Optical processing

• US 8,089,683 B2
• Filed: 10/29/2007
• Issued: 01/03/2012
• Est. Priority Date: 09/03/2001
• Status: Expired due to Fees

• 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:
  US11/978,258
• Publication Number:
  US 20080145053A1
• Time in Patent Office: 1,527 Days
• Field of Search: 359290-295, 359/22, 359/279, 359/341.41, 359/349, 359/494, 359/495, 359/497, 359/498, 359/487, 359/558, 359/618, 359/337.21, 398 43- 50, 398/59, 398/72, 398/79, 398/82, 398/83, 398/176, 398/182, 398/183, 398/141, 398/195, 398/202, 398/203, 398/208, 398/209, 385 15- 18, 385/22, 385/24, 385/27, 385/33, 385/50, 385/125, 349/196, 250/227.23, 372/18, 372/20, 372/32
• US Class Current: 359/279
• 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] corresponding details, see subgroups of G03H2225/00
• 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 routing device having a first module, at least two second modules, a device input and at least two device outputs, the first and second modules each having an array of phase-modulating elements, the device input receiving an ensemble of optical channels on a common beam, the ensemble being formed by a multiplex of signals at different wavelengths, and the array of phase-modulating elements of the first module arranged to individually process the channels from the ensemble of optical channels at different wavelengths to route the channels to respective second modules for output as respective output ensembles of optical channels formed by a multiplex of signals on respective common beams.

2. The optical routing device of claim 1, wherein the array of phase-modulating elements of each second module is arranged to receive channels from the first module and to form from those channels the respective output ensembles.

3. The optical routing device of claim 1 further having at least two first modules, each receiving respective ensembles of optical channels formed by a multiplex of signals on respective common beams.

4. The optical routing device of claim 3, having more than two first modules.

5. The optical routing device of claim 1, defining optical paths between outputs of the first module and the second modules.

6. The optical routing device of claim 1, wherein each array of phase-modulating elements is formed by a respective LCOS SLM.

7. An optical routing device having at least two first modules, a second module, at least two device inputs and a device output, the first and second modules each having an array of phase-modulating elements, the device inputs receiving ensembles of optical channels formed by multiplexes of signals on a common beam and each connected to a respective first module, and the array of phase-modulating elements of the first modules are arranged to individually process the channels from the ensembles of optical channels at different wavelengths to route the channels to the second module for output as an ensemble of optical channels formed by a multiplex of signals on respective common beams.

8. The optical routing device of claim 7 used in one of the group comprising cross-connecting between ring networks, a mesh network and a hybrid ring/mesh network.

9. The optical routing device of claim 7, having plural input fibers and plural output fibers and having one first module for every input fiber and one second module for every output fiber.

10. A method of operating a routing device having plural modules, each having a respective array of phase-modulating elements, the routing device receiving one or more input ensembles of optical channels formed by a multiplex of signals on a common beam and providing one or more output ensembles of optical channels formed by a multiplex of signals on a common beam, the method comprising:

deflecting the channels using the arrays to provide a desired routing; and

adjusting beam deflections created by the phase-modulating elements of the array used to compensate for wavelength differences.

11. A method of operating a routing device having plural modules, each having a respective array of phase-modulating elements, the routing device receiving one or more input ensembles of optical channels formed by a multiplex of signals on a common beam and providing one or more output ensembles of optical channels formed by a multiplex of signals on a common beam, the method comprising:

deflecting the channels using the arrays to provide a desired routing; and

adjusting beam deflections created by the phase-modulating elements of the array used to compensate for alignment tolerances in said device.

12. A method of operating a routing device having plural modules, each having a respective array of phase-modulating elements, the routing device receiving one or more input ensembles of optical channels formed by a multiplex of signals on a common beam and providing one or more output ensembles of optical channels formed by a multiplex of signals on a common beam, the method comprising:

deflecting the channels using the arrays to provide a desired routing; and

applying independent channel equalization for all of the channels flowing through each module.

13. An add/drop device having a first module, a second module, a first device input and a first device output, the first and second modules each having a respective array of phase-modulating elements, the first device input receiving an input ensemble of optical channels formed by a multiplex of signals on a common beam, the array of phase-modulating elements of the first module arranged to individually process the channels from the ensemble of optical channels at different wavelengths to route selected channels to the second module for output as an output ensemble of optical channels formed by a multiplex of signals on a common beam.

