Optical branching unit, optical communication system, and optical multiplexing method

• US 9,020,353 B2
• Filed: 08/23/2010
• Issued: 04/28/2015
• Est. Priority Date: 10/16/2009
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Inoue, Takanori
• Primary Examiner(s): Vanderpuye, Ken
• Assistant Examiner(s): SANCHEZ, DIBSON J
• Application Number:
  US13/502,058
• Publication Number:
  US 20120201543A1
• Time in Patent Office: 1,709 Days
• Field of Search: 398104-105, 398/37, 398/160, 398173-181, 398/43, 398 79- 83, 359333-359
• 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 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 unit itself generates;

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

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

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

a designated optical amplification unit 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 itself generates, as said other output light;

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

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

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

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

4. 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 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 that is contained in said optical branching unit.

5. An optical multiplexing method that is an optical multiplexing method in an optical branching unit that includes an optical amplification unit 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 itself generates said optical multiplexing method comprising:

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

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

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

wherein said optical branching unit includes a designated optical amplification unit 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 itself generates, as said other output light, and

wherein the optical multiplexing method further comprises;

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

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

6. The optical multiplexing method according to claim 5, wherein said detecting is detecting whether said optical signal is applied as input to said optical amplification unit by monitoring input to said optical amplification unit.

7. The optical multiplexing method according to claim 5, wherein detecting whether said designated optical signal is applied as input to said designated optical amplification unit is detecting whether said designated optical signal is applied as input to said designated optical amplification unit by monitoring input to said designated optical amplification unit.