Tunable laser with microactuator

• US 20010036206A1
• Filed: 03/12/2001
• Published: 11/01/2001
• Est. Priority Date: 09/20/1999
• Status: Active Grant

• Current Assignee: Coherent Inc (Coherent Corp.)
• Original Assignee: iolon, Inc. (Coherent Corp.)
• Inventors: Jerman, John H., Heanue, John F., Berger, Jill D., Grade, John D.
• Granted Patent: US 6,847,661 B2
• Time in Patent Office: Days
• US Class Current: 372/20
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: H01S 5/02325 Mechanically integrated components on mount members or optical micro-benches
• CPC Class Codes: H01S 5/0654 Single longitudinal mode emission
• CPC Class Codes: H01S 5/0683 by monitoring the optical output parameters
• CPC Class Codes: H01S 5/0687 Stabilising the frequency of the laser
• CPC Class Codes: H01S 5/143 Littman-Metcalf configuration, e.g. laser - grating - mirror

Abstract

A tunable laser comprising a laser source for providing light with a wavelength along an optical path. A diffractive element is positioned in the optical path and spaced from the laser source for redirecting the light received from the laser source. A reflective element is positioned in the optical path and spaced from the diffractive element for receiving the light redirected by the diffractive element and for further redirecting the light back along the optical path to the reflective element. The diffractive element receives the light further redirected by the reflective element and returns the light along the optical path to the laser source. The optical path created by the laser source, the diffractive element and the reflective element causes the light to lase at the wavelength. At least one microactuator is coupled to one of the diffractive element and the reflective element for moving such element to select the wavelength of the light. A variety of microactuators that can be used with the tunable laser are provided.

Claims

1. A tunable laser comprising a laser source for providing light with a wavelength along an optical path, a diffractive element positioned in the optical path and spaced from the laser source for redirecting the light received from the laser source, a reflective element positioned in the optical path and spaced from the diffractive element for receiving the light redirected by the diffractive element and for further redirecting the light back along the optical path to the reflective element, the diffractive element receiving the light further redirected by the reflective element and returning the light along the optical path to the laser source whereby the optical path created by the laser source, the diffractive element and the reflective element causes the light to lase at the wavelength, and at least one microactuator coupled to one of the diffractive element and the reflective element for moving such element to select the wavelength of the light.

2. The tunable laser of

claim 1

wherein the optical path extends from the laser source to the diffractive element and then to the reflective element along an optical path length and wherein the wavelength has a half wavelength and can be selected from a range of wavelengths, the at least one microactuator moving said one of the diffractive element and the reflective element so that the optical path length equals an integer number of half wavelengths of the selected wavelength over the range of wavelengths.

3. The tunable laser of

claim 2

wherein the range of wavelengths extends from approximately 1520 nanometers to approximately 1560 nanometers.

4. The tunable laser of

claim 1

wherein the selected wavelength is 1540 nanometers.

5. The tunable laser of

claim 1

wherein the at least one microactuator includes a microactuator coupled to the reflective element for moving the reflective element.

6. The tunable laser of

claim 1

wherein the at least one microactuator includes a microactuator coupled to the reflective element for rotating the reflective element about a pivot point.

7. The tunable laser of

claim 6

wherein the pivot point is spaced apart from the microactuator.

8. The tunable laser of

claim 6

further comprising means carried by the substrate for translating the reflective element relative to the diffractive element.

9. The tunable laser of

claim 1

wherein the at least one microactuator includes a first microactuator coupled to the reflective element for rotating the reflective element about a pivot point and a second microactuator coupled to the reflective element for translating the reflective element relative to the diffractive element.

10. The tunable laser of

claim 1

wherein the at least one microactuator includes a micromachined actuator.

11. The tunable laser of

claim 1

wherein the at least one microactuator is an electrostatic microactuator having interdigitatable comb fingers.

12. The tunable laser of

claim 11

further comprising a controller for measuring the capacitance between the interdigitatable comb fingers and providing a drive signal to the at least one microactuator in response to the signal.

13. The tunable laser of

claim 1

further comprising a counterbalance carried by the substrate and coupled to the at least one microactuator and the one of the diffractive element and the reflective element for inhibiting undesirable movement of the one of the diffractive element and the reflective element in response to externally applied accelerations to the tunable laser.

