Optical add/drop multiplexer utilizing variable optical attenuator

• US 7,236,704 B1
• Filed: 11/13/2002
• Issued: 06/26/2007
• Est. Priority Date: 11/14/2001
• Status: Expired due to Fees

• Current Assignee: II-VI Incorporated
• Original Assignee: Avanex Corporation (Oclaro (North America), Inc.)
• Inventors: Cao, Simon X. F.
• Primary Examiner(s): Chan; Jason
• Assistant Examiner(s): CURS, NATHAN M
• Application Number:
  US10/294,398
• Time in Patent Office: 1,686 Days
• Field of Search: 398 83- 85
• US Class Current: 398/83
• CPC Class Codes: G02B 6/2931 Diffractive element operating in reflection
• CPC Class Codes: G02B 6/29383 Adding and dropping
• CPC Class Codes: G02B 6/29386 Interleaving or deinterleaving, i.e. separating or mixing subsets of optical signals, e.g. combining even and odd channels into a single optical signal
• CPC Class Codes: G02B 6/4215 the intermediate optical elements being wavelength selective optical elements, e.g. variable wavelength optical modules or wavelength lockers G02B6/4246 takes precedence
• 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 14/0208 Interleaved arrangements
• CPC Class Codes: H04J 14/0209 Multi-stage arrangements, e.g. by cascading multiplexers or demultiplexers
• CPC Class Codes: H04J 14/0213 Groups of channels or wave bands arrangements
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0009 using wavelength filters
• CPC Class Codes: H04Q 2011/0016 using wavelength multiplexing or demultiplexing

Abstract

A switchless optical add/drop module (OADM) includes: a first variable optical splitter (VOS) for splitting a composite optical signal including a plurality of channels into a first portion and a second portion; a first multi-channel variable optical attenuator (MCVOA) optically coupled to the first VOS, where the first MCVOA blocks dropped channels of the first portion, transmits express channels of the first portion, and balances power levels of each of the transmitted express channels of the first portion; a second VOS optically coupled to the first MCVOA opposite to the first VOS for combining the transmitted express channels of the first portion and added channels; and a second MCVOA optically coupled to the first VOS, where the second MCVOA blocks express channels of the second portion, transmits dropped channels of the second portion, and balances power levels of each of the transmitted dropped channels of the second portion.

Claims

1. A switchless optical add/drop module (OADM), comprising:

a first variable optical splitter (VOS) for splitting a composite optical signal comprising a plurality of channels into a first portion and a second portion, wherein the first and second portions each comprise the plurality of channels;

a first multi-channel variable optical attenuator (MCVOA) optically coupled to the first VOS, wherein the first MCVOA blocks dropped channels of the first portion, transmits express channels of the first portion, and balances power levels of each of the transmitted express channels of the first portion;

a second VOS optically coupled to the first MCVOA opposite to the first VOS for combining the transmitted express channels of the first portion and added channels; and

a second MCVOA optically coupled to the first VOS, wherein the second MCVOA blocks express channels of the second portion, transmits dropped channels of the second portion, and balances power levels of each of the transmitted dropped channels of the second portion, wherein the second MCVOA comprises at least one input fiber, a lens optically coupled to the at least one input fiber, a diffraction grating optically coupled to the lens at a side opposite to the at least one input fiber, at least one output fiber optically coupled to the lens at the side opposite to the diffraction grating and a plurality of movable rods residing at the side of the lens opposite to the diffraction grating wherein the plurality of movable rods is capable of intercepting a variable portion of a light traversing through the lens.

2. The OADM of claim 1, wherein the power levels of the transmitted express channels of the first portion are each balanced independently.

3. The OADM of claim 1, wherein the power levels of the transmitted dropped channels of the second portion are each balanced independently.

4. The OADM of claim 1, wherein the second MCVOA further comprises:

at least one detector optically coupled to the lens at the side opposite to the diffraction grating, wherein the plurality of movable rods directs a portion of the intercepted variable portion of the light towards the at least one detector.

5. The OADM of claim 1, wherein the second MCVOA further comprises:

a mirror optically coupled to the lens at the side opposite to the diffraction grating.

