Optical transmission device and optical signal gain control method

• US 10,530,474 B2
• Filed: 10/09/2018
• Issued: 01/07/2020
• Est. Priority Date: 10/16/2017
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yuki, Masahiro
• Primary Examiner(s): Wolf, Darren E
• Application Number:
  US16/155,823
• Publication Number:
  US 20190115977A1
• Time in Patent Office: 455 Days
• Field of Search: None
• CPC Class Codes: H04B 10/07955 Monitoring or measuring power
• CPC Class Codes: H04B 10/07957 Monitoring or measuring wavelength
• CPC Class Codes: H04B 10/40 Transceivers
• CPC Class Codes: H04B 10/50 Transmitters
• CPC Class Codes: H04B 10/60 Receivers
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0201 Add-and-drop multiplexing
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant

Abstract

An optical transmission device includes an optical amplifier that optically amplifies a wavelength multiplexing signal which is input, a wavelength selective switch that splits, inserts, or transmits an optical signal of any wavelength of the wavelength multiplexing signal, an optical channel power monitor that detects power of each channel of the wavelength multiplexing signal which is input and the wavelength multiplexing signal which is output, and a controller that calculates an amount of change in the optical signal of each channel in which a gain of each channel between an input and an output to and from the device is steady, and adjusts an amount of attenuation of the wavelength selective switch, based on the power of each channel of the wavelength multiplexing signal that is detected by the optical channel power monitor.

Claims

1. An optical transmission device comprising:

a pre-amplifier configured to receive a first wavelength multiplexing signal and optically amplify the first wavelength multiplexing signal which is received;

a pre-wavelength selective switch configured to attenuate each optical signal of the first wavelength multiplexing signal which is amplified by the pre-amplifier and split or transmit each optical signal of any wavelength of the first wavelength multiplexing signal;

a post-wavelength selective switch configured to insert an optical signal and transmit a second wavelength multiplexing signal multiplexed the optical signal which is inserted and the optical signal which is transmitted by the pre-wavelength selective switch and attenuate each optical signal of the second wavelength multiplexing signal;

a post-amplifier configured to receive the second wavelength multiplexing signal and optically amplify the second wavelength multiplexing signal which is received;

an optical channel power monitor configured to detect power of each channel of the first wavelength multiplexing signal and the second wavelength multiplexing signal; and

control circuitry configured to calculate a gain of each channel between the detected power of the each channel of the first wavelength multiplexing signal and the detected power of the each channel of the second wavelength multiplexing signal and adjust an amount of attenuation of the pre-wavelength selective switch or the post-wavelength selective switch based on the gain which is calculated.

2. The optical transmission device according to claim 1,

wherein the control circuitry obtains a difference between the gain of each channel that is detected by the optical channel power monitor and a predetermined target gain and adjusts the amount of attenuation amount of each channel in accordance with the gain of difference.

3. The optical transmission device according to claim 1,

wherein the control circuitry divides an inside of the device into a plurality of blocks in association with a path of the optical signal and adjusts the amount of attenuation of the pre-wavelength selective switch or the post-wavelength selective switch such that the gain between the each channel of the first wavelength multiplexing signal and the each channel of the second wavelength multiplexing signal is a predetermined value.

4. The optical transmission device according to claim 3,

wherein the optical channel power monitor detects power of each channel of the optical signal on the path of the block in which the optical signal is inserted, split, or transmitted, and

wherein the control circuitry adjusts the amount of attenuation of the pre-wavelength selective switch or the post-wavelength selective switch such that the gain of a channel between the first wavelength multiplexing signal and the second wavelength multiplexing signal of the block in which the optical signal is inserted, split or transmitted is a predetermined value.

5. The optical transmission device according to claim 1,

wherein an output power of the pre-amplifier is controlled to be a predetermined value,

wherein the pre-wavelength selective switch is provided at a rear stage of the pre-amplifier and the post-wavelength selective switch is provided at a front stage of the post-amplifier, and

wherein the control circuitry obtains a gain deviation of each channel of the optical signal that is generated by the pre-amplifier or the post-amplifier, and adjusts the amount of attenuation of at least one of the pre-wavelength selective switch and the post-wavelength selective switch such that the gain of each channel between the first wavelength multiplexing signal and the second wavelength multiplexing signal is a predetermined value, based on input and output powers of each channel in an input and an output terminal of the pre-amplifier and an input and output terminal of the post-amplifier.