14. The tunable laser of

claim 1

wherein the reflective element includes a retroreflector.

15. The tunable laser of

claim 1

wherein the laser source includes a Fabry-Perot laser.

16. The tunable laser of

claim 1

further comprising an optical sensor for sensing a light beam reflected from one of the diffractive element and the reflective element so as to measure the wavelength of the light and producing an error signal corresponding to any deviation between the measured wavelength and the selected wavelength and a controller electrically coupled to the optical sensor and the at least one microactuator for receiving the error signal and providing a control signal to the at least one microactuator in response to the error signal.

17. The tunable laser of

claim 16

wherein the optical sensor is a position sensing device.

18. The tunable laser or

claim 17

further comprising an additional laser source for supplying the light beam.

19. The tunable laser of

claim 17

wherein the light beam is supplied by the laser source.

20. The tunable laser of

claim 16

wherein the optical sensor is a wavelength locker.

21. The tunable laser of

claim 1

further comprising an optical sensor for sensing the light so as to measure the wavelength of the light and producing an error signal corresponding to any deviation between the measured wavelength and the selected wavelength and a controller electrically coupled to the optical sensor and the at least one microactuator for receiving the error signal and providing a control signal to the at least one microactuator in response to the error signal.

22. The tunable laser of

claim 21

wherein the optical sensor is selected from the group consisting of a position sensing device and a wavelength locker.

23. The tunable laser of

claim 1

further comprising a collimating lens disposed between the laser source and the diffractive element and an additional microactuator coupled to the collimating lens for moving the collimating lens to enhance the return of the light to the laser source.

24. The tunable laser of

claim 23

wherein the additional microactuator is an electrostatic microactuator.

25. The tunable laser of

claim 23

further comprising a counterbalance coupled to the collimating lens and the additional microactuator for inhibiting undesirable movement of the collimating lens in response to externally applied accelerations to the collimating lens.

26. The tunable laser of

claim 1

further comprising an electroabsorptive modulator disposed in the optical path.

27. The tunable laser of

claim 26

wherein the electroabsorptive modulator is disposed between the laser source and the diffractive element.

28. A tunable laser comprising a laser source for providing light with a wavelength along an optical path, a diffractive element positioned in the optical path and spaced from the laser source for redirecting the light received from the laser source, a reflective element positioned in the optical path and spaced from the diffractive element for receiving the light redirected by the diffractive element and for further redirecting the light back along the optical path to the reflective element, the diffractive element receiving the light further redirected by the reflective element and returning the light along the optical path to the laser source whereby the optical path created by the laser source, the diffractive element and the reflective element causes the light to lase at the wavelength, and micromechanical means coupled to one of the diffractive element and the reflective element for rotating and translating such element to select the wavelength of the light.

29. The tunable laser of

claim 28

wherein the micromechanical means includes a microactuator for rotating such element.

30. The tunable laser of

claim 29

wherein the micromechanical means includes an additional microactuator for translating such element.

31. A tunable laser comprising a laser source for providing light with a wavelength along an optical path, a diffractive element positioned in the optical path and spaced from the laser source for redirecting the light received from the laser source, a reflective element positioned in the optical path and spaced from the diffractive element for receiving the light redirected by the diffractive element and for further redirecting the light back along the optical path to the reflective element, the diffractive element receiving the light further redirected by the reflective element and returning the light along the optical path to the laser source whereby the optical path created by the laser source, the diffractive element and the reflective element causes the light to lase at the wavelength, a collimating lens disposed between the laser source and the diffractive element and a microactuator coupled to the collimating lens for moving the collimating lens to enhance the return of the light to the laser source.

32. The tunable laser of

claim 31

wherein the microactuator is an electrostatic microactuator.

33. The tunable laser of

claim 31

further comprising counterbalancing means coupled to the microactuator and to the collimating lens for inhibiting undesirable movement of the collimating lens in response to externally applied accelerations to the tunable laser.

34. The tunable laser of

claim 31

further comprising a power detector for monitoring the power of the light and a controller electrically coupled to the power detector and the microactuator for providing a control signal to the microactuator for moving the collimating lens to increase the power of the light.