14. The add/drop device of claim 13, wherein the array of phase-modulating elements of the second module is arranged to individually process channels from the first module for output as said output ensemble.

15. The add/drop device of claim 13, further having at least one further device output, wherein the array of phase-modulating elements of the first module is arranged to individually process the channels from the input ensemble of optical channels at different wavelengths to route selected channels to the at least one further device output.

16. The add/drop device of claim 15, further having at least one further device input, wherein the array of phase-modulating elements of the second module is arranged to individually process channels from the first module and from the at least one further device output for output as an ensemble of optical channels formed by a multiplex of signals on a common beam.

17. The add/drop device of claim 13, wherein each array of phase-modulating elements is formed by a respective LCOS SLM.

18. An optical device with an array of phase-modulating elements, the device having an input arranged to receive a multiplex of optical signals at different wavelengths in a common beam, the array of phase modulating elements being arranged to receive the optical signals of the multiplex from the device input, to separate the optical signals into at least two groups, and to process at least one of the groups of optical signals, wherein the array of phase-modulating elements is provided by a reflective LCOS SLM.

19. The optical device of claim 18, wherein the reflective LCOS SLM providing the array of phase-modulating elements comprises a two-dimensional array of pixels.

20. The optical device of claim 19 further comprising:

control circuitry operable to;

divide the reflective LCOS SLM into discrete blocks of pixels,

display holograms on respective blocks of pixels to determine channels at an output, and

select the size, shape or position of one or more of said blocks of pixels to achieve at least approximately a desired passband of a respective channel; and

a wavelength separation device disposed to receive light from the input and operable to disperse the multiplex of optical signals at different wavelengths in different directions.

21. The optical device of claim 20, wherein the control circuitry is operable to display a hologram on at least one of said respective blocks of pixels that is adapted to a wavelength of a channel associated with said block of pixels.

22. The optical device of claim 21, wherein the control circuitry is operable to display a hologram on at least one of said respective blocks of pixels to deflect a beam incident upon said block of pixels in a predetermined direction.

23. The optical device of claim 20, wherein the control circuitry is operable to display a first hologram on at least one of said respective blocks of pixels so as to achieve a first predetermined bandpass filter response with respect to a channel associated with said block of pixels.

24. The optical device of claim 23, wherein the control circuitry is operable to further display a second hologram on said at least one block of pixels so as to achieve a second predetermined bandpass filter response with respect to the wavelengths incident on said block of pixels.

25. The optical device of claim 19 further comprising:

control circuitry operable to;

divide the reflective LCOS SLM into discrete blocks of pixels,

display holograms on respective blocks of pixels to determine channels at an output, and

select the size, shape or position of one or more of said blocks of pixels to achieve at least approximately a desired center wavelength of a respective channel; and

a wavelength separation device disposed to receive light from the input and operable to disperse the multiplex of optical signals at different wavelengths in different directions.

26. The optical device of claim 25, wherein at least two blocks of pixels are associated with the same channel.

27. The optical device of claim 25, operable to align central wavelengths of different channels substantially at the centers of the respective different blocks of pixels of the reflective LCOS SLM.

28. The optical device of claim 19 further comprising:

control circuitry operable to;

divide the reflective LCOS SLM into a first arrangement of pixel blocks and display holograms on respective pixel blocks to determine channels at an output, wherein each of a plurality of said blocks is associated with a channel;

reconfigure the reflective LCOS SLM into a second arrangement of pixel blocks, wherein in the second arrangement of pixel blocks, at least one pixel is included in a pixel block associated with a channel having a different central wavelength than the channel associated with the pixel block with which the pixel was associated in the first arrangement; and

a wavelength separation device disposed to receive light from the input and operable to disperse the multiplex of optical signals at different wavelengths in different directions.

29. The optical device of claim 19 further comprising:

control circuitry operable to;

divide the reflective LCOS SLM into discrete blocks of pixels, and display holograms on respective blocks of pixels to determine channels at an output, wherein each of a plurality of said blocks is associated with a channel,

display a power control hologram on at least one block of pixels, wherein the power control hologram reflects an incident light beam, and

selectively control the attenuation of the incident light beam by varying the power control hologram; and

a wavelength separation device disposed to receive light from the input and operable to disperse the multiplex of optical signals at different wavelengths in different directions.

30. The optical device of claim 29, wherein displaying the power control hologram further includes displaying a routing hologram to determine channels at an output.

