Add/drop-drop and continue-module and drop and continue module

• US 7,266,299 B1
• Filed: 08/23/2000
• Issued: 09/04/2007
• Est. Priority Date: 08/23/1999
• Status: Expired due to Fees

• Current Assignee: Nokia Siemens Networks GmbH & Company KG (Nokia Corporation)
• Original Assignee: Siemens AG
• Inventors: Richter, Alexander, Stoll, Detlef, Bock, Harald, Leisching, Patrick
• Primary Examiner(s): Sedighian; M. R.
• Application Number:
  US09/644,881
• Time in Patent Office: 2,568 Days
• Field of Search: 359/124, 359/127, 359/128, 359/130, 359/308, 359/359, 359/563, 359/568, 359/569, 359/572, 385/24, 398/85, 398/84, 398/83, 398/87
• US Class Current: 398/85
• CPC Class Codes: G02B 6/2932 comprising a directional router, e.g. directional coupler, circulator
• CPC Class Codes: G02B 6/29383 Adding and dropping
• CPC Class Codes: G02B 6/29395 configurable, e.g. tunable or reconfigurable switching G02B6/35
• 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 14/0205 Select and combine arrangements, e.g. with an optical combiner at the output after adding or dropping
• CPC Class Codes: H04J 14/0206 Express channels arrangements
• 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]
• CPC Class Codes: H04J 14/0213 Groups of channels or wave bands arrangements
• CPC Class Codes: H04J 14/0219 Modular or upgradable architectures
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0022 using fibre gratings
• CPC Class Codes: H04Q 2011/0035 using miscellaneous components, e.g. circulator, polarisation, acousto/thermo optical

Abstract

A tunable add/drop&continue or drop&continue module comprises two optical filters where at least one is tunable and that are arranged following one another between a branching unit for optical signals and an insertion unit follow a branching unit for optical signals. The reflection attenuation of the one tunable optical filter is lower and the transmission attenuation higher than that of the other optical filter, as a result of which the drop&continue function of the module can be realized without high circuit-oriented expense.

Claims

1. A tunable add/drop-drop and continue module, comprising:

a branching unit for optical signals, wherein each optical signal comprises a plurality of optical transmission channels;

an insertion unit; and

first and second tunable optical filters, arranged in series between the branching unit and insertion unit, wherein the first optical filter has a lower reflection attenuation and a higher transmission attenuation than the second optical filter,

wherein, during the transmission of one of the plurality of transmission channels, the first optical filter is tuned to a pass frequency range that is between two optical transmission channels that neighbor the one transmission channel,

and wherein the pass frequency of the second optical filter is tuned to a frequency range of the one transmission channel, said second optical filter reflecting a portion of the signal in the one transmission channel received from the first optical filter, and passing the remaining portion of the signal in the one transmission channel to effect a drop-and-continue functionality for the channel within the module.

2. The tunable add/drop-drop and continue module according to claim 1, wherein both the first and second optical filters are implemented as band elimination filters.

3. The tunable add/drop-drop and continue module according to claim 1, wherein circulators are provided as the branching unit.

4. The tunable add/drop-drop and continue module according to claim 1, wherein at least one of circulators and optical couplers are provided as the insertion unit.

5. The tunable add/drop-drop and continue module according to claim 1, wherein the first optical filter precedes the second optical filter.

6. The tunable add/drop-drop and continue module according to claim 1, wherein two optical filters for a filter stage and a plurality of the filter stages are connected in series.

7. The tunable add/drop-drop and continue module according to claim 1, wherein both the first and second optical filters are operated in an express mode.

8. The tunable add/drop-drop and continue module according to claim 1, wherein a plurality of series-connected add/drop-drop and continue modules are provided.