High finesse holographic fabry-perot etalon and method of fabricating

• US 5,293,272 A
• Filed: 08/24/1992
• Issued: 03/08/1994
• Est. Priority Date: 08/24/1992
• Status: Expired due to Term

• Current Assignee: Sanwa Bank California (BNP Paribas S.A.)
• Original Assignee: Physical Optics Corporation
• Inventors: Aye, Tin M., Hirsh, Jay W., Jannson, Tomasz P., Rich, Christopher C.
• Primary Examiner(s): Arnold, Bruce Y.
• Assistant Examiner(s): COLLINS, DARRYL J
• Application Number:
  US07/934,793
• Time in Patent Office: 561 Days
• Field of Search: 359/1, 359/3, 359/22, 359/30, 359/900, 356/347
• US Class Current: 359/1
• CPC Class Codes: G01B 9/021 using holographic techniques
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02B 6/29358 Multiple beam interferometer external to a light guide, e.g. Fabry-Pérot, etalon, VIPA plate, OTDL plate, continuous interferometer, parallel plate resonator G02B6/29347, G02B6/29349, G02B6/2935, G02B6/29361 take precedence; resonator evanescently coupled to light guide G02B6/29335
• CPC Class Codes: G02B 6/29395 configurable, e.g. tunable or reconfigurable switching G02B6/35
• CPC Class Codes: Y10S 359/90 Methods

Abstract

A high finesse holographic Fabry-Perot etalon and method of making a high finesse holographic Fabry-Perot etalon is disclosed. Particularly, a holographic Fabry-Perot etalon which achieves high finesse despite non-flat interfaces between the etalon media is presented. In a preferred method of fabricating a high finesse Fabry-Perot etalon, single step recording of both holograms simultaneously, with the spacer and substrates in place, is employed which preserves full phase synchronization between the holograms. In spite of imperfections or irregularities of the interface surfaces of the substrates or spacers, the holographic fringes in the holograms remain flat even for slightly different refractive indices between the various media. The position and flatness of the fringes remains similar to perfect Fabry-Perot etalon structure.

Claims

1. A method of fabricating a high finesse holographic Fabry-Perot etalon comprising the steps of:

providing a first flat having a front surface and an interface surface, the front surface having high optical quality on the order of λ

/100 and the interface surface having moderate optical quality on the order of λ

/10;

providing a second flat having a back surface and an interface surface both surfaces having moderate optical quality on the order of λ

/10;

coating the interface surfaces of the first and second flats;

providing a mirror having high optical quality on the order of λ

/100;

providing a spacer having moderate optical quality surfaces on the order of λ

/10;

joining together the first flat, second flat, spacer, and mirror such that the spacer is sandwiched between the interface surfaces of the first and second flats, with an index matching medium between the spacer and each flat, and such that the back surface of the second flat is joined with the mirror with an index matching layer between the mirror and the second flat;

recording the coatings on the first and second flats using a single step holographic recording process; and

,

removing the mirror.

2. The invention as defined in claim 1 further characterized in that the coating is a photopolymer.

3. The invention as defined in claim 1 further characterized in that the coating is a dichromated gelatin.

4. The invention as defined in claim 1 wherein the spacer is an electrooptic material.

5. The invention as defined in claim 1 wherein the spacer is air.

6. The invention as defined in claim 1 wherein the spacer is liquid crystal.

7. The invention as defined in claim 1 wherein the spacer is PbLa(TiZr)O₃.

8. The invention as defined in claim 1 wherein the spacer is a piezoelectric material.

9. The invention as defined in claim 1 wherein the spacer is a material the refractive index of which is affected by light.

11. The invention as defined in claim 2 further characterized in that the holographic material is a photopolymer.

12. The invention as defined in claim 2 further characterized in that the holographic material is dichromated gelatin.

13. The invention as defined in claim 2 wherein the spacer is an electrooptic material.

10. A method of fabricating a high finesse holographic Fabry-Perot etalon comprising the steps of:

providing a spacer having two sides, each of moderate surface quality on the order of λ

/10;

coating each side of the spacer with a holographic material;

providing a flat having a front surface and an interface surface, the front surface being of high optical quality on the order of 80 /100 and the interface surface being of moderate optical quality on the order of λ

/10;

providing a mirror having high optical quality on the order of λ

/100;

joining the flat, spacer, and mirror such that the spacer is sandwiched between the interface surface of the flat and the mirror, with an index matching medium between the spacer and mirror and between the spacer and interface surface;

recording the holographic material using a one step holographic recording process; and

,

removing the mirror.

