OPTICAL BRANCHING UNIT, OPTICAL COMMUNICATION SYSTEM, AND OPTICAL MULTIPLEXING METHOD

• US 20120201543A1
• Filed: 08/23/2010
• Published: 08/09/2012
• Est. Priority Date: 10/16/2009
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Inoue, Takanori
• Granted Patent: US 9,020,353 B2
• Time in Patent Office: Days
• US Class Current: 398/83
• CPC Class Codes: H04B 10/0797 Monitoring line amplifier or line repeater equipment
• CPC Class Codes: H04B 10/291 in which processing or amplification is carried out without conversion of the main signal from optical form
• CPC Class Codes: H04J 14/0201 Add-and-drop multiplexing
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant
• CPC Class Codes: H04J 14/02216 by gain equalization

Abstract

An optical-branching unit enables suppression of deterioration of the transmission characteristic of a survivor signal without executing complex control of constant-power output. Optical-amplification means amplifies and supplies a input optical signal, and when not receiving the optical signal, amplifies and supplies amplified spontaneous emission that the optical-amplification means generates. Detection means detects whether the optical signal is input to the optical-amplification means. When the optical signal is not input to the optical-amplification means, control means sets gain that determines the magnitude of amplification in the optical-amplification means to a predetermined value greater than gain at the time the optical signal is input to the optical-amplification means. Add/drop-multiplexing means receives the output light from the optical-amplification means and other output light and multiplexes an optical signal of a predetermined wavelength in the output light from the optical-amplification means and an optical signal of a specific wavelength in the other output light.

Claims

1. An optical branching unit comprising:

an optical amplification unit means that, when an optical signal is received as input, amplifies and supplies the optical signal, or, when said optical signal is not received as input, amplifies and supplies amplified spontaneous emission that the optical amplification means itself generates;

a detection unit means that detects whether said optical signal is applied as input to said optical amplification unit means;

a control unit means that, when said detection unit means detects that said optical signal is not applied as input to said optical amplification unit means, sets gain that determines the magnitude of amplification in said optical amplification unit means to a predetermined value that is greater than said gain when said optical signal is applied as input to said optical amplification unit means; and

an add/drop multiplexing unit means that receives output light from said optical amplification unit means and other output light and that multiplexes an optical signal of a predetermined wavelength that is contained in the output light from said optical amplification unit means and an optical signal of a designated wavelength that is contained in said other output light.

2. The optical branching unit according to claim 1, wherein said detection unit means detects whether said optical signal is applied as input to said optical amplification unit means by monitoring input to said optical amplification unit means.

3. The optical branching unit according to claim 1, further comprising:

a designated optical amplification unit means that, when a designated optical signal is received as input, amplifies that designated optical signal to supply it as said other output light, or, when said designated optical signal is not received as input, amplifies and supplies amplified spontaneous emission, which said designated optical amplification unit means itself generates, as said other output light;

a designated detection unit means that detects whether said designated optical signal is applied as input to said designated optical amplification unit means; and

a designated control unit means that, when said designated detection unit means detects that said designated optical signal is not applied as input to said designated optical amplification unit means, sets designated gain that determines the magnitude of amplification in said designated optical amplification unit means to a designated value that is greater than said designated gain at the time when said designated optical signal is applied as input to said designated optical amplification unit means.

4. The optical branching unit according to claim 3, wherein said designated detection unit means detects whether said designated optical signal is applied as input to said designated optical amplification unit means by monitoring input to said designated optical amplification unit means.

6. An optical communication system comprising:

the optical branching unit as set forth in claim 1;

a first optical repeater that supplies said optical signal to an optical amplification unit means that is contained in said optical branching unit; and

a second optical repeater that supplies said other output light to an add/drop multiplexing unit means that is contained in said optical branching unit.

7. An optical communication system comprising:

the optical branching unit as set forth in claim 3;

a first optical repeater that supplies said optical signal to an optical amplification unit means that is contained in said optical branching unit; and

a second optical repeater that supplies said designated optical signal to a designated optical amplification unit means that is contained in said optical branching unit.

5. An optical branching unit that incorporates:

an optical amplification unit means that, when an optical signal is received as input, amplifies and supplies that optical signal, or, when said optical signal is not received as input, amplifies and supplies amplified spontaneous emission that said optical amplification unit means itself generates; and

an add/drop multiplexing unit means that receives output light from said optical amplification unit means and other output light, and that multiplexes an optical signal of a predetermined wavelength that is contained in output light from said optical amplification unit means and an optical signal of a designated wavelength that is contained in said other output light.

8. An optical multiplexing method that is an optical multiplexing method in an optical branching unit that includes an optical amplification unit means that, when an optical signal is received as input, amplifies and supplies said optical signal, and when said optical signal is not received as input, amplifies and supplies amplified spontaneous emission that said optical amplification unit means itself generates;

said optical multiplexing method comprising;

detecting whether said optical signal is received as input in said optical amplification unit means;

upon detecting that said optical signal is not received as input in said optical amplification unit means, implementing control to set gain that determines the magnitude of amplification in said optical amplification unit means to a predetermined value that is greater than said gain when said optical signal is received as input in said optical amplification unit means; and

receiving output light from said optical amplification unit means and other output light, and multiplexing an optical signal of a predetermined wavelength that is contained in output light from said optical amplification unit means and an optical signal of a designated wavelength that is contained in said other output light.

9. The optical multiplexing method according to claim 8, wherein said detecting is detecting whether said optical signal is applied as input to said optical amplification unit means by monitoring input to said optical amplification unit means.

10. The optical multiplexing method according to claim 8, wherein:

said optical branching unit includes a designated optical amplification unit means that, when a designated optical signal is received as input, amplifies and supplies said designated optical signal as said other output light, and when said designated optical signal is not received, amplifies and supplies amplified spontaneous emission, which said designated optical amplification unit means itself generates, as said other output light;

further comprising;

detecting whether said designated optical signal is applied as input to said designated optical amplification unit means; and

upon detecting that said designated optical signal is not applied as input to said designated optical amplification unit means, implementing control to set designated gain that determines the magnitude of amplification in said designated optical amplification unit means to a designated value that is greater than said designated gain when said designated optical signal is applied as input to said designated optical amplification unit means.

11. The optical multiplexing method according to claim 10, wherein detecting whether said designated optical signal is applied as input to said designated optical amplification unit means is detecting whether said designated optical signal is applied as input to said designated optical amplification unit means by monitoring input to said designated optical amplification unit means.