Optical switching device with reconfigurable channel spacing

• US 7,929,108 B2
• Filed: 02/15/2008
• Issued: 04/19/2011
• Est. Priority Date: 02/15/2008
• Status: Active Grant

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Oclaro Incorporated (Lumentum Holdings Inc.)
• Inventors: Barbarossa, Giovanni
• Primary Examiner(s): STAHL, MICHAEL J
• Application Number:
  US12/032,238
• Publication Number:
  US 20090208169A1
• Time in Patent Office: 1,159 Days
• Field of Search: None
• US Class Current: 349/196
• CPC Class Codes: G02B 6/2713 cascade of polarisation selective or adjusting operations
• CPC Class Codes: G02B 6/2931 Diffractive element operating in reflection
• CPC Class Codes: G02F 1/0136 for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation G02F1/0353 takes precedence
• CPC Class Codes: G02F 1/13355 Polarising beam splitters [PBS]
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/31 Digital deflection, i.e. optical switchingG02F1/33 takes precedence
• CPC Class Codes: G02F 2201/122 having a particular pattern
• CPC Class Codes: G02F 2203/07 Polarisation dependent
• CPC Class Codes: G02F 2203/585 Add/drop devices
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems

Abstract

An optical switching device includes an array of liquid crystal macropixels, wherein each macropixel includes at least two liquid crystal subpixels. The subpixels may be controlled together to act as a single polarizing pixel, or independently to act as multiple polarizing pixels. When the switching device processes a WDM having a wide channel spacing, the subpixels are controlled together, and when the switching device processes a WDM having a narrow channel spacing, each subpixel is controlled independently.

Claims

1. An optical switching device, comprising:

a liquid crystal (LC) element operable in a first mode and a second mode and having a plurality of LC subpixels each of which is independently controllable, wherein at least two adjacent LC subpixels are controlled together in unison when the LC polarizing element is configured in the first mode to modulate the polarization of a light beam from a group of light beams having a first channel spacing, and each of the two adjacent LC subpixels is independently controlled when the LC polarizing element is configured in the second mode to modulate the polarization of a light beam from a group of light beams having a second channel spacing that is narrower than the first channel spacing; and

an optical element positioned in the optical path of the light beams for changing the optical path of the light beams based on a polarization state of the light beams.

2. The optical switching device of claim 1, wherein the optical element is selected from the group consisting of a birefringent crystal and a Wollaston prism.

3. The optical switching device of claim 1, wherein the LC subpixels are separated by a gap less than one micrometer.

4. The optical switching device of claim 1, wherein the at least two adjacent subpixels comprise three adjacent subpixels, and when the LC polarizing element is configured in a third mode, the first subpixel is configured to modulate the polarization of a first light beam, the second subpixel is configured to modulate the polarization of a second light beam, and the third subpixel is positioned between the first and second subpixels and is configured as a dummy region.

5. The optical switching device of claim 1, wherein the light beams are wavelength channels demultiplexed from a wavelength division multiplexed (WDM) optical signal.

6. The optical switching device of claim 1, wherein the gap between the LC subpixels includes a plurality of interleaving features.

7. The optical switching device of claim 6, wherein the interleaving features are selected from the group consisting of rectangular, triangular, semicircular, and sinusoidal features.

8. An optical switching device comprising:

at least one input port;

at least two output ports;

a liquid crystal (LC) array positioned between the input port and the output ports, the LC array including an array of macropixels each including a plurality of independently controllable LC subpixels, wherein the LC array is configured in a first mode to modulate the polarization of a light beam from a group of light beams having a first channel spacing, and in a second mode to modulate the polarization of a light beam from a group of light beams having a second channel spacing that is narrower than the first channel spacing; and

an optical element positioned in the optical path of the light beams for changing the optical path of the light beams based on a polarization state of the light beams,

wherein, in the first mode, the LC subpixels that form one macropixel are controlled in unison, and, in the second mode, each of the LC subpixels that form one macropixel is independently controlled.

9. The optical switching device of claim 8, wherein the optical element is selected from the group consisting of a birefringent crystal and a Wollaston prism.

10. The optical switching device of claim 8, wherein the LC subpixels are separated by a gap less than one micrometer.

11. The optical switching device of claim 8, wherein the LC array is configurable in a third mode and, in the third mode, a first of three adjacent subpixels is configured to modulate the polarization of a first light beam, a second of three adjacent subpixels is configured to modulate the polarization of a second light beam, and a third of three adjacent subpixels is positioned between the first and second subpixels and is configured as a dummy region.

12. The optical switching device of claim 8, wherein the light beams are wavelength channels demultiplexed from a WDM optical signal.

13. The optical switching device of claim 8, wherein the gap between the LC subpixels includes a plurality of interleaving features.

14. The optical switching device of claim 13, wherein the interleaving features are selected from the group consisting of rectangular, triangular, semicircular, and sinusoidal features.

15. The optical switching device of claim 8, wherein the at least two output ports comprise a first output port and a second output port, and the LC subpixels are configured to modulate the polarization of light beams so that essentially all optical energy contained in a light beam is directed to either the first output port or the second output port.