Optical processing

• US 9,529,325 B2
• Filed: 12/12/2014
• Issued: 12/27/2016
• Est. Priority Date: 09/03/2001
• Status: Expired due to Term

• Current Assignee: Thomas Swan & Company Limited (Aixtron AG)
• Original Assignee: Thomas Swan & Company Limited (Aixtron AG)
• Inventors: Holmes, Melanie
• Primary Examiner(s): Ben, Loha
• Application Number:
  US14/568,750
• Publication Number:
  US 20150177685A1
• Time in Patent Office: 746 Days
• Field of Search: 359237-239, 359/279, 359/555, 359/556, 359/558, 359/3, 359/9, 359/11, 359/24, 359/29, 398/43, 398/45, 398/48, 398/49, 398/81, 398/84, 385/18, 385/37, 385/119, 385/132, 385/133, 385/146, 385/147
• US Class Current: 1/1
• CPC Class Codes: G02B 26/06 for controlling the phase of light G02B26/08 takes precedence , measuring optical phase difference G01J9/00
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02B 6/266 the optical element being an attenuator
• CPC Class Codes: G02B 6/29311 Diffractive element operating in transmission
• CPC Class Codes: G02B 6/29314 by moving or modifying the diffractive element, e.g. deforming
• CPC Class Codes: G02B 6/2938 for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
• CPC Class Codes: G02B 6/29391 Power equalisation of different channels, e.g. power flattening
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/3534 the optical element being diffractive, i.e. a grating
• CPC Class Codes: G02B 6/3548 1xN switch, i.e. one input and a selectable single output of N possible outputs
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02F 1/1326 Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides
• CPC Class Codes: G02F 1/13342 Holographic polymer dispersed liquid crystals
• CPC Class Codes: G02F 1/1335 Structural association of cells with optical devices, e.g. polarisers or reflectors
• CPC Class Codes: G02F 1/29 for the control of the position or the direction of light beams, i.e. deflection
• CPC Class Codes: G02F 1/291 Two-dimensional analogue deflection
• CPC Class Codes: G02F 1/31 Digital deflection, i.e. optical switchingG02F1/33 takes precedence
• CPC Class Codes: G02F 1/3132 of directional coupler type
• CPC Class Codes: G02F 2201/30 : grating
• CPC Class Codes: G02F 2201/34 : reflector
• CPC Class Codes: G02F 2203/12 : spatial light modulator
• CPC Class Codes: G02F 2203/28 : focussing or defocussing
• CPC Class Codes: G02F 2203/50 : Phase-only modulation
• CPC Class Codes: G03H 1/0005 : Adaptation of holography to specific applications holographic optical element G02B5/32; holographic scanner G02B26/106; recognition using holographic mask G06V10/88; holographic memories G11B7/0065, G11C13/042
• CPC Class Codes: G03H 1/02 : Details of features involved during the holographic process; Replication of holograms without interference recording
• CPC Class Codes: G03H 1/04 : Processes or apparatus for producing holograms G03H1/26 takes precedence
• CPC Class Codes: G03H 1/08 : Synthesising holograms, i.e. holograms synthesized from objects or objects from hologramsusing electric digital computers G06F; G06T
• CPC Class Codes: G03H 1/0866 : Digital holographic imaging, i.e. synthesizing holobjects from holograms
• CPC Class Codes: G03H 1/0891 : Processes or apparatus adapted to convert digital holographic data into a hologram G03H1/2294 takes precedence
• CPC Class Codes: G03H 1/2286 : Particular reconstruction light G03H1/24 takes precedence; Beam properties
• CPC Class Codes: G03H 1/2294 : Addressing the hologram to an active spatial light modulator
• CPC Class Codes: G03H 1/26 : Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
• CPC Class Codes: G03H 2001/0224 : Active addressable light modulator, i.e. Spatial Light Modulator [SLM]
• CPC Class Codes: G03H 2001/0491 : by monitoring the hologram formation, e.g. via a feed-back loop
• CPC Class Codes: G03H 2001/261 : in optical contact
• CPC Class Codes: G03H 2001/264 : One hologram being a HOE
• CPC Class Codes: G03H 2222/13 : Multi-wavelengths wave with discontinuous wavelength ranges G03H2222/18 takes precedence
• CPC Class Codes: G03H 2222/32 : Unpolarised light
• CPC Class Codes: G03H 2223/23 : Diffractive element
• CPC Class Codes: G03H 2225/32 : Phase only
• CPC Class Codes: G03H 2225/52 : Reflective modulator
• CPC Class Codes: G03H 2225/60 : Multiple SLMs
• CPC Class Codes: G03H 2226/02 : Computing or processing means, e.g. digital signal processor [DSP]
• 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 14/0217 : Multi-degree architectures, e.g. having a connection degree greater than two
• CPC Class Codes: H04J 14/0219 : Modular or upgradable architectures
• CPC Class Codes: H04J 14/022 : For interconnection of WDM optical networks
• CPC Class Codes: H04J 14/08 : Time-division multiplex systems
• CPC Class Codes: H04Q 11/0005 : Switch and router aspects
• CPC Class Codes: H04Q 2011/0016 : using wavelength multiplexing or demultiplexing
• CPC Class Codes: H04Q 2011/0028 : using holograms
• CPC Class Codes: H04Q 2011/0039 : Electrical control

