Wavelength monitor utilizing a tunable bragg grating and blazed grating

• US 20020150336A1
• Filed: 03/16/2002
• Published: 10/17/2002
• Est. Priority Date: 03/16/2001
• Status: Active Grant

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Cidra Sarl (Nordic Cultural & Educational Foundation)
• Inventors: Kersey, Alan D., Davis, Michael A.
• Granted Patent: US 6,856,729 B2
• Time in Patent Office: Days
• US Class Current: 385/37
• CPC Class Codes: G02B 6/02176 due to temperature fluctuations
• CPC Class Codes: G02B 6/022 using mechanical stress, e.g. tuning by compression or elongation, special geometrical shapes such as "dog-bone" or taper G02B6/02204 takes precedence; optical modulation using photo-elastic effect G02F1/0131
• CPC Class Codes: G02B 6/2932 comprising a directional router, e.g. directional coupler, circulator
• CPC Class Codes: G02B 6/29322 Diffractive elements of the tunable type G02B6/02195 takes precedence; optical modulation devices based on a change of the optical properties of the medium G02F1/00
• CPC Class Codes: G02B 6/29323 Coupling to or out of the diffractive element through the lateral surface of the light guide evanescent grating couplers G02B6/29332
• CPC Class Codes: G02B 6/2938 for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
• CPC Class Codes: G02B 6/29385 Channel monitoring, e.g. by tapping channel monitoring in optical transmission systems H04B10/07
• CPC Class Codes: G02B 6/29398 Temperature insensitivity
• CPC Class Codes: G02B 6/4215 the intermediate optical elements being wavelength selective optical elements, e.g. variable wavelength optical modules or wavelength lockers G02B6/4246 takes precedence

Abstract

A wavelength monitoring device is provided having an optical reflecting element for reflecting an incoming optical signal to a detector, wherein the device features a narrowband optical reflecting element for reflecting only a narrowband portion of the incoming optical signal to the optical reflecting element. The narrowband optical reflecting element has a reflection function having a bandwidth and shape that determines the narrowband portion of the incoming optical signal. The narrowband optical reflecting element may be a Bragg grating for spectrally processing the incoming optical signal, while the optical reflecting element may be a blazed Bragg grating for reflecting the spectrally processing incoming optical signal to the detector. The detector determines an amount of optical power reflected by the Bragg grating and discriminates between reflections of individual gratings, and is a spatial filter for providing a direct correlation between individual detector elements and a specific wavelength range. The narrowband optical reflecting element includes a glass element having a Bragg grating arranged therein. The glass element may be either an optical fiber having a diameter of about 125 microns, or a large diameter waveguide having a diameter of at least about 0.3 millimeters.

Claims

1. A device having an optical reflecting element for reflecting an incoming optical signal to a detector, the device comprising:

a narrowband optical reflecting element for reflecting only a narrowband portion of the incoming optical signal to the optical reflecting element.

2. A device according to claim 1, wherein the optical reflecting element comprises a blazed Bragg grating and the narrowband optical reflecting element comprises a Bragg grating for spectrally processing the incoming optical signal.

3. A device according to claim 2, wherein the Bragg grating has a reflection function having a bandwidth and shape that determines the narrowband portion of the incoming optical signal.

4. A device according to claim 3, wherein the detector determines an amount of optical power reflected by the Bragg grating and discriminates between reflections of individual gratings.

5. A device according to claim 4, wherein the detector device comprises a spatial filter providing a direct correlation between individual detector elements and a specific wavelength range.

6. A device according to claim 1, wherein the narrowband optical reflecting element comprises a glass element having a Bragg grating arranged therein.

7. A device according to claim 6, wherein the glass element comprises a large diameter waveguide having a diameter of at least about 0.3 millimeters.

8. A device according to claim 6, wherein the glass element comprises an optical fiber having a diameter of about 125 microns.

9. A device according to claim 6, wherein the Bragg grating comprises multiple co-located Bragg gratings.

10. A device according to claim 6, wherein the Bragg grating comprises concatenated Bragg gratings.

11. A device according to claim 1, wherein the device further comprises an optical coupler arranged between the optical reflecting element and the narrowband optical reflecting element.

12. A device according to claim 1, wherein the narrowband optical reflecting element comprises a tunable glass compression element and actuator having a large diameter optical waveguide with a diameter of at least about 0.3 millimeters and a Bragg grating arranged therein.

13. A device according to claim 12, wherein the large diameter waveguide has a dogbone shape.

14. A device according to claim 12, wherein the tunable glass compression element and actuator includes a housing having the large diameter optical waveguide arranged therein.

15. A device according to claim 12, wherein the actuator includes a transducer that provides a compression force on the large diameter optical waveguide for tuning the Bragg grating.

16. A device according to claim 1, wherein the device is a wavelength monitoring device.

17. A device according to claim 12, wherein the tunable glass compression element and actuator also includes a position feedback circuit.

18. A device according to claim 2, wherein the device includes an athermal device having the large diameter optical waveguide with the blazed grating and the detector arranged therein.

20. A wavelength monitoring device according to claim 19, wherein the Bragg grating element has a reflection function having a bandwidth and shape that determines the narrowband portion of the incoming optical signal.

21. A wavelength monitoring device according to claim 19, wherein the Bragg grating element includes a glass element having a Bragg grating arranged therein.

22. A wavelength monitoring device according to claim 21, wherein the optical detector determines an amount of optical power reflected by the Bragg grating and discriminates between reflections of individual gratings.

23. A wavelength monitoring device according to claim 19, wherein the optical detector is a spatial filter for providing a direct correlation between individual detector elements and a specific wavelength range.

24. A wavelength monitoring device according to claim 19, wherein the wavelength monitoring device further comprises a coupling device arranged between the Bragg grating element and the blazed grating element.

19. A wavelength monitoring device, comprising:

a Bragg grating element that responds to an incoming optical signal and reflects only a narrowband portion thereof;

a blazed grating element for reflecting the narrowband portion of the incoming optical signal; and

an optical detector that responds to the narrowband portion of the incoming optical signal, for monitoring the wavelength of the incoming optical signal.