Temperature and optical length control of optical fibers and optical waveguide devices

• US 6,317,548 B1
• Filed: 03/11/1999
• Issued: 11/13/2001
• Est. Priority Date: 03/11/1999
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Minden, Monica L., Rockwell, David A.
• Primary Examiner(s): Bovernick, Rodney
• Assistant Examiner(s): PAK, SUNG H
• Application Number:
  US09/266,238
• Time in Patent Office: 978 Days
• Field of Search: 385/123, 385/124, 385/5, 385/9, 385/11, 385/14, 385/42, 385/37, 372/6, 359/341
• US Class Current: 385/123
• CPC Class Codes: G02B 6/02 Optical fibres with cladding with or without a coating
• CPC Class Codes: G02B 6/02171 characterised by means for compensating environmentally induced changes
• CPC Class Codes: G02B 6/02176 due to temperature fluctuations
• CPC Class Codes: G02B 6/2861 using fibre optic delay lines and optical elements associated with them, e.g. for use in signal processing, e.g. filtering delay lines in general H03H, H01P9/00; optical computing devices G06E
• CPC Class Codes: G02F 1/0115 in optical fibres
• CPC Class Codes: G02F 1/0126 Opto-optical modulation, i.e. control of one light beam by another light beam, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/0147 based on thermo-optic effects G02F1/132 takes precedence
• CPC Class Codes: G02F 1/2252 in optical fibres

Abstract

An optical fiber has a concentration of dopant ions residing within its core region. The dopant ions absorb optical energy at an excitation wavelength, converting that optical energy to heat and/or a change in the index of refraction and optical length of the optical fiber. Optical energy of the excitation wavelength is transmitted through the optical fiber simultaneously or sequentially with optical energy of a signal wavelength different from the excitation wavelength. The optical energy of the excitation wavelength controls the temperature of the optical fiber and/or its optical length as a result of (a) the temperature dependence of the refractive index and the physical length of the optical fiber, and (b) the change in polarizability of the optical fiber medium (and hence its refractive index) due to a change in the population distribution among the energy levels of the dopant ions.

Claims

1. An optical fiber device, comprising:

a first optical fiber having a first-fiber core region transmissive to optical energy of a signal wavelength and absorptive to optical energy of an excitation wavelength different from the signal wavelength, the first optical fiber comprising a concentration of dopant ions residing within the core region, the dopant ions being operable to absorb optical energy at the excitation wavelength;

a first source of optical energy of the excitation wavelength coupled into the first-fiber core region of the first optical fiber, the first source of optical energy being operable in a first state with a first power output and operable in a second state with a second power output different from the first power output; and

a second source of optical energy of the signal wavelength coupled into the first-fiber core region of the first optical fiber.

2. The optical fiber device of claim 1, wherein the optical fiber device further comprises

a second optical fiber.

3. The optical fiber device of claim 2, wherein the second optical fiber comprises

a second-fiber core region having resident therein substantially the same concentration of the dopant ions as in the first-fiber core region of the first optical fiber.

4. The optical fiber device of claim 2, wherein the first source of optical energy of the excitation wavelength is not coupled into the second optical fiber.

5. The optical fiber device of claim 2, wherein an optical path length of the first optical fiber is different from an optical path length of the second optical fiber.

6. The optical fiber device of claim 1, wherein the first optical fiber comprises one arm of an interferometer.

7. The optical fiber device of claim 1, wherein the first optical fiber is a discrete optical fiber.

8. The optical fiber device of claim 1, wherein the first optical fiber is a waveguide of an integrated optical waveguide.

9. The optical fiber device of claim 1, further including:

a controller operable to control the first source of optical energy.

10. The optical fiber device of claim 1, wherein the first source of optical energy is longitudinally coupled into the first-fiber core region so that the optical energy of the excitation wavelength travels along the length of the first optical fiber.