Abstract

A modular routing node includes a single input port and a plurality of output ports. The modular routing node is arranged to produce a plurality of different deflections and uses small adjustments to compensate for wavelength differences and alignment tolerances in an optical system. An optical device is arranged to receive a multiplex of many optical signals at different wavelengths, to separate the optical signals into at least two groups, and to process at least one of the groups adaptively.

Claims

1. An optical processor for selectively routing optical signals on wavelength channels from at least one input port to at least two output ports, the optical processor comprising:

a reflective spatial light modulator (“

SLM”

) having a two-dimensional array of

controllable elements, wherein the SLM is configured for selection of the controllable elements whereby two-dimensional groups of controllable elements are formed at chosen locations of the SLM to independently and controllably deflect light incident on the two-dimensional groups of controllable elements;

a dispersion device positioned to receive an input beam from each of the at least one input port and disperse light from the input beam;

a focusing device disposed between the reflective SLM and the dispersion device to receive the dispersed light from the dispersion device and spatially distribute this dispersed light by wavelength across the SLM and within each of the two-dimensional groups; and

a controller coupled to the reflective SLM for assigning which controllable elements correspond to which group and configurable to select the groups so that each wavelength channel from the at least one input port corresponds to a respective one of the groups and further configurable to select a first set of one or more of the optical signals for routing to a first one of the output ports and to further select a second set of one or more of the optical signals for routing to a second one of the output ports,

wherein, during operation, the controller causes the reflective SLM to deflect the first and second sets of one or more of the optical signals incident on the SLM back to the focusing device, wherein the deflections provided by the controllable elements of the groups are selected by the controller so that the focusing device then directs the first and second sets of one or more optical signals to different respective locations on the dispersion device, and wherein the dispersion device combines the wavelength channels from the first set of one or more optical signals into a first output beam and combines the wavelength channels from the second set of one or more optical signals into a second output beam.

2. The optical processor of claim 1, wherein the dispersion device, focusing device, and SLM are arranged so that different wavelength channels from a common input beam that have a common deflection caused by the SLM are combined into a common output beam by the dispersion device upon returning to the dispersion device from the focusing device.

3. The optical processor of claim 1, wherein the input beam comprises optical signals on at least three wavelength channels and wherein the optical processor is configurable to select the first set of one or more of the optical signals to include the signals on a first and a second of the three wavelength channels and to further select the second set of one or more of the optical signals to include the signal on a third of the three wavelength channels.

4. The optical processor of claim 1, wherein the at least one input port comprises at least two input ports, and wherein the dispersion device, focusing device, and SLM are arranged so that the controller can cause the SLM to independently deflect light incident on the groups so that selected wavelength channels from different input beams are combined into a common output beam by the dispersion device upon returning to the dispersion device from the focusing device.

