Interferometric modulation

• US 6,040,937 A
• Filed: 07/31/1996
• Issued: 03/21/2000
• Est. Priority Date: 05/05/1994
• Status: Expired due to Term

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Etalon, Inc.
• Inventors: Miles, Mark W.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Lester, Evelyn A.
• Application Number:
  US08/688,710
• Time in Patent Office: 1,329 Days
• Field of Search: 359/247, 359/248, 359/249, 359/250, 359/263, 359/290, 359/291, 359/295, 359/318, 359/320, 359/359, 359/578-580, 359/584-586, 359/589
• US Class Current: 359/291
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• 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 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means

Abstract

An interferometric modulator (Imod) cavity has a reflector and an induced absorber. A direct view reflective flat panel display may include an array of the modulators. Adjacent spacers of different thicknesses are fabricated on a substrate by a lift-off technique used to pattern the spacers which are deposited separately, each deposition providing a different thickness of spacer. Or a patterned photoresist may be used to allow for an etching process to selectively etch back the thickness of a spacer which was deposited in a single deposition. A full-color static graphical image may be formed of combined patterns of interferometric modulator cavities. Each cavity includes a reflector, and an induced absorber, the induced absorber including a spacer having a thickness that defines a color associated with the cavity.

Claims

1. An interferometric modulator comprising

a first element comprising a reflector, and

a second element including an induced absorber comprising a sandwich of an absorber between two matching layers,

at least one of the matching layers comprising a combination of at least two of;

a metal film, a dielectric film, and a semiconducting film, and

the reflector comprising at least one of a metal film, a dielectric film, and a semiconducting film.

3. The modulator of claim 1 or 2 wherein the second element comprises a film of metal.

4. The modulator of claim 1 or 2 wherein the second element comprises a dielectric film.

5. The modulator of claim 1 or 2 wherein the second element comprises a simconducting film.

6. The modulator of claim 1 or 2 wherein the second element comprises a combination of at least two of a metal film, a dielectric film, and a simconducting film.

7. The modulator of claim 1 or 2 wherein the the first element comprises a sandwich of an absorber between at least two matching layers.

8. The modulator of claim 7 wherein one of the matching layers resides at the boundary of the absorber with an incident medium and the other matching layer resides at the boundary of the absorber with the second element.

9. The modulator of claim 7 wherein at least one of the matching layers comprises a film of metal.

10. The modulator of claim 7 wherein at least one of the matching layers comprises a dielectric film.

11. The modulator of claim 7 wherein at least one of the matching layers comprises a semiconducting film.

12. The modulator of claim 7 wherein at least one of the matching layers comprises a combination of at least two of a metal film, a dielectric film, and a semiconducting film.

13. The modulator of claim 7 wherein the absorber comprises a high loss film including a metal.

14. The modulator of claim 7 wherein the absorber comprises a high loss film including a semiconductor.

15. The modulator of claim 7 wherein the absorber comprises a combination of a metal and semiconducting film.

16. The modulator of claim 1 or 2 further comprising a substrate bearing at least one of the first element and the second element.

17. The modulator of claim 16 wherein the substrate comprises a transparent medium.

18. The modulator of claim 16 wherein the substrate comprises an opaque medium.

19. The modulator of claim 16 wherein the induced absorber resides on the substrate.

20. The modulator of claim 16 wherein the reflector resides on the substrate.

2. An interferometric modulator comprising

a first element and a second element that cooperate to effect an optical response of the modulator to incident light received at the modulator via an incident medium,

the first element having an outer surface exposed to the incident medium and an internal surface facing an internal surface of the second element, the first element being configured to absorb predetermined wavelengths present in light that is received at the modulator via the incident medium.

21. The modulator of claim 2 in which the first and second elements are movable relative to each other to alter the distance between them to switch the modulator between first and second states.

22. The modulator of claim 21 in which, in the first of the states, the first element absorbs the predetermined wavelengths and returns other wavelengths of the incident light to the incident medium.

23. The modulator of claim 21 in which, in the second of the states, the first element matches the admittance of the second element to the admittance of the incident medium and the modulator returns essentially none of the incident light to the incident medium.

24. The modulator of claim 21 in which, in the first of the states, the second element serves as a reflector of the incident light.

25. The modulator of claim 21 in which, in the second of the states, the second element serves as a reflector of the incident light.

26. The modulator of claim 21 in which, in the second of the states, the distance between the first and second elements is essentially zero.