Optical transmission apparatus and optical attenuation amount control method

• US 20090297143A1
• Filed: 04/28/2009
• Published: 12/03/2009
• Est. Priority Date: 05/29/2008
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Takeyama, Tomoaki, Hayashi, Etsuko, Muro, Shinichirou, Nakajima, Ichiro, Sasaki, Keiko
• Granted Patent: US 8,116,626 B2
• Time in Patent Office: Days
• US Class Current: 398/34
• CPC Class Codes: H04B 10/07955 Monitoring or measuring power
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant

Abstract

In an optical transmission apparatus, levels of signal lights obtained by demultiplexing a WDM signal and corresponding to channels are detected, based on which a channel in which a signal is transmitted and a channel in which no signal is transmitted are determined. An attenuation amount of a channel in which no signal is transmitted in a predetermined range from the channel in which the signal is transmitted is set to a value equal to an attenuation amount of the channel in which the signal is transmitted. An attenuation amount of a channel in which no signal is transmitted out of the predetermined range from the channel in which the signal is transmitted is set to a value larger than the attenuation amount of the channel in which the signal is transmitted. The signal lights are attenuated based on the values and multiplexed.

Claims

1. An optical transmission apparatus comprising:

a first determining unit that determines to set an attenuation amount of a channel within a predetermined wavelength range from a channel in which a signal is transmitted, out of channels in which no signal is transmitted, to a value equal to an attenuation amount of the channel in which the signal is transmitted;

a second determining unit that determines to set an attenuation amount of a channel out of the predetermined wavelength range from a channel in which a signal is transmitted, out of the channels in which no signal is transmitted, to a value larger than the attenuation amount of the channel in which the signal is transmitted; and

a variable optical attenuator that attenuates the signal lights of the respective channels based on the values determined by the first determining unit and the second determining unit.

2. The optical transmission apparatus according to claim 1, wherein the predetermined wavelength range is a wavelength range of ±

2.5 nanometers.

3. The optical transmission apparatus according to claim 1, wherein the second determining unit determines to set the attenuation amount of the channel out of the predetermined wavelength range from the channel in which the signal is transmitted, out of the channels in which no signal is transmitted, to a maximum attenuation amount of the variable optical attenuator.

4. The optical transmission apparatus according to claim 1, wherein the first determining unit determines to set the attenuation amount of the channel within the predetermined wavelength range from the channel in which the signal is transmitted, out of the channels in which no signal is transmitted, to a minimum attenuation amount of the variable optical attenuator.

5. An optical attenuation amount control method comprising:

first determining to set an attenuation amount of a channel within a predetermined wavelength range from the channel in which a signal is transmitted, out of channels in which no signal is transmitted, to a value equal to an attenuation amount of the channel in which the signal is transmitted;

second determining to set an attenuation amount of a channel out of the predetermined wavelength range from the channel in which the signal is transmitted, out of the channels in which no signal is transmitted, to a value larger than the attenuation amount of the channel in which the signal is transmitted; and

attenuating the signal lights of the respective channels based on the values determined at the first determining and the second determining.

6. The optical attenuation amount control method according to claim 5, wherein the predetermined wavelength range is a wavelength range of ±

2.5 nanometers.

7. The optical attenuation amount control method according to claim 5, wherein the second determining includes determining to set the attenuation amount of the channel out of the predetermined wavelength range from the channel in which the signal is transmitted, out of the channels in which no signal is transmitted, to a maximum attenuation amount of the attenuating.

8. The optical transmission apparatus according to claim 5, wherein the first determining includes determining to set the attenuation amount of the channel within the predetermined wavelength range from the channel in which the signal is transmitted, out of the channels in which no signal is transmitted, to a minimum attenuation amount of the attenuating.