5. The optical processor of claim 1, wherein the at least one input port comprises at least first and second input ports, wherein the input beam corresponding to the first input port comprises an optical signal on a first wavelength channel and the input beam corresponding to the second input port comprises an optical signal on the same first wavelength channel and another optical signal on a second wavelength channel, and wherein the optical processor is configurable to select the first set of one or more optical signals to include the signal on the first wavelength channel from the first input port and the signal on the second wavelength channel from the second input port and to further select the second set of one or more optical signals to include the signal on the first wavelength channel from the second input port.

6. The optical processor of claim 1, wherein the at least one input port comprises at least two input ports and wherein the input beams incident on the dispersion device are spatially separated from one another.

7. The optical processor of claim 1, wherein the output beams exiting the dispersion device are spatially separated from one another.

8. The optical processor of claim 1, wherein the focusing device focuses the dispersed light for each wavelength channel onto the corresponding group of controllable elements.

9. The optical processor of claim 8, wherein each group of controllable elements defines a width on the SLM in at least one dimension of between 10 and 50 pixels.

10. The optical processor of claim 1, wherein the two-dimensional array of controllable elements is a two-dimensional array of controllable phase-modulating elements.

11. The optical processor of claim 10, wherein the controller is configurable to cause the SLM to display multiple holograms on the corresponding groups of controllable elements to independently and controllably deflect light incident on the corresponding groups of controllable elements.

12. The optical processor of claim 11, wherein the SLM is an LCOS SLM.

13. The optical processor of claim 11, wherein the controller is configurable to control stitching errors between adjacent holograms providing the same deflection.

14. The optical processor of claim 13, wherein the controller is configured to minimize stitching errors between adjacent holograms providing the same deflection.

15. The optical processor of claim 14, wherein the stitching errors are minimized to achieve uniform transmission across at least one of the adjacent wavelength channels.

16. The optical processor of claim 13, wherein the stitching errors are controlled by translating one of the adjacent holograms relative to the other adjacent hologram.

17. The optical processor of claim 16, wherein the adjacent holograms are translated relative to one another in a direction orthogonal to the wavelength dispersion.

18. The optical processor of claim 11, wherein the controller is configurable to adjust a transmission spectrum between adjacent channels directed to a common output beam.

19. The optical processor of claim 18, wherein the controller is configurable to adjust the transmission spectrum between adjacent channels directed to the common output beam to reduce a notch in the transmission spectrum.

20. The optical processor of claim 19, wherein the controller is configurable to adjust the transmission spectrum between adjacent channels directed to the common output beam to reduce the notch by minimizing stitching errors between adjacent holograms providing the same deflection.

21. The optical processor of claim 1, wherein the controller is configured to reassign which controllable elements are assigned to each group of controllable elements in response to a request from a network management system.

22. The optical processor of claim 1, wherein the controller is configured to reassign which controllable elements are assigned to each group of controllable elements in response to a change in central wavelength of one or more of the wavelength channels or a change in bandwidth of one or more of the wavelength channels or both.

23. The optical processor of claim 1, wherein the controller is configured to control filtering effects between wavelength channels corresponding to adjacent groups of controllable elements on the SLM.

24. The optical processor of claim 1, wherein during operation the controller causes the reflective SLM to deflect the first and second sets of one or more optical signals incident on the SLM directly back to the focusing device.

25. The optical processor of claim 1, wherein during a routing operation the first and second sets of one or more optical signals deflect from the SLM only once.

26. The optical processor of claim 1, wherein the at least one input port comprises multiple input ports, and wherein all of the optical signals from the multiple input ports on a common channel see the same group of controllable elements.

27. The optical processor of claim 1, wherein, during operation, the output beams exiting the dispersion device are parallel to one another.

28. The optical processor of claim 27, wherein, during operation, the input beam is incident on the dispersion device anti-parallel to the output beams exiting the dispersion device.

29. The optical processor of claim 1, wherein the deflections provided by the controllable elements of the SLM are reconfigurable as a function of time.

