of the frequency positions and one of time positions is applied to each of frequency component values included in a plurality of the stored blocks, and the blocks to which the coefficient has been applied and which are obtained by adding up the frequency component values to which the coefficient has been applied for each of the frequency positions are generated. Inverse Fourier transformation is performed on the generated blocks to which the coefficient has been applied.Type: GrantFiled: June 6, 2019Date of Patent: June 20, 2023Assignee: Nippon Telegraph and Telephone CorporationInventors: Masanori Nakamura, Seiji Okamoto, Kengo Horikoshi, Shuto Yamamoto, Takayuki Kobayashi, Yoshiaki Kisaka, Masahito Tomizawa
-
Publication number: 20230097741Abstract: An optical reception apparatus includes a wavelength dispersion compensation unit that performs wavelength dispersion compensation individually on reception signals that are obtained by receiving, by a coherent detecting scheme, an optical signal modulated in a subcarrier modulation scheme and by performing division on a subcarrier-by-subcarrier basis, and a plurality of delay compensation units that compensate for a delay between reception signals at different subcarriers among the reception signals at subcarriers obtained by the wavelength dispersion compensation.Type: ApplicationFiled: March 11, 2020Publication date: March 30, 2023Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo HORIKOSHI, Masanori NAKAMURA, Seiji OKAMOTO, Etsushi YAMAZAKI, Asuka MATSUSHITA, Takeo SASAI
-
Patent number: 11575443Abstract: An optical transmission system includes: a first optical transmitting unit for transmitting a first optical signal having a first wavelength; a second optical transmitting unit for transmitting a second optical signal having a second wavelength; an output adjustment unit for acquiring the first optical signal and the second optical signal, adjusting signal intensities of the acquired optical signals, and outputting the optical signals; a multiplexer for multiplexing the first optical signal and the second optical signal that have been subjected to signal intensity adjustment and outputting a multiplexed signal; an amplifier for amplifying the multiplexed signal; a first optical receiving unit for receiving the amplified first optical signal; and a second optical receiving unit for receiving the amplified second optical signal.Type: GrantFiled: January 30, 2020Date of Patent: February 7, 2023Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takashi Mitsui, Toshiaki Shitaba, Akihiro Tanabe, Kengo Horikoshi, Hisao Yoshinaga
-
Patent number: 11463169Abstract: A wavelength dispersion amount estimation apparatus includes a correlation signal generation unit configured to generate, from a receive signal, a first signal including a main signal of the receive signal and a second signal, which includes an image signal corresponding to the main signal, with a shift by a baud rate of the receive signal relative to the first signal in a frequency domain, a correlation calculation unit configured to calculate a cross correlation of the first signal and the second signal, and a dispersion amount calculation unit configured to calculate a wavelength dispersion amount, based on a position of a peak of the cross correlation.Type: GrantFiled: January 15, 2020Date of Patent: October 4, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo Horikoshi, Masanori Nakamura, Yoshiaki Kisaka, Seiji Okamoto, Fukutaro Hamaoka
-
Publication number: 20220303003Abstract: A signal processing apparatus includes: a coefficient update unit configured to approximate a characteristic of a transmission line of an optical signal by a first tap coefficient vector of which an LO norm is a predetermined value or less; a zeroing unit configured to generate a second tap coefficient vector by replacing, with 0, a tap coefficient of which an absolute value is less than a threshold among tap coefficients of the first tap coefficient vector; and an adaptive filter configured to perform, based on the second tap coefficient vector, adaptive equalization processing on a digital signal corresponding to an optical signal received via the transmission line.Type: ApplicationFiled: September 17, 2019Publication date: September 22, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo HORIKOSHI, Masanori NAKAMURA, Seiji OKAMOTO, Hideki NISHIZAWA, Etsushi YAMAZAKI
-
Patent number: 11444699Abstract: There are provided an optical transmission apparatus that subjects a transmission signal including a plurality of sequences to Hadamard transform to obtain a signal in which a predetermined delay is added to one of the sequences, optically modulates the obtained signal, and transmits the modulated signal, and an optical reception apparatus that demodulates a reception signal received from the optical transmission apparatus by subjecting the reception signal to adaptive equalization processing with a predetermined number of taps.Type: GrantFiled: January 15, 2020Date of Patent: September 13, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akira Masuda, Fukutaro Hamaoka, Shuto Yamamoto, Seiji Okamoto, Kengo Horikoshi, Masanori Nakamura, Asuka Matsushita, Yoshiaki Kisaka
