Tunable optical filter and method of manufacture thereof

• US 8,559,090 B2
• Filed: 07/31/2008
• Issued: 10/15/2013
• Est. Priority Date: 07/31/2008
• Status: Active Grant

• Current Assignee: Lightwaves 2020, Inc.
• Original Assignee: Lightwaves 2020, Inc.
• Inventors: Pan, Jing Jong
• Primary Examiner(s): SAHLE, MAHIDERE S
• Application Number:
  US12/184,192
• Publication Number:
  US 20100027096A1
• Time in Patent Office: 1,902 Days
• Field of Search: 359/245, 359/260, 359/263
• US Class Current: 359/260
• CPC Class Codes: B32B 2307/202 Conductive
• CPC Class Codes: B32B 2307/416 Reflective
• CPC Class Codes: B32B 2315/02 Ceramics
• CPC Class Codes: B32B 2551/00 Optical elements
• CPC Class Codes: B32B 37/144 using layers with different mechanical or chemical conditions or properties, e.g. layers with different thermal shrinkage, layers under tension during bonding constructional features for tensioning B32B38/1825
• CPC Class Codes: B32B 37/18 involving the assembly of discrete sheets or panels only
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G02B 1/11 Anti-reflection coatings
• 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 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: G02F 1/055 the active material being a ceramic G02F1/035 takes precedence
• CPC Class Codes: G02F 1/0551 Constructional details
• CPC Class Codes: G02F 1/0553 specially adapted for gating or modulating in optical waveguides
• CPC Class Codes: G02F 1/0556 specially adapted for a particular application
• CPC Class Codes: G02F 1/213 Fabry-Perot type
• CPC Class Codes: G02F 2201/38 Anti-reflection arrangements
• CPC Class Codes: G02F 2202/28 Adhesive materials or arrangements
• CPC Class Codes: G02F 2203/055 wavelength filtering
• CPC Class Codes: G02F 2203/21 Thermal instability, i.e. DC drift, of an optical modulator; Arrangements or methods for the reduction thereof

Abstract

A tunable optical filter is formed in the structure of an etalon. A thin electro-optic ceramic substrate is fixed between two end substrates. Each end substrate has an inner parallel surface toward said electro-optic ceramic substrate covered by an electrode layer and a reflecting layer. An adhesive which attaches the electro-optic ceramic substrate to each first and second end substrates has a consistency so as to avoid stress on the electro-optic ceramic substrate. A voltage imposed on the electro-optic ceramic substrate by the electrode layers on the inner parallel surfaces of the first and second end substrates effectively controls an optical distance between the reflective coating layers on the inner parallel surfaces of the first and second end substrates of the etalon structure. The electro-optic ceramic substrate is preferably PMN-PT ((1-x)Pb(Mg⅓Nb⅔)O_3-x—PbTiO₃) and no more than 160 μm thick.

Claims

1. A tunable optical filter comprising:

an electro-optic ceramic substrate having first and second parallel surfaces;

first and second end substrates arranged on either side of said electro-optic ceramic substrate, each end substrate having an inner parallel surface arranged toward said electro-optic ceramic substrate and an outer parallel surface arranged away from said electro-optic ceramic substrate, said inner parallel surface covered by an electrode layer and a reflecting layer; and

a soft adhesive attaching said electro-optic ceramic substrate to said first and second end substrates at discrete locations around a periphery of said electro-optic ceramic substrate, said adhesive having a consistency so as to avoid stress on said electro-optic ceramic substrate;

whereby a voltage imposed on said electro-optic ceramic substrate by said electrode layers on said inner parallel surfaces of said first and second end substrates effectively controls an optical distance between said reflecting layers on said inner parallel surfaces of said first and second end substrates.

2. The tunable optical filter of claim 1 wherein said electro-optical ceramic substrate comprises PMN-PT ((1-x)Pb(Mg⅓

Nb⅔

)O_3-x—

PbTiO₃).