30. The optical processor of claim 1, wherein the controller is configured to select the groups of controllable elements so that groups corresponding to at least one pair of adjacent wavelength channels are spaced from one another on the SLM.

31. The optical processor of claim 30, wherein the controller is configured to cause the controllable elements in the space between the groups corresponding to the at least one pair of adjacent wavelength channels to form guard bands.

32. The optical processor of claim 31 wherein the controller causes the controllable elements forming the guard bands to deflect incident light away from the at least two output ports.

33. The optical processor of claim 1, wherein, during operation, the controller is configured to select a third set of the optical signals and causes the controllable elements to block the third set of the optical signals from reaching the output ports.

34. The optical processor of claim 33, wherein the optical processor comprises an optical absorber and wherein the controller causes the controllable elements to block the third set of the optical signals by directing the third set of the optical signals to the optical absorber.

35. The optical processor of claim 33, wherein the controller causes the controllable elements to block the third set of the optical signals by directing the third set of the optical signals to be offset from the multiple output ports in a direction orthogonal to a one-dimensional array formed by the multiple output ports.

36. The optical processor of claim 1, wherein for at least one of the groups of controllable elements, at least some of the deflections selected by the controller differ from one another.

37. The optical processor of claim 36, wherein the controller selects the deflections to differ from one another to shape an incident beam for at least one optical signal in the first set of one or more optical signals.

38. The optical processor of claim 37, wherein the controller selects the deflections to differ from one another to vary a degree to which the incident beam for the at least one optical signal in the first set of one or more optical signals couples into an output fiber for an output port corresponding to the first output beam.

39. The optical processor of claim 1, wherein the controller is configurable to select the groups so that at least one group has a size different from that of another group or at least one group has a shape different from that of another group.

40. The optical processor of claim 1, wherein the controller is configured to change one or more of sizes, shapes, and positions of the groups in response to a change in central wavelength or a change in a bandwidth or both of one or more of the wavelength channels.

41. The optical processor of claim 40, wherein the controller is configured to change two or more of the sizes, shapes, and positions of the groups in response to a change in central wavelength or a change in a bandwidth or both of one or more of the wavelength channels.

42. The optical processor of claim 1, wherein the controller is configured to change one or more of sizes, shapes, and positions of the groups in response to a request from a network management system.

43. The optical processor of claim 42, wherein the controller is configured to change two or more of the sizes, shapes, and positions of the groups in response to a request from the network management system.

44. An optical processor for selectively routing optical signals on wavelength channels from multiple input ports to at least one output port, the optical processor comprising:

a reflective spatial light modulator (“

SLM”

) having a two-dimensional array of controllable elements, wherein the SLM is configured for selection of the controllable elements whereby two-dimensional groups of controllable elements are formed at chosen locations of the SLM to independently and controllably deflect light incident on the two-dimensional groups of controllable elements;

a dispersion device positioned to receive an input beam from each of the multiple input ports and disperse light from the input beams;

a focusing device disposed between the reflective SLM and the dispersion device to receive the dispersed light from the dispersion device and spatially distribute this dispersed light by wavelength across the SLM and within each of the two-dimensional groups; and

a controller coupled to the reflective SLM for assigning which controllable elements correspond to which group and configurable to select the groups so that each set of optical signals from different input ports on the same wavelength channel corresponds to a respective one of the groups and further configurable to select a first subset of the optical signals for routing to a first one of the at least one output port, wherein the first subset includes optical signals from different input ports,

wherein, during operation, the controller causes the reflective SLM to deflect the first subset of optical signals incident on the SLM back to the focusing device, wherein the deflections provided by the controllable elements of the groups are selected by the controller so that the focusing device then directs the first subset of optical signals to a common location on the dispersion device, and wherein the dispersion device combines the wavelength channels from the first subset of optical signals into a first output beam, and

wherein the dispersion device, focusing device, and SLM are arranged so that the controller can cause the SLM to independently deflect light incident on the groups so that different wavelength channels from different input beams are combined into a common output beam by the dispersion device upon returning to the dispersion device from the focusing device.

