Tunable optical filter and method of manufacture thereof

• US 9,244,266 B2
• Filed: 12/03/2014
• Issued: 01/26/2016
• 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:
  US14/559,752
• Publication Number:
  US 20150085367A1
• Time in Patent Office: 419 Days
• Field of Search: 359/245, 359/260, 359/263
• US Class Current: 1/1
• 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 (Mg⅓ Nb⅔) O_3-x—Pb Ti O₃) and no more than 160 μm thick.

Claims

1. A tunable optical filter comprising:

first and second end substrates, each end substrate having an inner parallel surface arranged toward each other, said inner parallel surface covered by an electrode layer and a reflecting layer; and

an electro-optic ceramic substrate having first and second parallel surfaces arranged between said first and second end substrates, said electro-optic ceramic substrate no more than 160 μ

m thick;

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—

Pb Ti O₃).

3. 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.

4. 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 an electro-optic ceramic substrate to no more than 160 μ

m thick with first and second parallel surfaces; and

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.

5. The method of claim 4 wherein said electro-optical ceramic substrate comprises PMN-PT ((1−

x)Pb (Mg⅓

Nb⅔

) O_3-x—

Pb Ti O₃).

6. A miniature Fabry-Perot interferometer comprising:

first and second optically transparent plates, each plate having an inner parallel surface arranged toward each other, said inner parallel surface covered by an electrode layer and a reflecting layer; and

an electro-optic ceramic substrate having first and second parallel surfaces arranged between said first and second optically transparent plates, the electro-optic ceramic substrate no more than 160 μ

m thick, 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 controlling an optical distance between the reflecting layers on the inner parallel surfaces of the first and second optically transparent plates;

whereby the Fabry-Perot interferometer forms a tunable optical filter.

7. The miniature Fabry-Perot interferometer of claim 6 wherein the electro-optical ceramic substrate comprises PMN-PT ((1−

x)Pb (Mg⅓

Nb⅔

) O_3-x—

Pb Ti O₃).

8. The miniature Fabry-Perot interferometer of claim 6 further comprising first and second anti-reflection layers respectively covering said first and second parallel surfaces of said electro-optic ceramic substrate.

9. A method of manufacturing a miniature Fabry-Perot interferometer capable of operating as 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 an electro-optic ceramic substrate to no more than 160 μ

m thick with first and second parallel surfaces; and

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

10. The method of claim 9 wherein the electro-optical ceramic substrate comprises PMN-PT ((1−

x)Pb (Mg⅓

Nb⅔

) O_3-x—

Pb Ti O₃).