6. The OADM of claim 1, further comprising:

an interleaved channel separator optically coupled between the first VOS and the first MCVOA for separating the first portion into a first subset of channels and a second subset of channels, wherein the first subset is received by the first MCVOA, wherein the first MCVOA blocks dropped channels of the first subset, transmits express channels of the first subset, and balances power levels of each of the transmitted express channels of the first subset;

a third MCVOA optically coupled between the interleaved channel separator and the second VOS for receiving the second subset, wherein the third MCVOA blocks dropped channels of the second subset, transmits express channels of the second subset, and balances power levels of each of the transmitted express channels of the second subset; and

an interleaved channel combiner optically coupled to the first and third MCVOA and optically coupled between the first MCVOA and the second VOS for combining the transmitted express channels from the first and third MCVOA.

7. The OADM of claim 1, further comprising:

an interleaved channel separator optically coupled between the first VOS and the second MCVOA for separating the second portion into a first subset of channels and a second subset of channels, wherein the first subset is received by the second MCVOA, wherein the second MCVOA blocks express channels of the first subset, transmits dropped channels of the first subset, and balances power levels of each of the transmitted dropped channels of the first subset;

a third MCVOA optically coupled to the interleaved channel separator for receiving the second subset, wherein the third MCVOA blocks express channels of the second subset, transmits dropped channels of the second subset, and balances power levels of each of the transmitted dropped channels of the second subset; and

an interleaved channel combiner optically coupled to the second and third MCVOA for combining the transmitted dropped channels from the second and third MCVOA.

8. The OADM of claim 1, wherein the second MCVOA comprises a multi-channel variable optical attenuator and demultiplexer (MCVOA-DEMUX), wherein the MCVOA-DEMUX demultiplexes the channels of the second portion, blocks the express channels of the second portion, transmits the dropped channels of the second portion, and balances the power levels of each of the transmitted dropped channels.

9. The OADM of claim 8, further comprising:

a multi-channel variable optical attenuator and multiplexer (MCVOA-MUX) optically coupled to the second VOS, wherein the MCVOA-MUX transmits the added channels, blocks non-added channels, and multiplexes the added channels.

10. A switchless optical add/drop module (OADM), comprising:

a first variable optical splitter (VOS) for splitting a composite optical signal comprising a plurality of channels into a first portion and a second portion, wherein the first and second portions each comprise the plurality of channels;

a first interleaved channel separator optically coupled to the first VOS for separating the first portion into a first subset of channels and a second subset of channels;

a first multi-channel variable optical attenuator (MCVOA) optically coupled to the first interleaved channel separator, wherein the first MCVOA blocks dropped channels of the first subset, transmits express channels of the first subset, and balances power levels of each of the transmitted express channels of the first subset;

a second MCVOA optically coupled to the first interleaved channel separator, wherein the second MCVOA blocks dropped channels of the second subset, transmits express channels of the second subset, and balances power levels of each of the transmitted express channels of the second subset;

a first interleaved channel combiner optically coupled to the first and second MCVOA opposite to the first interleaved channel separator for combining the transmitted express channels from the first and second MCVOA;

a second VOS optically coupled to the interleaved channel combiner for combining the transmitted express channels from the first and second MCVOA and added channels;

a second interleaved channel separator optically coupled to the first VOS for separating the second portion into a third subset of channels and a fourth subset of channels;

a third MCVOA optically coupled to the second interleaved channel separator, wherein the third MCVOA blocks express channels of the third subset, transmits dropped channels of the third subset, and balances power levels of each of the transmitted dropped channels of the third subset;

a fourth MCVOA optically coupled to the second interleaved channel separator, wherein the fourth MCVOA blocks express channels of the fourth subset, transmits dropped channels of the fourth subset, and balances power levels of each of the transmitted dropped channels of the fourth subset; and

a second interleaved channel combiner optically coupled to the third and fourth MCVOA for combining the transmitted dropped channels from the third and fourth MCVOA.

11. A switchless optical add/drop module (OADM), comprising:

a first variable optical splitter (VOS) for splitting a composite optical signal comprising a plurality of channels into a first portion and a second portion, wherein the first and second portions each comprise the plurality of channels;

a first multi-channel variable optical attenuator (MCVOA) optically coupled to the first VOS, wherein the first MCVOA blocks dropped channels of the first portion, transmits express channels of the first portion, and balances power levels of each of the transmitted express channels of the first portion, wherein the first MCVOA comprises at least one input fiber, a lens optically coupled to the at least one input fiber, a diffraction grating optically coupled to the lens at a side opposite to the at least one input fiber, at least one output fiber optically coupled to the lens at the side opposite to the diffraction grating and a plurality of movable rods residing at the side of the lens opposite to the diffraction grating wherein the plurality of movable rods is capable of intercepting a variable portion of a light traversing through the lens,

a second VOS optically coupled to the first MCVOA opposite to the first VOS for combining the transmitted express channels of the first portion and added channels;

a second MCVOA optically coupled to the first VOS, wherein the second MCVOA comprises a multi-channel variable optical attenuator and demultiplexer (MCVOA-DEMUX), wherein the MCVOA-DEMUX demultiplexes the channels of the second portion, blocks express channels of the second portion, transmits dropped channels of the second portion, and balances power levels of each of the transmitted dropped channels; and

a multi-channel variable optical attenuator and multiplexer (MCVOA-MUX) optically coupled to the second VOS, wherein the MCVOA-MUX transmits the added channels, blocks non-added channels, and multiplexes the added channels.