3. The tunable optical filter of claim 1 wherein said electro-optic ceramic substrate is no more than 160 μ

m thick.

4. The tunable optical filter of claim 1 further comprising

first and second anti-reflection layers respectively covering said first and second parallel surfaces of said electro-optic ceramic substrate.

5. The tunable optical filter of claim 1 further comprising

a thermo-electro cooler unit coupled thermally to said electro-optic ceramic substrate and said first and second end substrates whereby said electro-optic ceramic substrate and said first and second end substrates are temperature-stabilized.

6. The tunable optical filter of claim 1 wherein said first and second end substrates comprise quartz or Si.

7. The tunable optical filter of claim 3 wherein said electro-optical ceramic substrate comprises PMN-PT ((1-x)Pb(Mg⅓

Nb⅔

)O_3-x—

PbTiO₃).

8. The tunable optical filter of claim 3 further comprising

first and second anti-reflection layers respectively covering said first and second parallel surfaces of said electro-optic ceramic substrate.

19. The tunable optical filter of claim 1 wherein said soft adhesive attaching said electro-optic ceramic substrate to said first and second end substrates at discrete locations around a periphery of said electro-optic ceramic substrate.

9. A method of manufacturing a tunable optical filter comprising:

depositing an electrode layer and a reflective coating layer on a flat surface of first and second end substrates;

arranging said first and second end substrates so that said flat surface of each end substrate faces each other with an electro-optic ceramic substrate having first and second parallel surfaces therebetween; and

attaching said electro-optic ceramic substrate to each flat surface of each first and second end substrates at discrete locations around a periphery of said electro-optic substrate with a soft adhesive having a consistency so as to avoid stress on said electro-optic ceramic substrate.

10. The method of claim 9 wherein said electro-optical ceramic substrate comprises PMN-PT ((1-x)Pb(Mg⅓

Nb⅔

)O_3-x—

PbTiO₃).

11. The method of claim 10 wherein said electro-optic ceramic substrate is no more than 160 μ

m thick.

12. The method of claim 9 further comprising:

polishing said first and second parallel surfaces of said electro-optic ceramic substrate flat.

13. The method of claim 12 further comprising:

covering said first and second parallel surfaces of said electro-optic ceramic substrate with anti-reflection layers.

14. A method of manufacturing a tunable optical filter comprising:

depositing an electrode layer and a reflective coating layer on a flat surface of first and second end substrates;

polishing first and second parallel surfaces of an electro-optic ceramic substrate to no more than 160 μ

m thick;

arranging said first and second end substrates so that said flat surface of each end substrate faces each other with said electro-optic ceramic substrate therebetween; and

attaching said electro-optic ceramic substrate to said first and second end substrates at discrete locations around a periphery of said electro-optic ceramic substrate with a soft adhesive.

15. The method of claim 14 wherein said electro-optical ceramic substrate comprises PMN-PT ((1-x)Pb(Mg⅓

Nb⅔

)O_3-x—

PbTiO₃).

16. A method of manufacturing a tunable optical filter comprising:

polishing flat parallel surfaces of an electro-optic ceramic substrate;

covering said parallel surfaces of said electro-optic ceramic substrate with anti-reflection layers;

arranging first and second end substrates having flat surfaces with said electro-optic ceramic substrate therebetween, a flat surface of each end substrate against an anti-reflection layer covering a flat parallel surface of said electro-optic ceramic substrate to minimize light reflection caused by air pockets between said electro-optic ceramic substrate and said first and second end substrates; and

attaching said electro-optic ceramic substrate to said first and second end substrates at discrete locations around a periphery of said electro-optic ceramic substrate with a soft adhesive.

17. The method of claim 16 wherein said electro-optical ceramic substrate comprises PMN-PT ((1-x)Pb(Mg⅓

Nb⅔

)O_3-x—

PbTiO₃).

18. The method of claim 16 further comprising:

prior to said arranging step, depositing an electrode layer and a reflecting layer on each flat surface of first and second end substrates.