-
Publication number: 20220224415Abstract: An electric digital received signal obtained from a received optical signal is segmented into blocks of a certain length with an overlap of a length determined in advance with an adjacent block. Fourier transformation is performed for each of the blocks. The blocks subjected to the Fourier transformation are stored consecutively in time series, a coefficient determined based on a wavelength dispersion compensation amount according to one of frequency positions and a delay amount according to one of the frequency positions and one of time positions is applied to each of frequency component values included in a plurality of the stored blocks, and the blocks to which the coefficient has been applied and which are obtained by adding up the frequency component values to which the coefficient has been applied for each of the frequency positions are generated. Inverse Fourier transformation is performed on the generated blocks to which the coefficient has been applied.Type: ApplicationFiled: June 6, 2019Publication date: July 14, 2022Inventors: Masanori NAKAMURA, Seiji Okamoto, Kengo HORIKOSHI, Shuto YAMAMOTO, Takayuki KOBAYASHI, Yoshiaki KISAKA, Masahito TOMIZAWA
-
Publication number: 20220216923Abstract: An optical transmission system according to an embodiment includes: an optical transmission unit which modulates an optical signal into which a known signal is inserted and transmits the optical signal; and an optical reception unit which receives the optical signal from the optical transmission unit, wherein the optical reception unit includes: an optical receiver which performs coherent detection of a reception signal of the optical signal received from the optical transmission unit; a receiver transfer function estimation section which estimates a nonlinear response transfer function of the optical receiver based on the known signal included in the reception signal after the detection by the optical receiver; and a receiver compensation section which compensates nonlinear distortion of the reception signal after the detection based on the nonlinear response transfer function which the receiver transfer function estimation section estimates.Type: ApplicationFiled: May 23, 2019Publication date: July 7, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Asuka MATSUSHITA, Masanori NAKAMURA, Kengo HORIKOSHI, Shoichiro KUWAHARA, Yoshiaki KISAKA
-
Patent number: 11367997Abstract: A method for manufacturing a monolithically integrated semiconductor optical integrated element comprising a DFB laser, an EA modulator, and a SOA disposed in a light emitting direction, comprising the step of forming a semiconductor wafer on which the elements are two-dimensionally arrayed and aligned the optical axes; cleaving the semiconductor wafer along a plane orthogonal to the light emitting direction to form a semiconductor bar including a plurality of the elements arranged one-dimensionally along a direction orthogonal to the light emitting direction such that the elements adjacent to each other share an identical cleavage end face as a light emission surface; inspecting the semiconductor bar by driving the SOA and the DFB laser through a connection wiring part together; and separating out the semiconductor bar after the inspection to cut the connection wiring part connecting the electrode of the SOA and the DFB laser to isolate from each other.Type: GrantFiled: February 28, 2019Date of Patent: June 21, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takahiko Shindo, Naoki Fujiwara, Kimikazu Sano, Hiroyuki Ishii, Hideaki Matsuzaki, Takashi Yamada, Kengo Horikoshi
-
Publication number: 20220158731Abstract: A wavelength dispersion amount estimation apparatus includes a correlation signal generation unit configured to generate, from a receive signal, a first signal including a main signal of the receive signal and a second signal, which includes an image signal corresponding to the main signal, with a shift by a baud rate of the receive signal relative to the first signal in a frequency domain, a correlation calculation unit configured to calculate a cross correlation of the first signal and the second signal, and a dispersion amount calculation unit configured to calculate a wavelength dispersion amount, based on a position of a peak of the cross correlation.Type: ApplicationFiled: January 15, 2020Publication date: May 19, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo HORIKOSHI, Masanori NAKAMURA, Yoshiaki KISAKA, Seiji OKAMOTO, Fukutaro HAMAOKA
-