6. The optical transmission device according to claim 1,

wherein the control circuitry calculates the amount of power change in the optical signal of each channel in which the gain of each channel between the first wavelength multiplexing signal and the second wavelength multiplexing signal is a predetermined value, and adjusts the amount of attenuation of the wavelength selective switch and the gain of the optical amplifier, based on the power of each channel of the first wavelength multiplexing signal and the second wavelength multiplexing signal detected by the optical channel power monitor.

7. The optical transmission device according to claim 6,

wherein the control circuitry adjusts the amount of attenuation of each channel of the pre-wavelength selective switch or the post-wavelength selective switch and the gain of the optical amplifier such that a sum of the amount of attenuation of the pre-wavelength selective switch or the post-wavelength selective switch and an amount of gain change in the optical amplifier becomes a difference between the gain that is detected by the optical channel power monitor and a predetermined target gain.

8. The optical transmission device according to claim 6,

wherein the pre-wavelength selective switch is provided at a rear stage of the pre-amplifier and the post-wavelength selective switch is provided at a front stage of the post-amplifier, and

wherein the control circuitry obtains a gain deviation of each channel that occurs in the pre-amplifier or the post-amplifier, based on power of each channel in an input and output terminal of the pre-amplifier and an input and output terminal of the post-amplifier.

9. The optical transmission device according to claim 1,

wherein the control circuitry adjusts the amount of attenuation of the pre-wavelength selective switch or the post-wavelength selective switch and a gain of the optical amplifier to control an output power of the device of each channel to be a predetermined value, based input and output powers of each channel, and

wherein, after the output power of the device of each channel reaches a target gain range, the control circuitry adjusts the amount of attenuation of the pre-wavelength selective switch or the post-wavelength selective switch and the gain of the pre-amplifier or the post-amplifier to control the gain between the input and the output of each channel of the device to be a predetermined value.

10. An optical signal gain control method of an optical transmission device including a pre-amplifier that receives a first wavelength multiplexing signal and optically amplifies the wavelength multiplexing signal which is received a pre-wavelength selective switch that attenuates each optical signal of the first wavelength multiplexing signal which is amplified by the pre-amplifier and splits or transmits each optical signal of the first wavelength multiplexing signal, a post-wavelength selective switch that inserts an optical signal and transmits a second wavelength multiplexing signal multiplexed the optical signal which is inserted and the optical signal which is transmitted by the pre-wavelength selective switch and attenuates each optical signal of the second wavelength multiplexing signal, a post-amplifier receives the second wavelength multiplexing signal and optically amplify the second wavelength multiplexing signal which is received, an optical channel power monitor that detects power of each channel of the first wavelength multiplexing signal and the second wavelength multiplexing signal, and control circuitry, the method comprising:

causing the control circuitry to calculate a gain of each channel between the detected power of the each channel of the first wavelength multiplexing signal and the detected power of the each channel of the second wavelength multiplexing signal; and

adjusting an amount of attenuation of the pre-wavelength selective switch or the post-wavelength selective switch based on the gain which is calculated.

11. The optical signal gain control method of an optical transmission device according to claim 10,

wherein the control circuitry obtains a difference between a gain of each channel that is detected by the optical channel power monitor and a predetermined target gain and adjusts the amount of attenuation amount of each channel in accordance with the gain of difference.

12. The optical signal gain control method of the optical transmission device according to claim 10,

wherein the control circuitry adjusts the amount of attenuation of each channel of the pre-wavelength selective switch or post-wavelength selective switch and the gain of the pre-amplifier or post-amplifier such that a sum of the amount of attenuation of the pre-wavelength selective switch or post-wavelength selective switch and an amount of gain change in the pre-amplifier or post-amplifier becomes a difference between a gain that is detected by the optical channel power monitor and a predetermined target gain.