14. The invention as defined in claim 10 wherein the spacer is liquid crystal.

15. The invention as defined in claim 10 wherein the spacer is PbLa(TiZr)O₃.

16. The invention as defined in claim 10 wherein the spacer is a piezoelectric material.

17. The invention as defined in claim 10 wherein the spacer is a material the refractive index of which is affected by light.

18. A method of fabricating a tunable high finesse holographic Fabry-Perot etalon comprising the steps of:

providing a first flat having a front surface and an interface surface, the front surface having high optical quality on the order of λ

/100 and the interface surface having moderate optical quality on the order of λ

/10;

providing a second flat having a back surface and an interface surface both surfaces having moderate optical quality on the order of λ

/10;

coating the interface surfaces of the first and second flats;

providing a mirror having high optical quality on the order of λ

/100;

providing a spacer having moderate optical quality surfaces on the order of λ

/10, the spacer comprising electrooptic means;

joining together the first flat, second flat, spacer, and mirror such that the spacer is sandwiched between the interface surfaces of the first and second flats, with an index matching medium between the spacer and each flat, and such that the back surface of the second flat is joined with the mirror with an index matching layer between the mirror and the second flat;

recording the coatings on the first and second flats using a single step holographic recording process; and

,

removing the mirror.

19. A method of fabricating a high finesse holographic Fabry-Perot etalon having slanted fringes comprising the steps of:

providing a flat having a front surface and an interface surface, the front surface having high optical quality on the order of λ

/100 and the interface surface having moderate optical quality on the order of λ

/10;

providing a spacer having two sides, each of moderate optical quality on the order of λ

/10;

coating each side of the spacer with a holographic material to form a coated spacer;

providing a curved mirror having high optical quality on the order of λ

/100;

joining together the flat, coated spacer, and curved mirror such that the spacer is sandwiched between the interface surface of the flat and the mirror, with an index matching medium between the spacer and the flat, and between the spacer and the mirror;

recording the holographic material using a single step holographic recording process.

20. A method of fabricating a curved high finesse holographic Fabry-Perot etalon comprising the steps of:

providing a curved spacer having two sides, each of moderate surface quality on the order of λ

/10;

coating each side of the spacer with a holographic material to form a coated spacer;

providing a flat having a front surface and an interface surface, the front surface being of high optical quality on the order of λ

/100 and the interface surface being of moderate optical quality on the order of λ

/10;

providing a curved mirror having high optical quality on the order of λ

/100;

joining the flat, coated spacer, and mirror such that the coated spacer is sandwiched between the interface surface of the flat and the mirror, with an index matching medium between the coated spacer and mirror and between the coated spacer and interface surface;

recording the holographic material using a one step holographic recording process; and

,

removing the mirror.

21. A holographic Fabry-Perot etalon which yields high quality reflected wavefronts despite wavefront deformation within the etalon medium, the Fabry-Perot etalon comprising:

a spacer having first and second sides each coated with a holographic material;

a flat having a front surface and an interface surface, the interface surface of the flat being adjacent the holographic material on the first side;

a phase conjugate mirror adjacent the holographic material of the second side.

22. A spatial light modulator comprising:

a plurality of tunable Fabry-Perot etalons arranged in an array;

each of the etalons comprising a first flat having coated thereon a first holographic material;

a metal electrode mounted on the holographic material;

an electrooptic material mounted on the metal electrode;

a second metal electrode mounted on the electrooptic material;

a second flat one side of which is coated with a second holographic material and the second holographic material mounted to the second metal electrode; and

multi-pixel voltage driving means for driving each tunable Fabry-Perot etalon independently of the other etalons.