11. The optical fiber device of claim 1, wherein the first optical fiber comprises an element of a fiber Bragg grating.

12. The optical fiber device of claim 1, wherein the first optical fiber comprises an element of a coherent laser radar.

13. The optical fiber device of claim 1, wherein the first optical fiber comprises an element of an optical fiber array.

14. An optical fiber device, comprising:

a first optical fiber comprising one arm of an interferometer and having a first-fiber core region transmissive to optical energy of a signal wavelength and absorptive to optical energy of an excitation wavelength different from the signal wavelength, the first optical fiber comprising a concentration of dopant ions residing within the first-fiber core region, the dopant ions being operable to absorb optical energy at the excitation wavelength;

a second optical fiber having a second-fiber core region transmissive to optical energy of the signal wavelength and absorptive to optical energy of the excitation wavelength different from the signal wavelength;

a first source of optical energy of the excitation wavelength coupled into the first optical fiber, the first source of optical energy being operable in a first state with a first power output and operable in a second state with a second power output different from the first power output; and

a second source of optical energy of the signal wavelength coupled into the first optical fiber and the second optical fiber.

15. The optical fiber device of claim 14, wherein the first source of optical energy is coupled into the first optical fiber but not into the second optical fiber.

16. The optical fiber device of claim 14, wherein the second optical fiber comprises

a second-fiber core region having resident therein substantially the same concentration of the dopant ions as in the first-fiber core region of the first optical fiber.

17. The optical fiber device of claim 14, wherein a second optical path length of the second optical fiber is different from a first optical path length of the first optical fiber.

18. An optical fiber device, comprising:

a first optical fiber having a first-fiber core region transmissive to optical energy of a signal wavelength and absorptive to optical energy of an excitation wavelength different from the signal wavelength, the first optical fiber comprising a concentration of dopant ions residing within the first-fiber core region, the dopant ions being operable to absorb optical energy at the excitation wavelength;

a second optical fiber having a second-fiber core region transmissive to optical energy of the signal wavelength and absorptive to optical energy of the excitation wavelength different from the signal wavelength;

a first source of optical energy of the excitation wavelength coupled into the first optical fiber, the first source of optical energy being operable in a first state with a first power output and operable in a second state with a second power output different from the first power output;

a second source of optical energy of the signal wavelength coupled into the first optical fiber and the second optical fiber; and

a third source of optical energy of the excitation wavelength coupled into the second optical fiber.

19. A method for operating an optical fiber device, comprising the steps of

providing an optical fiber device including

a first optical fiber having a first-fiber core region transmissive to optical energy of a signal wavelength and absorptive to optical energy of an excitation wavelength different from the signal wavelength, the first optical fiber comprising a concentration of dopant ions residing within the core region, the dopant ions being operable to absorb optical energy at the excitation wavelength,

a first source of optical energy of the excitation wavelength coupled into the first-fiber core region of the first optical fiber, and

a second source of optical energy of the signal wavelength coupled into the first-fiber core region of the first optical fiber;

thereafter

operating the first source of optical energy in a first state to cause the first optical fiber to absorb a first quantity of optical energy;

operating the second source of optical energy to transmit a first signal through the first optical fiber;

further operating the first source of optical energy in a second state to cause the first optical fiber to absorb a second quantity of optical energy; and

further operating the second source of optical energy to transmit a second signal through the first optical fiber.

20. The method of claim 19, wherein the optical fiber device further comprises

a second optical fiber.

21. The method of claim 20, wherein the second optical fiber comprises

a second-fiber core region having resident therein substantially the same concentration of the dopant ions as in the first-fiber core region of the first optical fiber.

22. The method of claim 20, wherein the first source of optical energy of the excitation wavelength is not coupled into the second optical fiber.

23. The method of claim 20, wherein a phase front of the first optical fiber is controlled to have a selected relationship to the phase front of the second optical fiber.

24. The method of claim 19, wherein the first optical fiber comprises one arm of an interferometer.

25. The method of claim 19, wherein the first optical fiber is a discrete optical fiber.

26. The method of claim 19, wherein the first optical fiber is a waveguide of an integrated optical waveguide.

27. The method of claim 19, wherein the first optical fiber has a first temperature in the first state, and a second temperature in the second state.

28. The method of claim 19, wherein the first optical fiber has a first index of refraction in the first state, and a second index of refraction in the second state.

29. The method of claim 19, wherein the first optical fiber has a first polarizability in the first state, and a second polarizability in the second state.

30. The method of claim 19, wherein the first optical fiber comprises an element of a fiber Bragg grating.

31. The method of claim 19, wherein the first optical fiber comprises an element of a coherent laser radar.

32. The method of claim 19, wherein the first optical fiber comprises an element of an optical fiber array.