Optical signal processing device, tap coefficient update method, program, and optical signal processing system

Patent metadata

Field	Value
Publication number	US-2025337517-A1
Application number	US-202218861234-A
Country	US
Kind code	A1
Filing date	May 18, 2022
Priority date	May 18, 2022
Publication date	Oct 30, 2025
Grant date	—

Abstract

An optical signal processing device includes: a polarization separator that separates an input polarization multiplexed signal; an optical coupler that branches one polarization component; an optical coupler that branches another polarization component; optical filters to which the one polarization component branched by the optical coupler is input; optical filters to which the other polarization component branched by the optical coupler is input; an optical coupler that multiplexes outputs of the optical filters; an optical coupler that multiplexes outputs of the optical filters; and a tap coefficient update unit that adaptively sets tap coefficients of the optical filters to separate a polarization multiplexed signal.

First claim

1 . An optical signal processing device comprising:
a polarization separator configured to separate an input polarization multiplexed signal into two polarization components; a first optical coupler configured to branch one polarization component separated by the polarization separator; a second optical coupler configured to branch another polarization component separated by the polarization separator; first and second optical filters to which the one polarization component branched by the first optical coupler is input; third and fourth optical filters to which the other polarization component branched by the second optical coupler is input; a third optical coupler configured to multiplex outputs of the first and the third optical filters; a fourth optical coupler configured to multiplex outputs of the second and the fourth optical filters; and a tap coefficient update unit configured to adaptively set tap coefficients of the first to the fourth optical filters to separate a polarization multiplexed signal.

2 . The optical signal processing device according to claim 1 , wherein each of the first to the fourth optical filters includes:
an optical demultiplexer configured to demultiplex an optical signal at predetermined phase intervals; a plurality of optical phase shifters configured to control phases of respective frequency components of optical signals demultiplexed by the optical demultiplexer; a plurality of optical attenuators configured to control amplitudes of respective optical signals with the phases controlled by the respective optical phase shifters; and an optical multiplexer configured to multiplex optical signals output from the plurality of optical attenuators.

3 . The optical signal processing device according to claim 1 , wherein
the tap coefficient update unit is configured to adaptively set coefficients of the first to the fourth optical filters so as to output a signal obtained by applying a moving average filter to the input polarization multiplexed signal.

4 . A tap coefficient update method comprising:
detecting, by a detector, an output signal of a polarization separator that separates an input polarization multiplexed signal into two polarization components; detecting, by the detector, an output signal obtained by multiplexing output signals of optical filters connected to the polarization separator in a butterfly type; calculating, by a control unit, as an error signal, a difference between a predetermined amplitude and an output signal obtained by multiplexing the output signals of the optical filters; and calculating, by the control unit, tap coefficients of the optical filters based on the error signal, the output signal of the polarization separator, and the output signal obtained by multiplexing the output signals of the optical filters.

5 . A non-transitory computer readable medium storing a program that causes a computer to perform operations comprising:
detecting an output signal of a polarization separator that separates an input polarization multiplexed signal into two polarization components; detecting an output signal obtained by multiplexing output signals of optical filters connected to the polarization separator in a butterfly type; calculating, as an error signal, a difference between a predetermined amplitude and an output signal obtained by multiplexing the output signals of the optical filters; and calculating tap coefficients of the optical filters based on the error signal, the output signal of the polarization separator, and the output signal obtained by multiplexing the output signals of the optical filters.

6 . (canceled)

7 . (canceled)

Assignees

• Nippon Telegraph & Telephone

Inventors

• Matsuda Toshiya
• Nakagawa Masahiro
• Masumoto Kana
• Nishiyama Kota

Classifications

• H04J14/02

  Wavelength-division multiplex systems · CPC title

• G02B27/286

  for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another (G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34) · CPC title

• H04B10/614

  comprising one or more polarization beam splitters, e.g. polarization multiplexed [PolMux] X-PSK coherent receivers, polarization diversity heterodyne coherent receivers (H04J14/06 takes precedence) · CPC title

• H04J14/06 Primary

  Polarisation multiplex systems · CPC title

• H04B10/67

  Optical arrangements in the receiver · CPC title