Optical regenerator in optical fiber communication system

• US 7,773,886 B2
• Filed: 06/30/2003
• Issued: 08/10/2010
• Est. Priority Date: 06/30/2003
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Hainberger, Rainer, Watanabe, Shigeki
• Primary Examiner(s): Tran; Dzung D
• Application Number:
  US10/595,023
• Publication Number:
  US 20070104491A1
• Time in Patent Office: 2,598 Days
• Field of Search: 398/31, 398/37, 398/97, 398173-181, 398/197
• US Class Current: 398/97
• CPC Class Codes: H04B 10/2942 using automatic gain control [AGC] H04B10/296 takes precedence

Abstract

In an optical fiber communication system, the input power to an all-optical nonlinear device in an optical regenerator is monitored and adjusted such that the regenerator operates at an optimized operation point.

Claims

1. An optical fiber transmission system comprising an optical transmitter, an optical receiver, an optical fiber to connect the transmitter with the receiver, a plurality of optical amplifiers along the optical fiber to compensate absorption losses of a signal light passing through the optical fiber, and at least one optical regenerator,

wherein the optical regenerator including:

an optical amplifier at an input of the regenerator;

an all-optical nonlinear device to provide a nonlinear transfer function between optical input power of an optical signal after the optical amplifier and optical output power of an optical signal after the nonlinear device;

an adjusting device to receive the optical signal after the nonlinear device, adjust the optical output power of the optical signal after the nonlinear device to a level of launch power from the regenerator, and output an adjusted optical signal;

a first monitoring device including a photodiode to measure the optical input power of the optical signal after the optical amplifier and output a first monitoring signal;

a second monitoring device to monitor an optical signal after the adjusting device and output a second monitoring signal; and

a control unit to receive the first and second monitoring signals, control the optical amplifier based on the first monitoring signal to adjust an optical input power to the nonlinear device to a preset value, control the adjusting device based on the second monitoring signal, and communicate with one of another optical regenerator and a receiver via an optical supervisory channel,

wherein a target value of an average input power to the nonlinear device detected by the photodiode is set as the preset value at a time of installation of the regenerator in the optical fiber transmission system,

wherein the optical input power to the nonlinear device of each regenerator is adjusted such that a bit error rate at the receiver is minimized and an adjusted value is stored as the target value at the time of installation,

wherein a procedure of setting the target value is performed in backward direction starting from a regenerator closest to the receiver, and

wherein the optical supervisory channel is used for communication between a location of the receiver and each regenerator.

2. An optical fiber transmission system comprising an optical transmitter, an optical receiver, an optical fiber to connect the transmitter with the receiver, a plurality of optical amplifiers along the optical fiber to compensate absorption losses of a signal light passing through the optical fiber, and at least one optical regenerator,

wherein the optical regenerator including:

an optical amplifier at an input of the regenerator;

an all-optical nonlinear device to provide a nonlinear transfer function between optical input power of an optical signal after the optical amplifier and optical output power of an optical signal after the nonlinear device;

an adjusting device to receive the optical signal after the nonlinear device, adjust the optical output power of the optical signal after the nonlinear device to a level of launch power from the regenerator, and output an adjusted optical signal;

a first monitoring device including a photodiode to measure the optical input power of the optical signal after the optical amplifier and output a first monitoring signal;

a second monitoring device to monitor an optical signal after the adjusting device and output a second monitoring signal; and

a control unit to receive the first and second monitoring signals, control the optical amplifier based on the first monitoring signal to adjust an optical input power to the nonlinear device to a preset value, control the adjusting device based on the second monitoring signal, and communicate with one of another optical regenerator and a receiver via an optical supervisory channel,

wherein a target value of an average input power to the nonlinear device detected by the photodiode is set as the preset value at a time of installation of the regenerator in the optical fiber transmission system,

wherein the optical input power to the nonlinear device of each regenerator is adjusted such that a bit error rate before a nonlinear device in a subsequent regenerator or at the receiver in case of the last regenerator is minimized and an adjusted value is stored as the target value at the time of installation, and

wherein a procedure of setting the target value is performed in forward direction starting from a regenerator closest to the transmitter.

3. A reconfigurable optical network comprising optical transmitters, optical receivers, at least one optical reconfigurable network node, optical fibers to connect the transmitters with the receivers via the reconfigurable nodes, a plurality of optical amplifiers along the optical fibers to compensate absorption losses of a signal light passing through the optical fiber, at least one optical regenerator, and a network control unit utilizing the optical supervisory channel to communicate with the transmitters, receivers, reconfigurable network node, and regenerator,

wherein the optical regenerator including:

an optical amplifier at an input of the regenerator;

an all-optical nonlinear device to provide a nonlinear transfer function between optical input power of an optical signal after the optical amplifier and optical output power of an optical signal after the nonlinear device;

an adjusting device to receive the optical signal after the nonlinear device, adjust the optical output power of the optical signal after the nonlinear device to a level of launch power from the regenerator, and output an adjusted optical signal;

a first monitoring device including a photodiode to measure the optical input power of the optical signal after the optical amplifier and output a first monitoring signal;

a second monitoring device to monitor an optical signal after the adjusting device and output a second monitoring signal; and

a control unit to receive the first and second monitoring signals, control the optical amplifier based on the first monitoring signal to adjust an optical input power to the nonlinear device to a preset value, control the adjusting device based on the second monitoring signal, and communicate with one of another optical regenerator and a receiver via an optical supervisory channel,

wherein a target value of an average input power to the nonlinear device detected by the photodiode is set as the preset value at a time a new optical path is established in the reconfigurable optical network,

wherein the optical input power to the nonlinear device of each regenerator is adjusted such that a bit error rate at a receiver is minimized and an adjusted value is stored as the target value at the time the new optical path is established,

wherein a procedure of setting the target value is performed in backward direction along the new optical path starting from a regenerator closest to the receiver, and

wherein the optical supervisory channel is used for communication between a location of the receiver and each regenerator.

