Optical add/drop multiplexer

• US 20090297149A1
• Filed: 12/24/2008
• Published: 12/03/2009
• Est. Priority Date: 05/28/2008
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Hanazawa, Hiroyuki, Okuda, Takashi, Nakazato, Hiroaki
• Granted Patent: US 8,098,988 B2
• Time in Patent Office: Days
• US Class Current: 398/79
• CPC Class Codes: G02B 6/2931 Diffractive element operating in reflection
• CPC Class Codes: G02B 6/29313 characterised by means for controlling the position or direction of light incident to or leaving the diffractive element, e.g. for varying the wavelength response switching G02B6/35
• CPC Class Codes: G02B 6/29383 Adding and dropping
• CPC Class Codes: H04J 14/0204 Broadcast and select arrangements, e.g. with an optical splitter at the input before adding or dropping
• CPC Class Codes: H04J 14/0209 Multi-stage arrangements, e.g. by cascading multiplexers or demultiplexers
• CPC Class Codes: H04J 14/021 Reconfigurable arrangements, e.g. reconfigurable optical add/drop multiplexers [ROADM] or tunable optical add/drop multiplexers [TOADM]
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]

Abstract

A disclosed optical add/drop multiplexing device demultiplexes a first signal into multiple signals according to wavelengths, drops one or more of the demultiplexed signals to a transponder, adds one or more signals output from the transponder, multiplexes these signals into a second signal, and outputs it. The device includes an injecting unit for injecting one of measurement signals, each of whose wavelength corresponds to that of a different demultiplexed signal, into a core of a multicore cable within the device, the core being used to transmit the different demultiplexed signal having the corresponding wavelength; a preventing unit for preventing the one measurement signal from emanating; a measuring unit for measuring, for each wavelength, levels of the one measurement signal before and after the corresponding core; a calculating unit for calculating loss of the corresponding core, based on the measured levels; and an informing unit for reporting the calculated loss.

Claims

1. An optical add/drop multiplexing device for demultiplexing a first multiplexed optical signal input via a first optical cable into a plurality of optical signals according to wavelengths, dropping one or more of the demultiplexed optical signals to a transponder, adding one or more optical signals output from the transponder to the demultiplexed optical signals, multiplexing the demultiplexed optical signals into a second multiplexed optical signal, and outputting the second multiplexed optical signal to a second optical cable, the optical add/drop multiplexing device comprising:

an injecting unit configured to inject one of measurement optical signals, each of whose wavelengths corresponds to a wavelength of a different one of the demultiplexed optical signals, into a core of a multicore cable within the optical add/drop multiplexing device, the core being used to transmit one of the demultiplexed optical signals which has the same wavelength as the one of the measurement optical signals;

a preventing unit configured to prevent the one of the measurement optical signals from emanating toward the second optical cable;

a measuring unit configured to measure optical levels of the one of the measurement optical signals at positions before and after the corresponding core of the multiple cable;

a calculating unit configured to calculate, for the wavelength of the one of the measurement optical signals, optical loss of the corresponding core of the multicore cable, based on the measured optical levels; and

an informing unit configured to report the calculated optical loss.

2. The optical add/drop multiplexing device as claimed in claim 1, further comprising a controlling unit configured to control an optical output level of an optical signal output from the transponder based on the calculated optical loss of the corresponding core of the multicore cable in the add direction.

3. The optical add/drop multiplexing device as claimed in claim 1, further comprising a controlling unit configured to control, based on the calculated optical loss of the corresponding core of the multicore cable in the drop direction, an optical output level of the corresponding optical signal output from an opposing optical add/drop multiplexing device which is connected to the optical add/drop multiplexing device by the first optical cable.

4. A within-device optical level measurement method used on an optical add/drop multiplexing device for demultiplexing a first multiplexed optical signal input via a first optical cable into a plurality of optical signals according to wavelengths, dropping one or more of the demultiplexed optical signals to a transponder, adding one or more optical signals output from the transponder to the demultiplexed optimal signals, multiplexing the demultiplexed optical signals into a second multiplexed optical signal, and outputting the second multiplexed optical signal to a second optical cable, the within-device optical level measurement method comprising the steps of:

injecting one of measurement optical signals, each of whose wavelengths corresponds to a wavelength of a different one of the demultiplexed optical signals, into a core of a multicore cable within the optical add/drop multiplexing device, the core being used to transmit one of the demultiplexed optical signals which has the same wavelength as the one of the measurement optical signals;

preventing the one of the measurement optical signals from emanating toward the second optical cable;

measuring optical levels of the one of the measurement optical signals at positions before and after the corresponding core of the multiple cable;

calculating, for the wavelength of the one of the measurement optical signals, optical loss of the corresponding core of the multicore cable, based on the measured optical levels; and

reporting the calculated optical loss.

5. The within-device optical level measurement method as claimed in claim 4, further comprising a step of controlling an optical output level of an optical signal output from the transponder based on the calculated optical loss of the corresponding core of the multicore cable in the add direction.

6. The within-device optical level measurement method as claimed in claim 4, further comprising a step of controlling, based on the calculated optical loss of the corresponding core of the multicore cable in the drop direction, an optical output level of the corresponding optical signal output from an opposing optical add/drop multiplexing device which is connected to the optical add/drop multiplexing device by the first optical cable.