US-12621058-B2 - Optical communication apparatus, optical communication system, and optical communication method

US12621058B2US 12621058 B2US12621058 B2US 12621058B2US-12621058-B2

Abstract

There are provided an optical communication apparatus, an optical communication system, and an optical communication method that are capable of suppressing deterioration in quality of an output signal. An optical relay apparatus includes a coherent receiver front-end unit that coherently detects an input optical signal to be input, based on local oscillation light, a coherent transmitter front-end unit that coherently modulates and outputs the coherently detected signal, a wavelength meter that monitors a characteristic of the input optical signal, and a wavelength conversion control unit that controls a characteristic of the local oscillation light, based on the monitored characteristic.

Inventors

Tatsunori OMIYA

Assignees

NEC CORPORATION

Dates

Publication Date: 20260505
Application Date: 20231026
Priority Date: 20221108

Claims (17)

1 . An optical communication apparatus comprising: a coherent detector configured to coherently detect an input optical signal to be input, based on local oscillation light; a coherent modulator configured to coherently modulate and output the coherently detected signal; a first monitor configured to select the input optical signal from a wavelength multiplexed signal and monitor a characteristic of the input optical signal; and a controller configured to control a characteristic of the local oscillation light, based on the monitored characteristic.
2 . The optical communication apparatus according to claim 1 , wherein the first monitor is configured to monitor a wavelength of the input optical signal, and wherein the controller is configured to control a wavelength of the local oscillation light, based on the monitored wavelength.
3 . The optical communication apparatus according to claim 2 , further comprising a frequency shifter configured to shift a frequency of the local oscillation light, wherein the controller is configured to control a shift amount of the frequency shifter, based on the monitored wavelength.
4 . The optical communication apparatus according to claim 1 , wherein the first monitor is configured to monitor power of the input optical signal, and wherein the controller is configured to control power of the local oscillation light or the input optical signal, based on the monitored power.
5 . The optical communication apparatus according to claim 4 , further comprising a local oscillation light source configured to output the local oscillation light, wherein the controller is configured to control output power of the local oscillation light source, based on the monitored power.
6 . The optical communication apparatus according to claim 4 , further comprising an attenuator configured to attenuate power of the input optical signal, wherein the controller is configured to control an attenuation amount of the attenuator, based on the monitored power.
7 . The optical communication apparatus according to claim 6 , further comprising a wavelength selection switch configured to select and output the input optical signal from the wavelength multiplexed signal, wherein the wavelength selection switch includes the attenuator.
8 . The optical communication apparatus according to claim 1 , further comprising a second monitor configured to monitor a characteristic of the controlled local oscillation light, wherein the controller is configured to determine whether control of the local oscillation light is completed, based on a monitor result of the second monitor.
9 . The optical communication apparatus according to claim 1 , further comprising a protector configured to execute a protection measure for protecting a subsequent-stage network of the optical communication apparatus, according to a monitor result of the first monitor.
10 . The optical communication apparatus according to claim 9 , wherein the controller is configured to stop an optical output from the coherent modulator when a protection measure of the subsequent-stage network is completed.
11 . The optical communication apparatus according to claim 9 , wherein the controller is configured to start an optical output from the coherent modulator in a case where preparation for starting reception of the subsequent-stage network is completed when the optical communication apparatus is started up.
12 . The optical communication apparatus according to claim 9 , wherein the controller is configured to stop an optical output from the coherent modulator in a case where preparation for stopping reception of the subsequent-stage network is completed when the optical communication apparatus is shut down.
13 . The optical communication apparatus according to claim 1 , wherein a wavelength of the input optical signal and a wavelength of an optical signal being output from the coherent modulation unit are different from each other.
14 . An optical communication system comprising a plurality of optical communication apparatuses, the plurality of optical communication apparatuses each including: a coherent detector configured to coherently detect an input optical signal to be input, based on local oscillation light; a coherent modulator configured to coherently modulate and output the coherently detected signal; a first monitor configured to select the input optical signal from a wavelength multiplexed signal and monitor a characteristic of the input optical signal; and a controller configured to control a characteristic of the local oscillation light, based on the monitored characteristic.
15 . The optical communication system according to claim 14 , wherein the first monitor is configured to monitor a wavelength of the input optical signal, and wherein the controller is configured to control a wavelength of the local oscillation light, based on the monitored wavelength.
16 . An optical communication method comprising: coherently detecting an input optical signal to be input, based on local oscillation light; coherently modulating and outputting the coherently detected signal; selecting the input optical signal from a wavelength multiplexed signal and monitoring a characteristic of the input optical signal; and controlling a characteristic of the local oscillation light, based on the monitored characteristic.
17 . The optical communication method according to claim 16 , wherein the monitoring a characteristic of the input optical signal includes monitoring a wavelength of the input optical signal, and wherein the controlling a characteristic of the local oscillation light includes controlling a wavelength of the local oscillation light, based on the monitored wavelength.