12. A switchless optical add/drop module (OADM), comprising:

a first variable optical splitter (VOS) for splitting a composite optical signal comprising a plurality of channels into a first portion and a second portion, wherein the first and second portions each comprise the plurality of channels;

a first interleaved channel separator optically coupled to the first VOS for separating the first portion into a first subset of channels and a second subset of channels;

a first multi-channel variable optical attenuator (MCVOA) optically coupled to the first interleaved channel separator, wherein the first MCVOA blocks dropped channels of the first subset, transmits express channels of the first subset, and balances power levels of each of the transmitted express channels of the first subset;

a second MCVOA optically coupled to the first interleaved channel separator, wherein the second MCVOA blocks dropped channels of the second subset, transmits express channels of the second subset, and balances power levels of each of the transmitted express channels of the second subset;

a first interleaved channel combiner optically coupled to the first and second MCVOA opposite to the first interleaved channel separator for combining the transmitted express channels from the first and second MCVOA;

a second VOS optically coupled to the interleaved channel combiner for combining the transmitted express channels from the first and second MCVOA and added channels;

a second interleaved channel separator optically coupled to the first VOS for separating the second portion into a third subset of channels and a fourth subset of channels;

a first multi-channel variable optical attenuator and demultiplexer (MCVOA-DEMUX) optically coupled to the second interleaved channels separator, wherein the first MCVOA-DEMUX demultiplexes the channels of the third subset, blocks express channels of the third subset, transmits dropped channels of the third subset, and balances power levels of each of the transmitted dropped channels of the third subset;

a second MCVOA-DEMUX optically coupled to the second interleaved channel separator, wherein the second MCVOA-DEMUX demultiplexes the channels of the fourth subset, blocks express channels of the fourth subset, transmits dropped channels of the fourth subset, and balances power levels of each of the transmitted dropped channels of the fourth subset;

a first multi-channel variable optical attenuator and multiplexer (MCVOA-MUX) optically coupled to the second VOS, wherein the first MCVOA-MUX receives a fifth subset of channels, blocks non-added channels of the fifth subset, transmits added channels of the fifth subset, balances power levels of each of the transmitted added channels of the fifth subset, and multiplexes the transmitted added channels of the fifth subset;

a second MCVOA-MUX optically coupled to the second VOS, wherein the second MCVOA-MUX receives a sixth subset of channels, blocks non-added channels of the sixth subset, transmits added channels of the sixth subset, balances power levels of each of the transmitted added channels of the sixth subset, and multiplexes the transmitted added channels of the sixth subset; and

a second interleaved channel combiner optically coupled to the first and second MCVOA-MUX and between the first MCVOA-MUX and the second VOS for combining the multiplexed transmitted added channels from the first and second MCVOA-MUX.

13. A system, comprising:

an input fiber;

an output fiber;

a switchless optical add/drop module (OADM) coupled to the input and output fibers, wherein the switchless OADM comprises;

a first variable optical splitter (VOS) for splitting a composite optical signal comprising a plurality of channels into a first portion and a second portion, wherein the first and second portions each comprise the plurality of channels,

a first multi-channel variable optical attenuator (MCVOA) optically coupled to the first VOS, wherein the first MCVOA blocks dropped channels of the first portion, transmits express channels of the first portion, and balances power levels of each of the transmitted express channels of the first portion, wherein the first MCVOA comprises at least one input fiber, a lens optically coupled to the at least one input fiber, a diffraction grating optically coupled to the lens at a side opposite to the at least one input fiber, at least one output fiber optically coupled to the lens at the side opposite to the diffraction grating and a plurality of movable rods residing at the side of the lens opposite to the diffraction grating, wherein the plurality of movable rods is capable of intercepting a variable portion of a light traversing through the lens,

a second VOS optically coupled to the first MCVOA opposite to the first VOA for combining the transmitted express channels of the first portion and added channels, and

a second MCVOA optically coupled to the first VOS, wherein the second MCVOA blocks express channels of the second portion, transmits dropped channels of the second portion, and balances power levels of each of the transmitted dropped channels of the second portion;

an optical amplifier optically coupled to the output fiber;

an add line optically coupled to the switchless OADM; and

a drop line optically coupled to the switchless OADM.

