High contrast grating light valve type device

• US 7,177,081 B2
• Filed: 03/08/2001
• Issued: 02/13/2007
• Est. Priority Date: 03/08/2001
• Status: Expired due to Term

• Current Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Original Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Inventors: Hunter, James, Amm, David Thomas, Tomita, Akira, Staker, Bryan, Daneman, Michael J.
• Primary Examiner(s): Dunn; Drew
• Assistant Examiner(s): AMARI, ALESSANDRO V
• Application Number:
  US09/802,619
• Publication Number:
  US 20040001257A1
• Time in Patent Office: 2,168 Days
• Field of Search: 359/572, 359/573, 359/224, 359290-295
• US Class Current: 359/572
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• CPC Class Codes: G02B 5/1828 having means for producing variable diffraction controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955

Abstract

A grating light valve has with a plurality of spaced reflective ribbons are spatially arranged over a substrate with reflective surfaces. The grating light valve is configured to optimized the conditions for constructive and destructive interference with an incident light source having a wavelength λ. The grating light valve preferably has a set of movable active ribbons alternating between the set of stationary bias ribbons. The active ribbons and the bias ribbons are spatially separated over the substrate surface such that reflective regions of the substrate surface correspond to the spaces between the ribbons. The ribbons and reflective regions of the substrate optically and geometrically optimized for to generate the conditions for constrictive and destructive interference with the incident light source. Accordingly, ribbons of the active ribbons are configured with reflective cross sections that are is approximately equal to the sum of the diffraction cross sections of the bias ribbons and the reflective regions of the substrate. In operation, active ribbons are moved by a multiple of λ/4 to switch between the conditions for constructive and destructive interference.

Claims

1. A light modulator comprising a diffraction region comprising a first set of ribbons each with a reflective surface area E_a and second set of ribbons each with a reflective surface area E_b, wherein the first set and second set of ribbons are alternating and spaced over a reference surface with a reflective surface regions having reflective surface areas E_s between each alternating ribbon of the first set and second set and wherein E_a is approximately equal to the sum of E_b and E_s, E_b is greater than or equal to E_s and E_s is not equal to zero.

2. The light modulator of claim 1, wherein the ribbons of the first set and the ribbons of the second set are elongated, wherein the ribbons of the first set each have an average width W_a, the ribbons of the second set each have an average width W_b and alternating ribbons of the first set and second set are separated by an average distance W_s.

3. The light modulator of claim 2, wherein W_a is approximately equal to the sum of W_b and W_s.

4. The light modulator of claim 2, wherein the first set of ribbons is configure to move by a multiple of λ

/4 relative to the reference surface of a substrate by applying a bias voltage across the first set of ribbons and the substrate element.

5. The light modulator of claim 4, wherein the second set of ribbons is configure to move a multiple of λ

/4 relative to the reference surface of the substrate by applying a bias voltage across the second set of ribbons the reference surface.

6. The light modulator of claim 1, wherein the top surfaces of the ribbons in the first set the top surfaces of the ribbons in the second set and regions of the reference surface between the alternating ribbons of the first set and the second set have reflective metallized layers.

7. The light modulator of claim 6, wherein the reflective metallized layers comprise Aluminum.

8. A method of modulating light with a wavelength λ

a comprising the steps of;

a. suspending a first set of reflective ribbons by a first distance corresponding to a multiple of λ

/2 over a reference surface with reflective regions, wherein each ribbon of the first set has a first reflective cross section;

b. suspending a second set reflective ribbons by a second distance corresponding to a multiple λ

/2 over the reference surface, wherein each ribbon of the second set has a second reflective cross section and wherein the first set and the second set of ribbons are spatially arranged such that the ribbon of the first set and the second set are alternating and spaced with reflective regions of the reference surface aligned with the spaces between the ribbon of the first set and the second set of ribbons, wherein the first reflective cross section is approximately equal to the sum of the second reflective cross section and the reflective region of the reference surface;

c. shining a light an incident light source with a wavelength λ

on the reflective surfaces of the first set of ribbons and the second set of ribbons; and

d. moving the first set of reflective ribbons relative to the second set of reflective ribbons by a multiple of distance λ

/4.

9. The method of claim 8, wherein the step of alternating the first set of reflective ribbons relative to the second set of reflective ribbon is accomplished by applying a sufficient bias to at least one set of the reflective ribbons.

10. The method of claim 8, wherein the incident light source has a wave length between 300 and 4000 nanometers.