31. The optical device of claim 30, wherein selectively controlling the attenuation of the incident light beam further includes reflecting the incident light beam away from an output.

32. The optical device of claim 30, wherein selectively controlling the attenuation of the incident light beam further includes coupling unwanted power of the incident light beam into one or more modes of an output waveguide other than the fundamental mode.

33. The optical device of claim 30, wherein displaying the power control hologram and displaying the routing hologram further comprises displaying a corrective hologram, whereby a combined power control, routing and corrective hologram is arranged to correct for focus errors or aberrations in at least one dimension.

34. The optical device of claim 30, wherein the control circuitry is operable to selectively control the attenuation of plural channels so that the attenuation of a first channel in said plurality may be controlled independently of the attenuation of a second channel in said plurality.

35. The optical device of claim 29, wherein the reflective LCOS SLM includes a wave plate.

36. The optical device of claim 35, wherein the wave plate is a quarter wave plate.

37. The optical device of claim 19 further comprising:

a substantially non-reflective optical absorber;

control circuitry operable to;

divide the reflective LCOS SLM into discrete blocks of pixels and display holograms on respective pixel blocks to determine channels at the at least one output, wherein each pixel block is associated with a channel,

display a channel blocking hologram on at least one block of pixels, wherein the channel blocking hologram reflects substantially all of an incident light beam toward the substantially non-reflective optical absorber; and

a wavelength separation device disposed to receive light from the input and operable to disperse the multiplex of optical signals at different wavelengths in different directions.

38. The optical device of claim 19 further comprising:

control circuitry operable to;

divide the reflective LCOS SLM into discrete blocks of pixels and guardband blocks that are discrete from said blocks of pixels, and

display holograms on respective pixel blocks to determine channels at an output, wherein each of a plurality of said blocks is associated with a channel;

control the pixels in at least one guardband block to prevent light incident upon said guardband block from being directed to an output; and

a wavelength separation device disposed to receive light from the input and operable to disperse the multiplex of optical signals at different wavelengths in different directions.

39. The optical device of claim 38, wherein at least one guard band block is further configured to modify the spectrum of a channel associated with a pixel block.

40. The optical device of claim 19, further comprising:

control circuitry operable to;

divide the reflective LCOS SLM into discrete blocks of pixels;

display combined routing and corrective holograms on respective blocks to determine channels at an output, whereby the array of phase modulating elements is arranged to correct for focus errors or aberrations in at least one dimension and

select the combined routing and corrective holograms to reduce crosstalk; and

a wavelength separation device disposed to receive light from the input and operable to disperse the multiplex of optical signals at different wavelengths in different directions.

41. The optical device of claim 19, further comprising:

control circuitry operable to;

divide the reflective LCOS SLM into discrete blocks of pixels;

display combined routing and corrective holograms on respective blocks to determine channels at an output, whereby the array of phase modulating elements is arranged to correct for focus errors or aberrations in at least one dimension; and

select the combined routing and corrective holograms to compensate for deviations due to the SLM itself or curvature of the SLM substrate; and

a wavelength separation device disposed to receive light from the input and operable to disperse the multiplex of optical signals at different wavelengths in different directions.

42. The optical device of claim 19 further comprising:

control circuitry operable to;

divide the reflective LCOS SLM into discrete blocks of pixels,

display holograms on respective blocks of pixels to determine channels at an output, and control adjacent blocks to determine filtering effects between one or more pairs of adjacent channels at the output; and

a wavelength separation device disposed to receive light from the input and operable to disperse the multiplex of optical signals at different wavelengths in different directions.

43. The optical device of claim 19 further comprising:

control circuitry operable to;

divide the reflective LCOS SLM into discrete blocks of pixels,

display holograms on respective blocks of pixels to determine channels at an output, and

control adjacent blocks to determine the wavelength spectrum between one or more pairs of adjacent channels at the output; and

a wavelength separation device disposed to receive light from the input and operable to disperse the multiplex of optical signals at different wavelengths in different directions.

44. The optical device of claim 19 further comprising:

control circuitry operable to;

divide the reflective LCOS SLM into discrete blocks of pixels,

display holograms on respective blocks of pixels to determine channels at an output, and

control adjacent blocks to achieve substantially flat transmission between one or more pairs of adjacent channels at the output; and

a wavelength separation device disposed to receive light from the input and operable to disperse the multiplex of optical signals at different wavelengths in different directions.