Tilt-able grating plane for improved crosstalk in 1×N blaze switches

• US 6,927,891 B1
• Filed: 12/23/2002
• Issued: 08/09/2005
• Est. Priority Date: 12/23/2002
• Status: Active Grant

• Current Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Original Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Inventors: Maheshwari, Dinesh
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): CHOI, WILLIAM C
• Application Number:
  US10/327,762
• Time in Patent Office: 960 Days
• Field of Search: 359/224, 359/290, 359/291, 359/295, 359/298, 359/318, 359/572, 359/573
• US Class Current: 359/291
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements

Abstract

A light modulator includes elongated elements arranged parallel to each other. Each elongated element includes a light reflective planar surface with the light reflective planar surfaces configured in a first grating plane. A support structure is coupled to the elongated elements to maintain a position of the elongated elements relative to each other and to enable movement of each elongated element in a direction normal to the first grating plane. The support structure enables movement between a first modulator configuration and a second modulator configuration. In the first modulator configuration, the elongated elements act to reflect an incident light as a plane mirror. In the second modulator configuration, the elongated elements form a stepped blaze configuration along a second grating plane lying at a grating angle to the first grating plane and act to diffract the incident light into at least two diffraction orders.

Claims

1. A light modulator comprising:

a) a plurality of elongated elements, wherein each elongated element includes a light reflective planar surface with the light reflective planar surfaces configured in a first grating plane; and

b) a support structure coupled to the elongated elements to maintain a position of the elongated elements relative to each other and to enable movement of each elongated element between a first modulator configuration wherein the elongated elements act to reflect incident light, and a second modulator configuration wherein the elongated elements are configured into a plurality of stepped blaze elements such that each blaze element comprises a plurality of adjacent stepped elongated elements, and each of the blaze elements are stepped relative to the other blaze elements along a second grating plane lying at a tilted grating angle to the first grating plane and act to diffract the incident light into at least two diffraction orders.

2. The light modulator according to claim 1 wherein a diffraction angle of each diffraction order is dependent on the grating angle.

3. The light modulator according to claim 1 wherein the stepped blaze elements configuration includes a plurality of stepped blaze elements, further wherein each blaze element includes a plurality of adjacent stepped elongated elements configured as a stepped blaze grating.

4. The light modulator according to claim 3 wherein each blaze element is separated by a blaze element height difference from an adjacent blaze element.

5. The light modulator according to claim 4 wherein the grating angle is about an arctangent of the blaze element height difference divided by a blaze element pitch.

6. The light modulator according to claim 5 wherein the incident light impinges the elongated elements normal to the first grating plane such that the at least two diffraction orders comprise a first positive diffraction order at a first plus order blaze angle of about an arcsine of a difference of a wavelength of the incident light divided by the blaze element pitch and a sine of the grating angle, and a first negative diffraction order at a first negative order blaze angle of about an arcsine of a difference of a negative of the wavelength of the incident light divided by the blaze element pitch and the sine of the grating angle.

7. The light modulator according to claim 6 wherein the at least two diffraction orders further comprise a near zero order diffraction order at a near zero order blaze angle of about two times the grating angle.

8. The light modulator according to claim 5 wherein the blaze element pitch comprises a sum of a width of each elongated element within the blaze element.

9. The light modulator according to claim 3 wherein each elongated element within the blaze element is separated by a constant height difference.

10. The light modulator according to claim 3 wherein the stepped elongated elements within each blaze element form a positive slope and the stepped blaze elements form a positive slope.

11. The light modulator according to claim 3 wherein the stepped elongated elements within each blaze element form a negative slope and the stepped blaze elements form a negative slope.

12. The light modulator according to claim 3 wherein the stepped elongated elements within each blaze element form a positive slope and the stepped blaze elements form a negative slope.

13. The light modulator according to claim 3 wherein the stepped elongated elements within each blaze element form a negative slope and the stepped blaze elements form a positive slope.

14. The light modulator according to claim 1 wherein the light modulator comprises a diffractive light modulator.

15. The light modulator according to claim 1 wherein the stepped blaze elements include each of the plurality of elongated elements commonly tilted and progressively stepped along the second grating plane.

16. The light modulator according to claim 1 wherein each elongated element further comprises a first conductive element and the light modulator further comprises a substrate coupled to the support structure, the substrate comprising a second conductive element such that in operation an electrical bias applied between the first conductive element and the second conductive element enables selective actuation of each of the elongated elements.

17. A method of modulating light comprising:

a) supporting a plurality of elongated elements, each element includes a light reflective planar surface with the light reflective planar surfaces configured in a grating plane; and

b) configuring the plurality of elongated elements between a first modulator configuration wherein the elongated elements act to reflect an incident light, and a second modulator configuration wherein the elongated elements are configured into a plurality of stepped blaze elements such that each blaze element comprises a plurality of adjacent stepped elongated elements, and each of the blaze elements are stepped relative to the other blaze elements along a second grating plane lying at a tilted grating angle to the first grating plane and act to diffract the incident light into at least two diffraction orders.

18. The method according to claim 17 wherein the incident light impinges the elongated elements normal to the first grating plane such that the at least two diffraction orders comprise a first positive diffraction order at a first plus order blaze angle of about an arcsine of a difference of a wavelength of the incident light divided by the blaze element pitch and a sine of the grating angle, the grating angle is then subtracted from the arcsine result, and a first negative diffraction order at a first negative order blaze angle of about an arcsine of a difference of a negative of the wavelength of the incident light divided by the blaze element pitch and the sine of the grating angle, the grating angle is then subtracted from the arcsine result.

19. The method according to claim 18 wherein the at least two diffraction orders further comprise a near zero order diffraction order at a near zero order blaze angle of about two times the grating angle.

20. A light modulator comprising:

a) means for supporting a plurality of elongated elements, each element includes a light reflective planar surface with the light reflective planar surfaces configured in a grating plane; and

b) means for configuring the plurality of elongated elements between a first modulator configuration wherein the elongated elements act to reflect an incident light, and a second modulator configuration wherein the elongated elements are configured into a plurality of stepped blaze elements such that each blaze element comprises a plurality of adjacent stepped elongated elements, and each of the blaze elements are stepped relative to the other blaze elements along a second grating plane lying at a tilted grating angle to the first grating plane and act to diffract the incident light into at least two diffraction orders.