Publication number: 20220140906Abstract: An optical transmission system includes: a first optical transmitting unit for transmitting a first optical signal having a first wavelength; a second optical transmitting unit for transmitting a second optical signal having a second wavelength; an output adjustment unit for acquiring the first optical signal and the second optical signal, adjusting signal intensities of the acquired optical signals, and outputting the optical signals; a multiplexer for multiplexing the first optical signal and the second optical signal that have been subjected to signal intensity adjustment and outputting a multiplexed signal; an amplifier for amplifying the multiplexed signal; a first optical receiving unit for receiving the amplified first optical signal; and a second optical receiving unit for receiving the amplified second optical signal.Type: ApplicationFiled: January 30, 2020Publication date: May 5, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takashi MITSUI, Toshiaki SHITABA, Akihiro TANABE, Kengo HORIKOSHI, Hisao YOSHINAGA
-
Publication number: 20220069921Abstract: There are provided an optical transmission apparatus that subjects a transmission signal including a plurality of sequences to Hadamard transform to obtain a signal in which a predetermined delay is added to one of the sequences, optically modulates the obtained signal, and transmits the modulated signal, and an optical reception apparatus that demodulates a reception signal received from the optical transmission apparatus by subjecting the reception signal to adaptive equalization processing with a predetermined number of taps.Type: ApplicationFiled: January 15, 2020Publication date: March 3, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akira MASUDA, Fukutaro HAMAOKA, Shuto YAMAMOTO, Seiji OKAMOTO, Kengo HORIKOSHI, Masanori NAKAMURA, Asuka MATSUSHITA, Yoshiaki KISAKA
-
Patent number: 11258512Abstract: A reception apparatus includes a dispersion compensation unit configured to acquire an electrical signal resulting from conversion of an optical signal and perform, on the electrical signal, dispersion compensation with a predetermined compensation amount, a clip rate measurement unit configured to measure a clip rate for the electrical signal subjected to the dispersion compensation, and a control unit configured to detect the compensation amount that minimizes the clip rate.Type: GrantFiled: May 8, 2019Date of Patent: February 22, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Seiji Okamoto, Masanori Nakamura, Kengo Horikoshi
-
Patent number: 11237334Abstract: A fiber module (1B) according to the present disclosure includes an input-side optical fiber (11), an output-side optical fiber (12), a ferrule (20) in which the input-side optical fiber and the output-side optical fiber are insertable in both ends and a groove (32) is formed in a direction orthogonal to a longitudinal direction (D1) in the middle of the longitudinal direction, a dielectric multilayer film filter (30) inserted in the groove, and an input-side GI fiber (15) and an output-side GI fiber (16) joined by fusion to respective terminal portions of the input-side optical fiber and the output-side optical fiber. The dielectric multilayer film filter is interposed between an end surface (15f) of the input-side GI fiber and an end surface (16f) of the output-side GI fiber in the longitudinal direction.Type: GrantFiled: February 28, 2019Date of Patent: February 1, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo Horikoshi, Takashi Yamada, Hisao Yoshinaga, Shunsuke Kanai, Manabu Kubota
-
Publication number: 20210218471Abstract: A reception apparatus includes a dispersion compensation unit configured to acquire an electrical signal resulting from conversion of an optical signal and perform, on the electrical signal, dispersion compensation with a predetermined compensation amount, a clip rate measurement unit configured to measure a clip rate for the electrical signal subjected to the dispersion compensation, and a control unit configured to detect the compensation amount that minimizes the clip rate.Type: ApplicationFiled: May 8, 2019Publication date: July 15, 2021Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Seiji OKAMOTO, Masanori NAKAMURA, Kengo HORIKOSHI
-
Publication number: 20210041631Abstract: A fiber module (1B) according to the present disclosure includes an input-side optical fiber (11), an output-side optical fiber (12), a ferrule (20) in which the input-side optical fiber and the output-side optical fiber are insertable in both ends and a groove (32) is formed in a direction orthogonal to a longitudinal direction (D1) in the middle of the longitudinal direction, a dielectric multilayer film filter (30) inserted in the groove, and an input-side GI fiber (15) and an output-side GI fiber (16) joined by fusion to respective terminal portions of the input-side optical fiber and the output-side optical fiber. The dielectric multilayer film filter is interposed between an end surface (15f) of the input-side GI fiber and an end surface (16f) of the output-side GI fiber in the longitudinal direction.Type: ApplicationFiled: February 28, 2019Publication date: February 11, 2021Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo HORIKOSHI, Takashi YAMADA, Hisao YOSHINAGA, Shunsuke KANAI, Manabu KUBOTA