WAVELENGTH MONITORED AND STABILIZED SOURCE

• US 20090073537A1
• Filed: 09/14/2007
• Published: 03/19/2009
• Est. Priority Date: 09/14/2007
• Status: Active Grant

• Current Assignee: Weatherford Technology Holdings, LLC (Weatherford International PLC)
• Original Assignee: Weatherford/Lamb Incorporated (Weatherford International PLC)
• Inventors: Taverner, Domino
• Granted Patent: US 7,813,046 B2
• Time in Patent Office: Days
• US Class Current: 359/260
• CPC Class Codes: G01C 19/721 Details
• CPC Class Codes: H04B 10/572 Wavelength control

Abstract

Methods and apparatus for sampling techniques can constantly monitor a spectral output from a broadband source in order to control a central wavelength of interrogation light supplied by the source for input to a sensor. A first portion of light output from the broadband source passes through a controller module for spectral analysis and referencing to provide measurements that can be used as feedback to actively modify a second portion of the light from the source. This modified second portion thereby controls the central wavelength to ensure accurate determination of sensor response signals received at a receiver.

Claims

1. An optical system for producing a stabilized broadband light output to a sensor, comprising:

a broadband light source for producing broadband light signals;

a splitter dividing the light signals into first and second portions along first and second output pathways, respectively;

a controller module having a sweeping tunable filter coupled to the first output pathway of the splitter to receive the first portion of the light signals prior to outputting respective filtered light portions to a comb filter and a wavelength reference element, wherein control circuitry is configured to evaluate detected signals from the comb filter and the reference element to generate a control signal output; and

a wavelength dependent variable attenuator coupled to the second output pathway of the splitter and the control circuitry to receive the second portion of the light signals and the control signal output, wherein the attenuator is configured to modify the second portion of the light signals based on the control signal output, thereby providing the stabilized broadband light output.

2. The system of claim 1, wherein the attenuator is configured to output the stabilized broadband light output with all wavelengths of the source at one time.

3. The system of claim 1, wherein the comb filter includes a Fabry-Perot etalon.

4. The system of claim 1, wherein the wavelength reference element includes a Bragg grating.

5. The system of claim 1, wherein the wavelength reference element includes a Bragg grating and the comb filter includes a Fabry-Perot etalon.

6. The system of claim 1, wherein the first and second portions are unswept in time across wavelengths produced by the source.

7. The system of claim 1, wherein the source is an amplified spontaneous emission source.

8. The system of claim 1, further comprising a fiber-optic gyroscope that defines the sensor.

9. The system of claim 1, further comprising a detector coupled to the sweeping tunable filter to receive another filtered light portion, wherein the control circuitry is configured to evaluate spectral power measurements from the detector to generate the control signal output.

10-16. -16. (canceled)

17. A method of stabilizing broadband light output to a sensor, comprising:

generating a broadband light;

dividing the light into first and second pathways, wherein a controller module wavelength scans light propagating in the first pathway prior to outputting respective filtered light portions to a comb filter and a wavelength reference element of the controller module;

generating a control signal output with control circuitry based on detected signals from the comb filter and the reference element; and

modifying tight propagating in the second pathway based on the control signal output, thereby producing the stabilized broadband light output.

18. The method of claim 17, wherein the stabilized broadband light output contains a wavelength range of at least 10 nm emitted at one time.

19. The method of claim 17, wherein the modifying includes variably attenuating selective wavelengths.

20. The method of claim 17, further comprising receiving response signals from the sensor and analyzing the response signals to output a signal indicative of a sensed parameter.

21. The method of claim 17, further comprising receiving response signals from the sensor and analyzing the response signals to display to a user a sensed parameter.

22. The method of claim 17, wherein the controller module wavelength scans light propagating in the first pathway prior to outputting an additional filtered light portion to a detector making spectral power measurements utilized by the control circuitry in generating the control signal output based on the measurements.