Optical processing

• US 7,664,395 B2
• Filed: 09/01/2006
• Issued: 02/16/2010
• 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): AMARI, ALESSANDRO V
• Application Number:
  US11/514,725
• Publication Number:
  US 20070035803A1
• Time in Patent Office: 1,264 Days
• Field of Search: 359/15, 359/19, 359/9, 359/569, 359/566, 359/572, 359/571, 359/244, 349/201, 349/202, 398/48, 398/49, 398/79, 398/81, 398/82, 398/84, 398/87
• US Class Current: 398/49
• 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

To operate an optical device comprising an SLM with a two-dimensional array of controllable phase-modulating elements groups of individual phase-modulating elements are delineated, and control data selected from a store for each delineated group of phase-modulating elements. The selected control data are used to generate holograms at each group and one or both of the delineation of the groups and the selection of control data is/are varied. In this way upon illumination of the groups by light beams, light beams emergent from the groups are controllable independently of each other.

Claims

1. An optical routing module having at least one input and at least one output and operable to select between the outputs, the or each input receiving a respective light beam having an ensemble of different channels, the module comprising:

a Spatial Light Modulator (SLM) having a two dimensional array of pixels,

a dispersion device disposed to receive light from said at least one input and constructed and arranged to disperse light beams of different frequencies in different directions whereby different channels of said ensemble are incident upon respective different groups of the pixels of the SLM, and

circuitry constructed and arranged to display holograms on the SLM to determine the channels at respective outputs.

2. The optical routing module of claim 1, wherein the dispersion device comprises at least one reflective device and at least one transmissive device.

3. The optical routing module of claim 1, wherein the dispersion device comprises at least one of:

a blazed grating, a holographic grating, an etched grating, an arrayed waveguide grating and a prism.

4. The optical routing module of claim 1, wherein the two dimensional SLM having an array of pixels is a reflective SLM incorporating a wave-plate whereby the reflective SLM is substantially polarisation independent.

5. The optical routing module of claim 1, wherein the two dimensional SLM having an array of pixels is a reflective Liquid Crystal on Silicon Spatial Light Modulator (LCOS SLM).

6. The optical routing module of claim 1, further comprising a wave-plate arranged such that light passes through the wave-plate first after passing through the dispersion device a first time, and second before passing through the dispersion device a second time.

7. The optical routing module of claim 6, wherein the dispersion device comprises a first and a second dispersion element.

8. The optical routing module of claim 1, further comprising a wave-plate arranged such that light passes through the wave-plate a first time after passing through a first dispersion element, and a second time before passing through a second dispersion element.

9. The optical routing module of claim 8, wherein the first and second dispersion elements are provided by a single dispersive device.

10. The optical routing module of claim 8, wherein the first and second dispersion elements are provided by separate dispersive devices.

11. The optical routing module of claim 1, wherein the beams of different frequencies are spatially separated when incident upon the array of pixels according to their respective wavelengths.

12. The optical routing module of claim 1, wherein a plurality of input beams are provided from a respective plurality of inputs and the beams are spatially separated when incident upon the array of pixels according to at least one of:

their respective input directions; and

their respective wavelengths.

13. The optical routing module of claim 1, wherein at least one group of pixels defines a square.

14. The optical routing module of claim 1, wherein at least one group of pixels defines an arbitrary shape.

15. The optical routing module of claim 1, wherein at least one group of pixels defines a rectangle.

16. The optical routing module of claim 1, wherein at least one group of pixels has a size between 10 and 50 phase modulating elements in at least one dimension.

17. The optical routing module of claim 1, wherein at least one group of pixels has a size in one dimension that is at least 2 times a 1/e spot half-width of an amplitude distribution of an incident beam measured in the same dimension.

18. The optical routing module of claim 1, wherein a property of at least one group of pixels is varied, the property including at least one of:

size, shape and position.

19. The optical routing module of claim 1, wherein each group of pixels comprises a plurality of subgroups, wherein at least one subgroup is controlled so as to have a phase effect different to at least one other subgroup.

20. The optical routing module of claim 1, further comprising a control device operable to delineate groups of individual phase-modulating elements;

to select, from stored control data, control data for each group of phase-modulating elements;

to generate from the respective selected control data a respective hologram at each group of phase-modulating elements; and

to vary at least one of the delineation of the groups and the selection of control data whereby upon illumination of said groups by respective light beams, respective emergent light beams from the groups are controllable independently of each other.

21. The optical routing module of claim 1, having groups of pixels of the two-dimensional SLM assigned to respective wavelength channels, and further comprising a control circuit operable to delineate guard bands between said groups.

22. The optical routing module of claim 21, wherein at least one guard band is configured to route light in a direction different to respective directions routed by said groups.

23. The optical routing module of claim 21, wherein at least one guard band is effective to narrow a bandwidth of a wavelength channel carried by a group of pixels.

24. A routing device having an input and plural outputs, the input constructed and arranged to receive an input light beam having plural frequencies, the device comprising:

a two dimensional Spatial Light Modulator (SLM) having an array of pixels, and

a dispersion device disposed to receive light from said at least one input and constructed and arranged to disperse beams of said light of different frequencies in different directions to be incident upon a respective different group of the pixels of the two-dimensional SLM,

wherein the routing device is operable to select the frequencies of the input light beam to appear in the outputs, wherein each output may contain any desired set of the plural frequencies.

25. A routing device according to claim 24, wherein the members of the desired set may be varied in use.

26. A routing device according to claim 24, wherein at least two of the outputs contain at least one common frequency.

27. A routing device having plural input signals and an output, the output constructed and arranged to deliver a signal having plural frequencies, the device comprising:

a two dimensional Spatial Light Modulator (SLM) having an array of pixels, and

a dispersion device disposed to receive light from the input signals and constructed and arranged to disperse beams of said light of different frequencies in different directions to be incident upon a respective different group of the pixels of the two-dimensional SLM,

wherein the routing device is operable to combine the frequencies from the input signals to appear in the output, wherein each input signal may contain any desired set of the plural frequencies of the output.