Optical transmission line switching apparatus and optical transmission system

Patent metadata

Field	Value
Publication number	US-9628173-B2
Application number	US-201314897115-A
Country	US
Kind code	B2
Filing date	Oct 4, 2013
Priority date	Oct 4, 2013
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

A device includes a threshold setting unit that sets a threshold for an input optical power monitor to detect the input optical power to the optical transmission line of an active system; a threshold deciding unit that decides whether the input optical power to the optical transmission line of the active system detected by the input optical power monitor is not greater than the threshold set by the threshold setting unit or not; and an attenuation controller that carries out, when the threshold deciding unit decides that the input optical power is not greater than the threshold, system switching by controlling first variable optical attenuators so as to gradually reduce attenuation of the signal light rays input from the optical transmission line of one backup system, and to gradually increase attenuation of the signal light rays input from the optical transmission line of the active system.

First claim

What is claimed is:

1. An optical transmission line switching apparatus to carry out system switching between an optical transmission line of a single active system and an optical transmission line of at least one backup system, the optical transmission line switching apparatus comprising:
input optical power monitors that are provided to the optical transmission lines, respectively, to monitor input optical powers of signal light rays input from the optical transmission lines;
first variable optical attenuators that are placed downstream of the input optical power monitors, respectively, to attenuate and output the signal light rays input from the optical transmission lines;
a multiplexer to multiplex the signal light rays output from the first variable optical attenuators;
a threshold setter to set a threshold for the input optical power monitor to detect the input optical power to the optical transmission line of the active system;
a threshold decider to decide whether the input optical power to the optical transmission line of the active system detected by the input optical power monitor is not greater than the threshold set by the threshold setter or not; and
an attenuation controller to carry out, when the threshold decider decides that the input optical power is not greater than the threshold, system switching by controlling the first variable optical attenuators so as to gradually reduce attenuation of the signal light rays input from the optical transmission line of the at least one backup system, and to gradually increase attenuation of the signal light rays input from the optical transmission line of the active system.

2. The optical transmission line switching apparatus according to claim 1 , further comprising:
an output optical power monitor that are placed at an output side of the multiplexer to monitor output optical power from the multiplexer, wherein
the attenuation controller controls, when the threshold decider decides that the input optical power is not greater than the threshold, the first variable optical attenuators so as to maintain the output optical power at a set point by reducing the attenuation of the signal light rays input from the optical transmission line of the at least one backup system, and by increasing the attenuation of the signal light rays input from the optical transmission line of the active system.

3. The optical transmission line switching apparatus according to claim 1 , further comprising:
optical amplifiers that are placed between the input optical power monitors and the first variable optical attenuators on the optical transmission lines, respectively, to amplify the signal light rays input from the optical transmission lines.

4. The optical transmission line switching apparatus according to claim 2 , wherein
the threshold setter sets the threshold within a region of the input optical power, in which the attenuation controller is able to regulate the first variable optical attenuators so as to maintain the output optical power at the set point.

5. The optical transmission line switching apparatus according to claim 1 , further comprising:
second variable optical attenuators that are placed between the input optical power monitors and the first variable optical attenuators on the optical transmission lines, respectively, to attenuate and then output the signal light rays input from the optical transmission lines; and
first intermediate optical power monitors that are placed downstream of the second variable optical attenuators, respectively, to monitor the output optical powers of the output light rays output by the second variable optical attenuators, wherein
the attenuation controller controls the second variable optical attenuators so as to maintain the output optical powers the first intermediate optical power monitors monitor at set points.

6. The optical transmission line switching apparatus according to claim 1 , further comprising:
optical amplifiers that are placed between the input optical power monitors and the first variable optical attenuators on the optical transmission lines, respectively, to amplify the signal light rays input from the optical transmission lines; and
second intermediate optical power monitors that are placed downstream of the optical amplifiers, respectively, to monitor the output optical powers of the output light rays output from the optical amplifiers, wherein
the attenuation controller controls the optical amplifiers so as to maintain the output optical powers the second intermediate optical power monitors monitor at set points.

7. The optical transmission line switching apparatus according to claim 5 , wherein
the threshold setter sets the threshold within a region of the input optical power, in which the attenuation controller is able to control the second variable optical attenuators so as to maintain the output optical powers the first intermediate optical power monitors monitor at the set points.

8. The optical transmission line switching apparatus according to claim 6 , wherein
the threshold setter sets the threshold within a region of the input optical power, in which the attenuation controller is able to control the optical amplifiers so as to maintain the output optical powers the second intermediate optical power monitors monitor at the set points.

9. The optical transmission line switching apparatus according to claim 1 , wherein
the first variable optical attenuators are similar variable optical attenuator devices with characteristics complementary to each other;
the optical transmission line switching apparatus further comprises a bias application circuit to apply a voltage or current to the first variable optical attenuators; and
the attenuation controller controls, when the threshold decider decides that the input optical power is not greater than the threshold, the first variable optical attenuators by controlling a voltage or current applied to the bias application circuit so as to gradually reduce the attenuation of the signal light rays input from the optical transmission line of at least one backup system, and to gradually increase the attenuation of the signal light rays input from the optical transmission line of the active system.

10. The optical transmission line switching apparatus according to claim 9 , further comprising:
second variable optical attenuators that are placed between the input optical power monitors and the first variable optical attenuators on the optical transmission lines, respectively, to attenuate and then output the signal light rays input from the optical transmission lines; and
first intermediate optical power monitors that are placed downstream of the second variable optical attenuators, respectively, to monitor the output optical powers of the output light rays output by the second variable optical attenuators, wherein
the attenuation controller controls the second variable optical attenuators so as to equalize the output optical powers the first intermediate optical power monitors monitor.

11. The optical transmission line switching apparatus according to claim 9 , further comprising:
optical amplifiers that are placed between the input optical power monitors and the first variable optical attenuators on the optical transmission lines, respectively, to amplify the signal light rays input from the optical transmission lines; and
second intermediate optical power monitors that are placed downstream of the optical amplifiers, respectively, to monitor the output optical powers of the output light rays output by the optical amplifiers, wherein
the attenuation controller controls the optical amplifiers so as to equalize the output optica

Assignees

• Mitsubishi Electric Corp

Inventors

• Tokura Toshiyuki
• Chikamori Shun

Classifications

• H04J14/0221

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

• H04Q11/0005

  Switch and router aspects · CPC title

• H04B10/032 Primary

  using working and protection systems {(H04J14/0287 takes precedence)} · CPC title

• H04J14/0227

  Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation · CPC title

• H04Q2011/0016

  using wavelength multiplexing or demultiplexing · CPC title