4. A reconfigurable optical network comprising optical transmitters, optical receivers, at least one optical reconfigurable network node, optical fibers to connect the transmitters with the receivers via the reconfigurable nodes, a plurality of optical amplifiers along the optical fibers to compensate absorption losses of a signal light passing through the optical fiber, at least one optical regenerator, and a network control unit utilizing the optical supervisory channel to communicate with the transmitters, receivers, reconfigurable network node, and regenerator,

wherein the optical regenerator including:

an optical amplifier at an input of the regenerator;

an all-optical nonlinear device to provide a nonlinear transfer function between optical input power of an optical signal after the optical amplifier and optical output power of an optical signal after the nonlinear device;

an adjusting device to receive the optical signal after the nonlinear device, adjust the optical output power of the optical signal after the nonlinear device to a level of launch power from the regenerator, and output an adjusted optical signal;

a first monitoring device including a photodiode to measure the optical input power of the optical signal after the optical amplifier and output a first monitoring signal;

a second monitoring device to monitor an optical signal after the adjusting device and output a second monitoring signal; and

a control unit to receive the first and second monitoring signals, control the optical amplifier based on the first monitoring signal to adjust an optical input power to the nonlinear device to a preset value, control the adjusting device based on the second monitoring signal, and communicate with one of another optical regenerator and a receiver via an optical supervisory channel,

wherein a target value of an average input power to the nonlinear device detected by the photodiode is set as the preset value at a time of installation of the regenerator in the reconfigurable optical network,

wherein the optical input power to the nonlinear device of each regenerator is adjusted such that a bit error rate before a nonlinear device in a subsequent regenerator along an optical path or at a receiver in case of the last regenerator is minimized and an adjusted value is stored as the target value at the time of installation, and

wherein a procedure of setting the target value is performed in forward direction starting from a regenerator closest to a transmitter.

5. A method of controlling an optical regenerator which comprises an all-optical nonlinear device to provide a nonlinear transfer function between optical input power of an optical signal before the nonlinear device and optical output power of an optical signal after the nonlinear device, the method comprising:

amplifying the optical signal before the nonlinear device by an optical amplifier;

monitoring an amplified optical signal between the optical amplifier and the nonlinear device to generate a monitoring signal; and

controlling the optical amplifier based on the monitoring signal,

wherein a target value of the optical input power of the optical signal before the nonlinear device is preset at a time of installation of the regenerator in an optical fiber transmission system, by adjusting the optical input power such that a bit error rate at a receiver in the optical fiber transmission system is minimized and storing an adjusted value as the target value, and

wherein a procedure of setting the target value is performed in backward direction starting from a regenerator closest to the receiver.

6. A method of controlling an optical regenerator which comprises an all-optical nonlinear device to provide a nonlinear transfer function between optical input power of an optical signal before the nonlinear device and optical output power of an optical signal after the nonlinear device, the method comprising:

amplifying the optical signal before the nonlinear device by an optical amplifier;

monitoring an amplified optical signal between the optical amplifier and the nonlinear device to generate a monitoring signal; and

controlling the optical amplifier based on the monitoring signal,

wherein a target value of the optical input power of the optical signal before the nonlinear device is preset at a time of installation of the regenerator in an optical fiber transmission system, by adjusting the optical input power such that a bit error rate before a nonlinear device in a subsequent regenerator or at a receiver in case of the last regenerator in the optical fiber transmission system is minimized and storing an adjusted value as the target value, and

wherein a procedure of setting the target value is performed in forward direction starting from a regenerator closest to a transmitter in the optical fiber transmission system.

7. A method of controlling an optical regenerator which comprises an all-optical nonlinear device to provide a nonlinear transfer function between optical input power of an optical signal before the nonlinear device and optical output power of an optical signal after the nonlinear device, the method comprising:

amplifying the optical signal before the nonlinear device by an optical amplifier;

monitoring an amplified optical signal between the optical amplifier and the nonlinear device to generate a monitoring signal; and

controlling the optical amplifier based on the monitoring signal,

wherein a target value of the optical input power of the optical signal before the nonlinear device is preset at a time a new optical path is established in a reconfigurable optical network, by adjusting the optical input power such that a bit error rate at a receiver in the reconfigurable optical network is minimized and storing an adjusted value as the target value, and

wherein a procedure of setting the target value is performed in backward direction along the new optical path starting from a regenerator closest to the receiver.

8. A method of controlling an optical regenerator which comprises an all-optical nonlinear device to provide a nonlinear transfer function between optical input power of an optical signal before the nonlinear device and optical output power of an optical signal after the nonlinear device, the method comprising:

amplifying the optical signal before the nonlinear device by an optical amplifier;

monitoring an amplified optical signal between the optical amplifier and the nonlinear device to generate a monitoring signal; and

controlling the optical amplifier based on the monitoring signal,

wherein a target value of the optical input power of the optical signal before the nonlinear device is preset at a time of installation of the regenerator in a reconfigurable optical network, by adjusting the optical input power such that a bit error rate before a nonlinear device in a subsequent regenerator along an optical path or at a receiver in case of the last regenerator in the reconfigurable optical network is minimized and storing an adjusted value as the target value, and

wherein a procedure of setting the target value is performed in forward direction starting from a regenerator closest to a transmitter in the reconfigurable optical network.