Optical receiver and superimposed signal detecting method

Patent metadata

Field	Value
Publication number	US-9838148-B2
Application number	US-201615095698-A
Country	US
Kind code	B2
Filing date	Apr 11, 2016
Priority date	May 14, 2015
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

An optical receiver includes: a tunable filter configured to partially transmit a wavelength-multiplexed optical-signal including a first optical-signal having a first wavelength, a second optical-signal having a second wavelength, and a third optical-signal having a third wavelength, with a frequency-modulated signal superimposed on each of the first to third optical-signals; a photo detector configured to detect an optical-power of the wavelength-multiplexed optical-signal transmitted through the tunable filter; and a superimposed signal detector configured to detect the frequency-modulated signal superimposed on the first optical-signal, based on an amplitude-modulated signal according to a variation in the optical-power on a first filter setting where both of the first optical-signal and the second optical-signal transmit through the tunable filter, and an amplitude-modulated signal according to a variation in the optical-power on a second filter setting where both of the first optical-signal and the third optical-signal transmit through the tunable filter.

First claim

What is claimed is:

1. An optical receiver comprising:
a tunable filter configured to partially transmit a wavelength-multiplexed optical signal including a first optical signal having a first wavelength, a second optical signal having a second wavelength adjacent to a short wavelength side of the first wavelength, and a third optical signal having a third wavelength adjacent to a long wavelength side of the first wavelength, each of the first to third optical signals being superimposed with a frequency-modulated signal indicating a path ID of an optical path;
a photodetector configured to receive the frequency-modulated signal transmitted through the tunable filter and convert the frequency-modulated signal into an electrical signal; and
a controller configured to control an overall operation of the optical receiver and including a filtering controller, an optical power detector, an orthogonal code detector, and a path ID detector,
wherein the filtering controller changes a transmission center frequency of the tunable filter such that
the tunable filter is set for a first filter setting in which the transmission center frequency is set between the first optical signal and the second optical signal so that portions of only the first optical signal and the second optical signal transmit through the tunable filter, or for a second filter setting in which the transmission center frequency is set between the first optical signal and the third optical signal so that portions of only the first optical signal and the third optical signal transmit through the tunable filter,
the optical power detector detects an amplitude-modulated signal component of the frequency-modulated signal which has been converted into the electrical signal at the photodetector for each of the first optical signal and the second optical signal for the first filter setting and for each of the first optical signal and the third optical signal for the second filter setting,
the orthogonal code detector detects an orthogonal code of the frequency-modulated signal which has been converted into the electrical signal at the photodetector for each of the first and second optical signals for the first filter setting and for each of the first and third optical signals for the second filter setting, and
the path ID detector detects the path ID of the first optical signal by comparing the amplitude-modulated signal component for each of the first and second optical signals for the first filter setting and for each of the first and third optical signals for the second filter setting.

2. The optical receiver according to claim 1 , wherein the frequency-modulated signal superimposed on each of the first to third optical signals is orthogonally-coded by the orthogonal code, and wherein the optical power detector identifies an amplitude-modulated signal corresponding to the frequency-modulated signal superimposed on the first optical signal based on the orthogonal code.

3. The optical receiver according to claim 1 , wherein the filtering controller sweeps the transmission center frequency on each of the first filter setting and the second filter setting.

4. The optical receiver according to claim 1 , wherein the frequency-modulated signal superimposed on each of the first to third optical signals is differentially-coded, and wherein the optical power detector detects the frequency-modulated signal superimposed on the first optical signal by differentially-decoding the amplitude-modulated signal detected on each of the first filter setting and the second filter setting.

5. A superimposed signal detecting method comprising:
receiving, at a tunable filter, a wavelength-multiplexed optical signal including a first optical signal having a first wavelength, a second optical signal having a second wavelength adjacent to a short wavelength side of the first wavelength, and a third optical signal having a third wavelength adjacent to a long wavelength side of the first wavelength, each of the first to third optical signals being superimposed with a frequency-modulated signal indicating a path ID of an optical path;
setting a transmission center frequency of the tunable filter for a first filter setting in which the transmission center frequency is set between the first optical signal and the second optical signal so that portions of only the first optical signal and the optical second signal transmit through the tunable filter, and for a second filter setting in which the transmission center frequency is set between the first optical signal and the third optical signal so that portions of only the first optical signal and the third optical signal transmit through the tunable filter;
partially transmitting the wavelength-multiplexed optical signal through the tunable filter for each of the first filter setting and the second filter setting thereby obtaining the frequency modulated signal for each of the first and second optical signals of the first filter setting and for each of the first and third optical signals of the second filter setting;
converting, by a photodetector, the frequency modulated signal into an electrical signal for each of the first and second optical signals of the first filter setting and for each of the first and third optical signals of the second filter setting;
detecting, by an optical power detector, an amplitude-modulated signal component of the frequency-modulated signal which has been converted into the electrical signal at the photodetector for each of the first optical signal and the second optical signal for the first filter setting and for each of the first optical signal and the third optical signal for the second filter setting;
detecting, by an orthogonal detector, an orthogonal code of the frequency-modulated signal which has been converted into the electrical signal at the photodetector for each of the first and second optical signals for the first filter setting and for each of the first and third optical signals for the second filter setting; and
comparing, by a path ID, the amplitude-modulated signal component for each of the first and second optical signals for the first filter setting and for each of the first and third optical signals for the second filter setting, thereby detecting the path ID.

Assignees

• Fujitsu Ltd

Inventors

• Nakagawa Goji
• Yamauchi Tomohiro
• Huang Guoxiu
• Yoshida Setsuo
• Oda Shoichiro
• Sone Kyosuke
• Aoki Yasuhiko

Classifications

• H04J14/0221 Primary

  Power control, e.g. to keep the total optical power constant · CPC title

• H04B10/25

  Arrangements specific to fibre transmission · CPC title

• H04J14/0278

  WDM optical network architectures · CPC title

• H04B10/077 Primary

  using a supervisory or additional signal · CPC title