Coherent optical receiver device and coherent optical receiving method

Patent metadata

Field	Value
Publication number	US-2020313776-A1
Application number	US-202016901796-A
Country	US
Kind code	A1
Filing date	Jun 15, 2020
Priority date	Nov 18, 2010
Publication date	Oct 1, 2020
Grant date	—

Abstract

In a coherent optical receiver device, the dynamic range considerably decreases in the case of selectively receiving the optical multiplexed signals by means of the wavelength of the local oscillator light, therefore, a coherent optical receiver device according to an exemplary aspect of the invention includes a coherent optical receiver receiving optical multiplexed signals in a lump in which signal light is multiplexed; a variable optical attenuator; a local oscillator connected to the coherent optical receiver; and a first controller controlling the variable optical attenuator by means of a first control signal based on an output signal of the coherent optical receiver; wherein the coherent optical receiver includes a 90-degree hybrid circuit, a photoelectric converter, and an impedance conversion amplifier, and selectively detects the signal light interfering with local oscillation light output by the local oscillator out of the optical multiplexed signals; and the variable optical attenuator is disposed in the optical path of the optical multiplexed signals in a stage preceding the photoelectric converter, inputs the optical multiplexed signals, and outputs them to the coherent optical receiver controlling the intensity of the optical multiplexed signals based on the first control signal.

First claim

1 - 6 . (canceled)

7 . An optical module, comprising:
an optical light source configured to output local oscillation light; a variable optical attenuator configured to attenuate input multiplexed signals including a plurality of optical signals; a coherent hybrid mixer configured to receive one of the plurality of optical signals by interfering with the local oscillation light; and a photoelectric converter configured to convert the received optical signal into a converted signal, wherein the variable optical attenuator is further configured to attenuate the input multiplexed signals based on both an electrical signal and optical intensity of the input multiplexed signals, the electrical signal being downstream of the photoelectric converter.

8 . The optical module of claim 7 , further comprising:
an optical splitter configured to obtain a part of the optical intensity of the input multiplexed signals; and an optical power monitor configured to monitor the part of the optical intensity, wherein the variable optical attenuator is further configured to attenuate the input multiplexed signals based on amplitude of the electrical signal and a monitoring result by the optical power monitor.

9 . The optical module of claim 7 , further comprising:
a polarization optical splitter configured to split the input multiplexed signals into first polarization signals and second polarization signals; and a second optical splitter configured to split the local oscillation light into a first split light and a second split light, wherein the coherent hybrid mixer is further configured to receive one of the first polarization signals and one of the second polarization signals by interfering with the first split light and the second split light, respectively.

10 . The optical module of claim 7 , wherein the variable optical attenuator is further configured to attenuate the input multiplexed signals based on amplifier gain for the electrical signal.

11 . The optical module of claim 7 , wherein the variable optical attenuator is further configured to attenuate the input multiplexed signals based on a limit optical intensity of the photoelectric converter.

12 . The optical module of claim 7 , wherein the photoelectric converter comprises a photo diode.

13 . The optical module of claim 7 , wherein the variable optical attenuator is further configured to attenuate the input multiplexed signals based on a limit electrical amplitude of the electrical signal.

14 . The optical module of claim 7 , wherein the variable optical attenuator is further configured to attenuate the input multiplexed signals so as to prevent the coherent hybrid mixer from receiving an excessive optical signal.

15 . A method of receiving input multiplexed signals, the input multiplexed signals comprising a plurality of optical signals and the method comprising:
outputting a local oscillation light; attenuating the input multiplexed signals; receiving one of the plurality of optical signals by interfering with the local oscillation light; and converting the received optical signal into a converted signal, wherein the attenuating of the input multiplexed signals includes attenuating the input multiplexed signals based on both an electrical signal and optical intensity of the input multiplexed signals, the electrical signal being downstream of the converted signal.

16 . The method of claim 15 , further comprising:
obtaining a part of the optical intensity of the input multiplexed signals; monitoring the part of the optical intensity; and attenuating the input multiplexed signals based on amplitude of the electrical signal and a monitoring result.

17 . The method of claim 15 , further comprising:
splitting the input multiplexed signals into first polarization signals and second polarization signals; splitting the local oscillation light into a first split light and a second split light; and receiving one of the first polarization signals and one of the second polarization signals by interfering with the first split light and the second split light, respectively.

18 . The method of claim 15 , further comprising attenuating the input multiplexed signals based on amplifier gain for the electrical signal.

19 . The method of claim 15 , further comprising attenuating the input multiplexed signals based on a limit optical intensity of a photoelectric converter.

20 . The method of claim 15 , wherein the converting is performed using a photo diode.

21 . The method of claim 15 , further comprising attenuating the input multiplexed signals based on a limit electrical amplitude of the electrical signal.

22 . The method of claim 15 , wherein the receiving is performed using a coherent hybrid mixer.

23 . The method of claim 15 , further comprising attenuating the input multiplexed signals so as to prevent input of excessive optical signal.

Assignees

• Nec Corp

Inventors

• Suzuki Kouichi

Classifications

• 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

• H04B10/612 Primary

  for optical signals modulated with a format different from binary or higher-order PSK [X-PSK], e.g. QAM, DPSK, FSK, MSK, ASK · CPC title

• H04B10/613

  including phase diversity, e.g., having in-phase and quadrature branches, as in QPSK coherent receivers · CPC title

• H04B10/0795

  Performance monitoring; Measurement of transmission parameters · CPC title

• H04B10/615

  Arrangements affecting the optical part of the receiver · CPC title