14. The system of claim 13, further comprising:

an analyzer/controller module optically coupled to the output fiber, the add line, and the drop line and electrically coupled to the optical amplifier and the switchless OADM.

15. The system of claim 14, further comprising:

a first optical tap downstream from the optical amplifier optically coupled between the output fiber and the analyzer/controller module;

a second optical tap optically coupled between the add line and the analyzer/controller module; and

a third optical tap optically coupled between the drop line and the analyzer/controller module.

16. The system of claim 14, further comprising:

a second optical amplifier optically coupled to the drop line.

17. The system of claim 16, further comprising:

a first set of optical taps upstream and downstream from the optical amplifier optically coupled between the output fiber and the analyzer/controller module;

a second set of optical taps optically coupled between the add line and the analyzer/controller module; and

a third set of optical taps upstream and downstream from the second optical amplifier optically coupled between the drop line and the analyzer/controller module.

18. A system, comprising:

an input fiber;

an output fiber;

a switchless optical add/drop module (OADM) coupled to the input and output fibers, wherein the switchless OADM comprises;

a first variable optical splitter (VOS) for splitting a composite optical signal comprising a plurality of channels into a first portion and a second portion, wherein the first and second portions each comprise the plurality of channels,

a first multi-channel variable optical attenuator (MCVOA) optically coupled to the first VOS, wherein the first MCVOA blocks dropped channels of the first portion, transmits express channels of the first portion, and balances power levels of each of the transmitted express channels of the first portion,

a second VOS optically coupled to the first MCVOA opposite to the first VOA for combining the transmitted express channels of the first portion and added channels, and

a second MCVOA optically coupled to the first VOS, wherein the second MCVOA blocks express channels of the second portion, transmits dropped channels of the second portion, and balances power levels of each of the transmitted dropped channels of the second portion;

an optical amplifier optically coupled to the output fiber;

an add line optically coupled to the switchless OADM;

a drop line optically coupled to the switchless OADM;

an analyzer/controller module optically coupled to the output fiber, the add line, and the drop line and electrically coupled to the optical amplifier and the switchless OADM;

a first optical tap downstream from the optical amplifier optically coupled between the output fiber and the analyzer/controller module;

a second optical tap optically coupled between the add line and the analyzer/controller module; and

a third optical tap optically coupled between the drop line and the analyzer/controller module.

19. A system, comprising:

an input fiber;

an output fiber;

a switchless optical add/drop module (OADM) coupled to the input and output fibers, wherein the switchless OADM comprises;

a first variable optical splitter (VOS) for splitting a composite optical signal comprising a plurality of channels into a first portion and a second portion, wherein the first and second portions each comprise the plurality of channels,

a first multi-channel variable optical attenuator (MCVOA) optically coupled to the first VOS, wherein the first MCVOA blocks dropped channels of the first portion, transmits express channels of the first portion, and balances power levels of each of the transmitted express channels of the first portion,

a second VOS optically coupled to the first MCVOA opposite to the first VOA for combining the transmitted express channels of the first portion and added channels, and

a second MCVOA optically coupled to the first VOS, wherein the second MCVOA blocks express channels of the second portion, transmits dropped channels of the second portion, and balances power levels of each of the transmitted dropped channels of the second portion;

an optical amplifier optically coupled to the output fiber;

an add line optically coupled to the switchless OADM;

a drop line optically coupled to the switchless OADM;

an analyzer/controller module optically coupled to the output fiber, the add line, and the drop line and electrically coupled to the optical amplifier and the switchless OADM;

a second optical amplifier optically coupled to the drop line;

a first set of optical taps upstream and downstream from the optical amplifier optically coupled between the output fiber and the analyzer/controller module;

a second set of optical taps optically coupled between the add line and the analyzer/controller module; and

a third set of optical taps upstream and downstream from the second optical amplifier optically coupled between the drop line and the analyzer/controller module.

