Optical transmission system, controller for wavelength tunable filter, and control method of wavelength tunable filter

Patent metadata

Field	Value
Publication number	US-9876601-B2
Application number	US-201615264894-A
Country	US
Kind code	B2
Filing date	Sep 14, 2016
Priority date	Sep 24, 2015
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

There is proved an optical transmission system including: a transmitter configured to transmit an optical signal modulated with a discrete multi-tone (DMT) drive signal; a filter capable of changing a wavelength of the optical signal input from the transmitter; a monitor configured to monitor a power of the optical signal passed through the filter; and at least one processor configured to: set a center wavelength of the filter, shift the center wavelength, detect a change in the power monitored by the monitor, identify a carrier component of the optical signal based on the change in the power, and control a relative relationship between a transmission characteristic of the filter and a wavelength of the carrier component so that the carrier component is included in the optical signal and one of an upper sideband and a lower sideband of the optical signal is at least partially removed by the filter.

First claim

What is claimed is:

1. An optical transmission system comprising:
an optical transmitter configured to transmit an optical signal modulated with a discrete multi-tone (DMT) drive signal;
a wavelength tunable filter capable of changing a wavelength of the optical signal input from the optical transmitter;
a power monitor configured to monitor a power of the optical signal passed through the wavelength tunable filter; and
at least one processor configured to:
set a center wavelength of the wavelength tunable filter,
shift the center wavelength,
detect a change in the power monitored by the power monitor,
identify an optical main carrier component of the optical signal based on the change in the power, and
control a relative relationship between a transmission characteristic of the wavelength tunable filter and a wavelength of the optical main carrier component so that the optical main carrier component is included in the optical signal and one of an upper sideband and a lower sideband of the optical signal is at least partially removed by the wavelength tunable filter.

2. The optical transmission system according to claim 1 ,
wherein the at least one processor controls the relative relationship:
to shift a wavelength band of an optical signal at which the optical signal passes through the wavelength tunable filter to a long-wavelength side, and
to shift the wavelength band of the optical signal at which the optical signal passes through the wavelength tunable filter to a short-wavelength side, when the change in the power resulting from an intensity ratio of a power of the optical main carrier component to a power of a DMT modulation component that is a component other than the optical main carrier component in the optical signal passed through the wavelength tunable filter is detected.

3. The optical transmission system according to claim 1 ,
wherein the at least one processor controls the relative relationship:
to narrow a wavelength bandwidth of the optical signal at which the optical signal passes through the wavelength tunable filter, and
widen the wavelength bandwidth of the optical signal at which the optical signal passes through the wavelength tunable filter, when the change in the power resulting from an intensity ratio of a power of the optical main carrier component to a power of a DMT modulation component that is a component other than the optical main carrier component in the optical signal passed through the wavelength tunable filter is detected.

4. The optical transmission system according to claim 1 ,
wherein the at least one processor controls the transmission characteristic of the wavelength tunable filter:
to set a passband of the wavelength tunable filter so that the passband includes a wavelength band where transmittance is partly relatively low within a wavelength band of the optical signal, and
to include, when a wavelength band where the power of the optical signal passed through the wavelength tunable filter is relatively low is detected, the detected wavelength band of the optical signal in a vestigial sideband obtained by the removing the one of the upper sideband and the lower sideband of the optical signal.

5. The optical transmission system according to claim 1 ,
wherein the at least one processor controls the relative relationship to set a passband of the wavelength tunable filter to be a passband of the wavelength tunable filter at a time when a change in the power of the optical signal passed through the wavelength tunable filter by detecting an extremal of a deterioration amount of the power is detected, in a case where a width of the passband of the wavelength tunable filter is changed within a range where the deterioration amount is equal to or less than a predetermined amount.

6. The optical transmission system according to claim 1 ,
wherein the at least one processor controls the transmission characteristic of the wavelength tunable filter:
to change an attenuation amount of the power of the optical signal passing through the wavelength tunable filter, and
based on the attenuation amount and a difference between a wavelength for which the change in the power is detected and a center wavelength of the optical signal passing through the wavelength tunable filter.

7. The optical transmission system according to claim 1 , further comprising:
a plurality of optical transmitters configured to transmit a plurality of optical signals having different wavelengths; and
a wavelength multiplexing transmitter configured to multiplex the plurality of optical signals transmitted from the plurality of optical transmitters so as to generate a wavelength-multiplexed optical signal,
wherein the wavelength tunable filter receives the wavelength-multiplexed optical signal, and
wherein the at least one processor controls the relative relationship on at least one of the plurality of optical signals included in the wavelength-multiplexed optical signal.

8. A controller for a wavelength tunable filter capable of changing a wavelength of an optical signal modulated with a discrete multi-tone (DMT) drive signal, the controller comprising:
a power monitor configured to monitor a power of the optical signal passed through the wavelength tunable filter; and
at least one processor configured to:
set a center wavelength of the wavelength tunable filter,
shift the center wavelength,
detect a change in the power monitored by the power monitor,
identify an optical main carrier component of the optical signal based on the change in the power, and
control a relative relationship between a transmission characteristic of the wavelength tunable filter and a wavelength of the optical main carrier component so that the optical main carrier component is included in the optical signal and one of an upper sideband and a lower sideband of the optical signal is at least partially removed by the wavelength tunable filter.

9. The controller according to claim 8 ,
wherein the at least one processor controls the relative relationship:
to shift a wavelength band of an optical signal at which the optical signal passes through the wavelength tunable filter to a long-wavelength side, and
to shift the wavelength band of the optical signal at which the optical signal passes through the wavelength tunable filter to a short-wavelength side, when the change in the power resulting from an intensity ratio of a power of the optical main carrier component to a power of a DMT modulation component that is a component other than the optical main carrier component in the optical signal passed through the wavelength tunable filter is detected.

10. The controller according to claim 8 ,
wherein the at least one processor controls the relative relationship:
to narrow a wavelength bandwidth of the optical signal at which the optical signal passes through the wavelength tunable filter, and
widen the wavelength bandwidth of the optical signal at which the optical signal passes through the wavelength tunable filter, when the change in the power resulting from an intensity ratio of a power of the optical main carrier component to a power of a DMT modulation component that is a component other than the optical main carrier component in the optical signal passed through the wavelength tunable filter is detected.

11. The controller according to claim 8 ,
wherein the at least one processor controls the transmission characteristic of the wavelength tunable filter:
to set a passband of the wavelength tunable filter so that the passband includes a wavelength band where transmittance is partly relatively low within a wavelength band of the optical signal, and
to include, when a wavelen

Assignees

• Fujitsu Ltd

Inventors

• Tanaka Toshiki
• Okabe Ryou
• Takahara Tomoo
• Nishihara Masato
• Kai Yutaka

Classifications

• H04B10/572

  Wavelength control · CPC title

• H04B10/564 Primary

  Power control · CPC title

• H04J14/0221 Primary

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

• H04J14/02216

  by gain equalization · CPC title

• H04B10/07957 Primary

  Monitoring or measuring wavelength · CPC title