Variable multi-cavity optical device

• US 20020191268A1
• Filed: 05/17/2001
• Published: 12/19/2002
• Est. Priority Date: 05/17/2001
• Status: Abandoned Application

• Current Assignee: Optical Coating Laboratory, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Optical Coating Laboratory, Inc. (Lumentum Holdings Inc.)
• Inventors: Seeser, James W., Swaby, Basil L.
• Application Number:
  US09/860,923
• Publication Number:
  US 20020191268A1
• Time in Patent Office: Days
• US Class Current: 359/260
• 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: G02B 6/29395 configurable, e.g. tunable or reconfigurable switching G02B6/35
• CPC Class Codes: G02B 6/29398 Temperature insensitivity
• CPC Class Codes: G02F 1/0311 Structural association of optical elements, e.g. lenses, polarizers, phase plates, with the crystal
• CPC Class Codes: G02F 1/153 Constructional details
• CPC Class Codes: G02F 1/21 by interference
• CPC Class Codes: G02F 1/213 Fabry-Perot type
• CPC Class Codes: G02F 1/216 using liquid crystals, e.g. liquid crystal Fabry-Perot filters
• CPC Class Codes: G02F 2201/16 series; tandem
• CPC Class Codes: G02F 2201/346 distributed (Bragg) reflector

Abstract

A multi-cavity optical device allowing selective control of a bandpass characteristic thereof . Fabry-Perot structures are coherently coupled together to form a narrow bandpass structure. At least one of the spacer regions in the device includes an active material that changes the optical thickness of the spacer to de-tune the device. In one embodiment, the active material is transparent and lies along the optical path through the device. In another embodiment, an active material that lies outside of the optical path tunes an air gap. Altering the first or last spacer in a multi-cavity structure provides variation in the transmission loss while generally retaining a flattop filter response with low passband ripple. Altering interior spacer regions provides high sensitivity to variations in the optical thickness of the spacer.

Claims

1. A multi-cavity optical device comprising:

a first Fabry-Perot structure having a first reflector a first spacer and a second reflector optically coupled to

a second Fabry-Perot structure having a third reflector, a second spacer, and a fourth reflector, wherein the first spacer includes an active material capable of changing an optical thickness of the first spacer upon application of a control signal to the active material.

2. The multi-cavity optical device of claim 1 wherein the control signal in an electronic potential applied across at least a portion of the active material.

3. The multi-cavity optical device of claim 1 wherein the control signal is a light signal applied to at least a portion of the active material.

4. The multi-cavity optical device of claim 1 further comprising an optical input wherein the first Fabry-Perot structure is proximate to the optical input.

5. The multi-cavity optical device of claim 1 further comprising an optical output wherein the first Fabry-Perot structure is proximate to the optical output.

6. The multi-cavity optical device of claim 1 further comprising a third Fabry-Perot structure.

7. The multi-cavity optical device of claim 6 comprising an even number of Fabry-Perot structures.

8. The multi-cavity optical device of claim 1 further comprising a third Fabry-Perot structure, a fourth Fabry-Perot structure, and a fifth Fabry-Perot structure,

wherein the first Fabry-Perot structure is proximate to an optical input or to an optical output of the multi-cavity optical device.

9. The multi-cavity optical device of claim 1, wherein the first reflector includes an at least partially transparent electrically conductive material.

10. The multi-cavity optical device of claim 9 wherein the at least partially transparent electrically conductive material is selected from the group consisting of indium oxide, indium tin oxide, erbium doped silicon dioxide, and combinations thereof.

11. The multi-cavity optical device of claim 9 wherein the second reflector includes a second at least partially transparent electrically conductive material.

12. The multi-cavity optical device of claim 5 wherein the first spacer includes an air gap and the active material lies outside an optical path through the multi-cavity optical device.

15. The method of claim 14 wherein the changing step includes increasing the initial optical thickness to the second optical thickness.

16. The method of claim 14 wherein the changing step includes decreasing the initial optical thickness to the second optical thickness.

17. The method of claim 14 further comprising steps of:

applying a second control signal to the active spacer material; and

changing the second optical thickness to a third optical thickness.

18. The method of claim 14 wherein the initial optical thickness provides a first transmittance of between about 85-95% through the multi-cavity optical device and the second optical thickness provides a second transmittance of less than about 1% through the multi-cavity optical device.

19. The method of claim 14 wherein the initial optical thickness provides a first transmittance of between about 90-95% through the multi-cavity optical device and the second optical thickness provides a second transmittance of less than about 1% through the multi-cavity optical device.

20. The method of claim 18 wherein the second transmittance varies in proportion to the control signal.

13. A multi-cavity optical device, comprising:

a first Fabry-Perot structure including

a first reflector optically coupled to a first optical port of the multi-cavity optical device;

a first spacer proximate to and coupled to the first reflector and having an optical thickness, the first spacer including an active material capable of changing the optical thickness of the first spacer in response to a control signal;

a second reflector optically coupled to the first spacer;

a second Fabry-Perot structure disposed between and optically coupled to the first Fabry-Perot structure; and

a third Fabry-Perot structure disposed between and optically coupled to the second Fabry-Perot structure and a second optical port of the multi-cavity optical device.

14. A method of attenuating an optical signal, the method comprising:

providing an optical signal to a multi-cavity optical device having a first spacer region and a second spacer region, the first spacer region including an active material and the first spacer having an initial optical thickness;

applying a control signal to the active material; and

changing the initial optical thickness to a second optical thickness.

21. A method of switching a multi-cavity optical switch, the method comprising:

providing an optical signal to an input of the multi-cavity optical switch having a first spacer region and a second spacer region, the first spacer region including an active material and the first spacer having an initial optical thickness;

transmitting the optical signal from the input of the multi-cavity optical switch to an output of the multi-cavity optical switch;

applying a control signal to the active material;

changing the initial optical thickness to a second optical thickness; and

reflecting the optical signal off of the multi-cavity optical switch.

22. The method of claim 21 wherein the multi-cavity device is a narrow-band filter device with a relative transmission bandwidth of about 0.04% or less.

23. The method of claim 21 wherein the multi-cavity optical device has an odd number of Fabry-Perot structures and the first spacer is in a Fabry-Perot structure proximate to the input or to the output.

24. The method of claim 21 further comprising steps of:

removing the control signal; and

transmitting the optical signal through the multi-cavity optical switch.