20. A switchless optical add/drop module (OADM), comprising:

a first variable optical splitter (VOS) for splitting a composite optical signal comprising a plurality of channels into a first portion and a second portion, wherein the first and second portions each comprise the plurality of channels;

a first multi-channel variable optical attenuator (MCVOA) optically coupled to the first VOS, wherein the first MCVOA blocks dropped channels of the first portion, transmits express channels of the first portion, and balances power levels of each of the transmitted express channels of the first portion, wherein the first MCVOA comprises;

at least one input fiber;

a lens optically coupled to the at least one input fiber;

a diffraction grating optically coupled to the lens at a side opposite to the at least one input fiber;

at least one output fiber optically coupled to the lens at the side opposite to the diffraction grating; and

a plurality of movable rods residing at the side of the lens opposite to the diffraction grating, wherein the plurality of movable rods is capable of intercepting a variable portion of a light traversing through the lens;

a second VOS optically coupled to the first MCVOA opposite to the first VOS for combining the transmitted express channels of the first portion and added channels; and

a second MCVOA optically coupled to the first VOS, wherein the second MCVOA blocks express channels of the second portion, transmits dropped channels of the second portion, and balances power levels of each of the transmitted dropped channels of the second portion.

21. The OADM of claim 20, wherein the first MCVOA further comprises:

at least one detector optically coupled to the lens at the side opposite to the diffraction grating, wherein the plurality of movable rods directs a portion of the intercepted variable portion of the light towards the at least one detector.

22. The OADM of claim 21, wherein the first MCVOA further comprises:

a mirror optically coupled to the lens at the side opposite to the diffraction grating.

23. A switchless optical add/drop module (OADM), comprising:

a first variable optical splitter (VOS) for splitting a composite optical signal comprising a plurality of channels into a first portion and a second portion, wherein the first and second portions each comprise the plurality of channels;

a first multi-channel variable optical attenuator (MCVOA) optically coupled to the first VOS, wherein the first MCVOA blocks dropped channels of the first portion, transmits express channels of the first portion, and balances power levels of each of the transmitted express channels of the first portion;

a second VOS optically coupled to the first MCVOA opposite to the first VOS for combining the transmitted express channels of the first portion and added channels;

a second MCVOA optically coupled to the first VOS, wherein the second MCVOA blocks express channels of the second portion, transmits dropped channels of the second portion, and balances power levels of each of the transmitted dropped channels of the second portion;

a first interleaved channel separator optically coupled between the first VOS and the first MCVOA for separating the first portion into a first subset of channels and a second subset of channels, wherein the first subset is received by the first MCVOA, wherein the first MCVOA blocks dropped channels of the first subset, transmits express channels of the first subset, and balances power levels of each of the transmitted express channels of the first subset;

a third MCVOA optically coupled between the first interleaved channel separator and the second VOA for receiving the second subset, wherein the third MCVOA blocks dropped channels of the second subset, transmits express channels of the second subset, and balances power levels of each of the transmitted express channels of the second subset;

a first interleaved channel combiner optically coupled to the first and third MCVOA and optically coupled between the first MCVOA and the second YOS for combining the transmitted express channels from the first and third MCVOA;

a second interleaved channel separator optically coupled between the first VOS and the second MCVOA for separating the second portion into a third subset of channels and a fourth subset of channels, wherein the third subset is received by the second MCVOA, wherein the second MCVOA comprises a first MCVOA-DEMUX, wherein the first MCVOA-DEMUX demultiplexes the channels of the third subset, blocks express channels of the third subset, transmits dropped channels of the third subset, and balances power levels of each of the transmitted dropped channels of the third subset; and

a second MCVOA-DEMUX optically coupled to the second interleaved channels separator for receiving the fourth subset, wherein the second MCVOA-DEMUX demultiplexes the channels of the fourth subset, blocks express channels of the fourth subset, transmits dropped channels of the fourth subset, and balances power levels of each of the transmitted dropped channels of the fourth subset.

24. The OADM of claim 23, further comprising:

a first MCVOA-MUX optically coupled to the second YOS, wherein the first MCVOA-MUX receives a fifth subset of channels, blocks non-added channels of the fifth subset, transmits added channels of the fifth subset, balances power levels of each of the transmitted added channels of the fifth subset, and multiplexes the transmitted added channels of the fifth subset;

a second MCVOA-MUX optically coupled to the second VOS, wherein the second MCVOA-MUX receives a sixth subset of channels, blocks non-added channels of the sixth subset, transmits added channels of the sixth subset, balances power levels of each of the transmitted added channels of the sixth subset, and multiplexes the transmitted added channels of the sixth subset; and

a second interleaved channel combiner optically coupled to the first and second MCVOA-MUX and between the first MCVOA-MUX and the second VOS for combining the multiplexed transmitted added channels from the first and second MCVOA-MUX.