Description

INCORPORATION BY REFERENCE This application is based upon and claims the benefit of priority from Japanese patent application No. 2022-178557, filed on Nov. 8, 2022, the disclosure of which is incorporated herein in its entirety by reference. TECHNICAL FIELD The present disclosure relates to an optical communication apparatus, an optical communication system, and an optical communication method. BACKGROUND ART In recent years, utilization of not only wireless communication but also optical communication for various communication services is expected toward a post-5G era. Among them, studies have been carried out for enhancement of reconfigurable optical add/drop multiplexer (ROADM) networks, and in particular, attention has been paid to a wavelength-conversion technique required at a time of path change. As a related art, for example, Published Japanese Translation of PCT International Publication for Patent Application No. 2017-511036 discloses a wavelength converter that converts a wavelength of an optical signal by a reception end and a transmission end using a coherent method. SUMMARY According to Published Japanese Translation of PCT International Publication for Patent Application No. 2017-511036, in a wavelength converter, a reception end including a coherent detection front-end module converts a received optical signal into an analog electric signal, and a transmission end including an optical modulation module converts the analog electric signal into a transmitted optical signal. However, Published Japanese Translation of PCT International Publication for Patent Application No. 2017-511036 does not consider fluctuation in characteristics such as a wavelength and power of an optical signal being input, and therefore there is a problem that quality of an output signal may deteriorate. In view of such a problem, an example object of the present disclosure is to provide an optical communication apparatus, an optical communication system, and an optical communication method that are capable of suppressing deterioration in quality of an output signal. In a first example aspect according to the present disclosure, an optical communication apparatus includes: a coherent detection unit configured to coherently detect an input optical signal to be input, based on local oscillation light; a coherent modulation unit configured to coherently modulate and output the coherently detected signal; a first monitoring unit configured to monitor a characteristic of the input optical signal; and a control unit configured to control a characteristic of the local oscillation light, based on the monitored characteristic. In a second example aspect according to the present disclosure, an optical communication system includes a plurality of optical communication apparatuses, and the plurality of optical communication apparatuses each include: a coherent detection unit configured to coherently detect an input optical signal to be input, based on local oscillation light; a coherent modulation unit configured to coherently modulate and output the coherently detected signal; a first monitoring unit configured to monitor a characteristic of the input optical signal; and a control unit configured to control a characteristic of the local oscillation light, based on the monitored characteristic. In a third example aspect according to the present disclosure, an optical communication method includes: coherently detecting an input optical signal to be input, based on local oscillation light; coherently modulating and outputting the coherently detected signal; monitoring a characteristic of the input optical signal; and controlling a characteristic of the local oscillation light, based on the monitored characteristic. BRIEF DESCRIPTION OF DRAWINGS The above and other aspects, features, and advantages of the present disclosure will become more apparent from the following description of certain example embodiments when taken in conjunction with the accompanying drawings, in which: FIG. 1 is a configuration diagram illustrating a configuration example of an optical communication system according to some example embodiments; FIG. 2 is a configuration diagram illustrating a configuration example of a related optical relay apparatus; FIG. 3 is a characteristic diagram for describing a problem of the related optical relay apparatus; FIG. 4 is a characteristic diagram for describing a problem of the related optical relay apparatus; FIG. 5 is a configuration diagram illustrating a schematic configuration of an optical relay apparatus according to some example embodiments; FIG. 6 is a configuration diagram illustrating a specific configuration example of the optical relay apparatus according to some example embodiments; FIG. 7 is a configuration diagram illustrating a configuration example of an optical frequency shifter according to some example embodiments; FIG. 8 is a configuration diagram illustrating a configuration example of a coherent rec