45. The optical processor of claim 44, wherein the input beam corresponding to a first one of the input ports comprises an optical signal on a first wavelength channel and the input beam corresponding to a second one of the input ports comprises an optical signal on the same first wavelength channel and another optical signal on a second wavelength channel, and wherein the optical processor is configurable to select the first subset of the optical signals to include the signal on the first wavelength channel from the first input port and the signal on the second wavelength channel from the second input port.

46. The optical processor of claim 44, wherein, during operation, the controller is configured to select a second subset of the optical signals and causes the controllable elements to block the second subset of the optical signals from reaching the at least one output port.

47. The optical processor of claim 46, wherein the optical processor comprises an optical absorber and wherein the controller causes the controllable elements to block the second subset of the optical signals by directing the second subset of the optical signals to the optical absorber.

48. The optical processor of claim 46, wherein the controller causes the controllable elements to block the second subset of the optical signals by directing the second subset of the optical signals to be offset from the at least one output port in a direction orthogonal to a one-dimensional array formed by the multiple input ports.

49. An optical processor for selectively routing optical signals on wavelength channels from one or more input ports to one or more output ports, the optical processor comprising:

a reflective spatial light modulator (“

SLM”

) having a two-dimensional array of controllable elements, wherein the SLM is configured for selection of the controllable elements whereby two-dimensional groups of controllable elements are formed at chosen locations of the SLM to independently and controllably deflect light incident on the two-dimensional groups of controllable elements;

a dispersion device positioned to receive an input beam from each of the one or more input ports and disperse light from the input beam;

a focusing device disposed between the reflective SLM and the dispersion device to receive the dispersed light from the dispersion device and spatially distribute this dispersed light by wavelength across the SLM and within each of the two-dimensional groups; and

a controller coupled to the reflective SLM for assigning which controllable elements correspond to which group and configurable to select the groups so that each wavelength channel from the one or more input ports corresponds to one of the groups and further configurable to select a first subset of one or more of the optical signals for routing to a first one of the one or more output ports,

wherein the two-dimensional array of controllable elements is a two-dimensional array of controllable phase-modulating elements and wherein the controller is configurable to cause the SLM to display multiple holograms on the corresponding groups of controllable elements to independently and controllably deflect light incident on the corresponding groups of controllable elements, and

wherein the controller is configurable to adjust a transmission spectrum between optical signals on adjacent wavelength channels.

50. The optical processor of claim 49, wherein the controller is configurable to adjust the transmission spectrum between adjacent channels directed to a common output port to reduce a notch in the transmission spectrum.

51. The optical processor of claim 50, wherein the controller is configurable to adjust the transmission spectrum between adjacent channels directed to the common output port to reduce the notch by minimizing stitching errors between adjacent holograms providing the same deflection.

52. The optical processor of claim 49, wherein the controller is configurable to adjust the transmission spectrum between the optical signals on the adjacent wavelength channels by controlling stitching errors between adjacent holograms providing the same deflection.

53. The optical processor of claim 52 wherein the controller is configured to minimize stitching errors between adjacent holograms providing the same deflection.

54. The optical processor of claim 53, wherein the stitching error is minimized to achieve uniform transmission across at least one of the adjacent wavelength channels.

55. The optical processor of claim 54, wherein the stitching errors are controlled by translating one of the adjacent holograms relative to the other adjacent hologram.

56. The optical processor of claim 55, wherein the adjacent holograms are translated relative to one another in a direction orthogonal to the wavelength dispersion.

57. The optical processor of claim 49, wherein the controller is configured to select the groups of controllable elements so that groups corresponding to the adjacent wavelength channels are spaced from one another on the SLM.

58. The optical processor of claim 57, wherein the controller is configured to cause the controllable elements in the space between the groups corresponding to the adjacent wavelength channels to form a guard band.

59. The optical processor of claim 58, wherein the controller causes the controllable elements forming the guard band to deflect incident light away from the one or more output ports.