Wavelength stabilization for broadband light sources

• US 7,326,915 B2
• Filed: 04/01/2005
• Issued: 02/05/2008
• Est. Priority Date: 04/01/2005
• Status: Expired due to Fees

• Current Assignee: EM4, Inc. (Gooch & Housego PLC)
• Original Assignee: EM4, Inc. (Gooch & Housego PLC)
• Inventors: Kaluzhny, Mikhail, Rosiewicz, Alex
• Primary Examiner(s): Epps; Georgia
• Assistant Examiner(s): WILLIAMS, DON J
• Application Number:
  US11/097,786
• Publication Number:
  US 20060219877A1
• Time in Patent Office: 1,040 Days
• Field of Search: 250/226, 250/214, 250/205, 250/227.14, 250/214.1, 250/216, 250/227.18, 250/227.23, 359/110, 359/187, 359/260, 359/307, 359/308, 385/12, 385/13, 385/15, 385/37, 356/320, 356/416
• US Class Current: 250/226
• CPC Class Codes: G01J 9/00 Measuring optical phase difference devices or arrangements for controlling the phase of light beams G02F1/01; Determining degree of coherence; Measuring optical wavelength spectrometry G01J3/00
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/0045 the devices being superluminescent diodes

Abstract

A broadband light source, such as a light-emitting diode (LED), such as a superluminescent light-emitting diode (SLED), has its mean wavelength stabilized by using a filter to pass a characteristic of the output of the source, detecting the filtered output, and adjusting a parameter affecting the wavelength of the source, such as drive current or temperature. A Gaussian or near-Gaussian filter can be used to obtain an intensity detection, or two narrowband filters can be used where one filter passes a wavelength greater, and one passes a wavelength less, than the desired mean wavelength.

Claims

1. An apparatus comprising:

a broadband light source for emitting light with a source mean wavelength;

a filter with a generally Gaussian spectral distribution for receiving light from the source for filtering the light to provide filtered light, the filter having a filter mean wavelength, the filter for filtering substantially all the light from the light source when the filter mean wavelength is substantially equal to the source mean wavelength;

a first detector for detecting the filtered light and for providing a signal indicative of a parameter of the filtered light; and

a control system responsive to the signal from the detector for controlling the mean wavelength of the light emitted from the source if the mean wavelength deviates from a desired value.

2. The apparatus of claim 1, wherein the filter is spaced from the detector and housed in a separate component.

3. The apparatus of claim 1, wherein the filter is formed on a surface of the detector.

4. The apparatus of claim 1, wherein the source includes a light emitting diode (LED).

5. The apparatus of claim 1, wherein the source includes a superluminescent light emitting diode (SLED).

6. The apparatus of claim 1, wherein the source is mounted to a thermo-electric cooler (TEC), the control system controlling the mean wavelength by controlling the temperature of the TEC.

7. The apparatus of claim 1, wherein the control system controls the mean wavelength by controlling a drive current to the source.

8. The apparatus of claim 1, further comprising a second detector, and a beam splitter between the source and the filter for providing a first beam to the first detector and a second beam to the second detector, the control system being responsive also to a signal from the second detector.

9. The apparatus of claim 1, further comprising an optical fiber for receiving light from the source.

10. The apparatus of claim 9, further comprising a generally Gaussian filter between the source and the optical fiber.

11. The apparatus of claim 1, further comprising a fiber optic gyroscope for receiving light from the source.

12. The apparatus of claim 11, wherein the source includes a light emitting diode (LED).

13. The apparatus of claim 11, wherein the source includes a superluminescent light emitting diode (SLED).

14. An apparatus comprising:

a broadband light source for emitting light with a mean wavelength;

a first narrowband filter for receiving light from the source and for passing light with a wavelength greater than the mean wavelength;

a second filter receiving light from the source and for passing light with a wavelength less than the mean wavelength;

a first detector for detecting light from the first filter and for providing a first signal;

a second detector for detecting light from the second filter and for providing a second signal; and

a control system responsive to the first and second signals and for controlling the mean wavelength of the light emitted from the source if the mean wavelength deviates from a desired value.

15. The apparatus of claim 14, wherein the source includes a light emitting diode (LED).

16. The apparatus of claim 14, wherein the source includes a superluminescent light emitting diode (SLED).

17. The apparatus of claim 14, further comprising a beam splitter for receiving a beam from the source and providing first and second beams to the first and second filters.

18. The apparatus of claim 14, wherein the source is mounted to a thermo-electric cooler (TEC), the control system controlling the mean wavelength by controlling the temperature of the TEC.

19. The apparatus of claim 14, wherein the control system controls the mean wavelength by controlling a drive current to the source.

20. The apparatus of claim 14, wherein each filter passes light with a wavelength where the intensity of the light from the source is about ⅔

of the peak intensity.

21. The apparatus of claim 14, further comprising a fiber optic gyroscope for receiving light from the source.

22. The apparatus of claim 21, wherein the source includes a light emitting diode (LED).

23. The apparatus of claim 21, wherein the source includes a superluminescent light emitting diode (SLED).