Tunable distributed feedback laser

• US 6,754,243 B2
• Filed: 08/09/2001
• Issued: 06/22/2004
• Est. Priority Date: 08/09/2000
• Status: Expired due to Term

• Current Assignee: Lumentum Operations, LLC (Lumentum Holdings Inc.)
• Original Assignee: JDS Uniphase Corporation (Lumentum Holdings Inc.)
• Inventors: Pezeshki, Bardia, Lang, Robert J., Missey, Mark
• Primary Examiner(s): LEUNG, QUYEN PHAN
• Application Number:
  US09/925,963
• Publication Number:
  US 20020064192A1
• Time in Patent Office: 1,048 Days
• Field of Search: 372/50, 372/102, 372/23, 372/92, 372/20, 372/96, 359/291
• US Class Current: 372/20
• CPC Class Codes: G02B 2006/12104 Mirror; Reflectors or the like
• CPC Class Codes: G02B 26/0816 by means of one or more reflecting elements
• CPC Class Codes: G02B 26/0875 by means of one or more refracting elements
• CPC Class Codes: G02B 6/3526 the optical element being a lens
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/4204 the coupling comprising intermediate optical elements, e.g. lenses, holograms encapsulated active devices H01S5/02208, H01L33/52
• CPC Class Codes: G02B 6/4209 Optical features
• CPC Class Codes: G02B 6/4214 the intermediate optical element having redirecting reflective means, e.g. mirrors, prisms for deflecting the radiation from horizontal to down- or upward direction toward a device G02B6/4246 takes precedence
• CPC Class Codes: G02B 6/4226 Positioning means for moving the elements into alignment, e.g. alignment screws, deformation of the mount
• CPC Class Codes: G02B 6/4249 comprising arrays of active devices and fibres
• CPC Class Codes: G02B 6/425 Optical features semiconductor laser arrays H01S5/40; hybrid LED arrays H01L25/0753; monolithic LED arrays H01L27/153
• CPC Class Codes: H01S 5/005 Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping H01S5/026, H01S5/18388 take precedence
• CPC Class Codes: H01S 5/02251 using optical fibres
• CPC Class Codes: H01S 5/0612 controlled by temperature
• CPC Class Codes: H01S 5/0687 Stabilising the frequency of the laser
• CPC Class Codes: H01S 5/12 the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers comprising a photonic bandgap structure H01S5/11; surface-emitting lasers H01S5/18
• CPC Class Codes: H01S 5/4012 Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
• CPC Class Codes: H01S 5/4031 Edge-emitting structures
• CPC Class Codes: H01S 5/4087 emitting more than one wavelength

Abstract

A wavelength tunable laser includes a distributed feedback (DFB) array with first and second DFB laser diodes that generate first and second beams of light in first and second wavelength ranges. A microelectromechanical (MEMS) optical element selectively couples one of the first and second beams of light from the DFB laser array into an optical waveguide. The MEMS optical element includes a collimating lens and a thermal or electrostatic MEMS actuator for moving the collimating lens to select the one of the first and second beams of light. A focusing lens is located between the collimating lens and the optical waveguide. Alternately, the MEMS optical element includes a fixed collimating lens that collimates the first and second beams of light, a mirror, and a MEMS actuator for tilting the mirror to select the one of the first and second beams of light.

Claims

1. A wavelength tunable laser comprising:

a distributed feedback (DFB) laser array including a first DFB laser diode that generates a first beam of light in a first wavelength range and a second DFB laser diode that generates a second beam of light in a second wavelength range;

an optical waveguide; and

a microelectromechanical (MEMS) optical element adjustable to selectively couple one of said first and second beams of light from said DFB laser array into said optical waveguide.

2. The wavelength tunable laser of claim 1 wherein said MEMS optical element includes:

a collimating lens; and

a MEMS actuator that adjusts a position of said collimating lens to select said one of said first and second beams of light.

3. The wavelength tunable laser of claim 2 wherein said MEMS actuator moves in one plane.

4. The wavelength tunable laser of claim 2 wherein said MEMS actuator includes an electrostatic actuator.

5. The wavelength tunable laser of claim 2 wherein said MEMS actuator includes a thermal actuator.

6. The wavelength tunable laser of claim 2 further comprising a focusing lens that is optically positioned between said collimating lens and said optical waveguide.

7. The wavelength tunable laser of claim 1 wherein said optical waveguide includes optical fiber suitable for telecommunications.

8. The wavelength tunable laser of claim 2 wherein said collimating lens and said MEMS actuator are fabricated using bulk silicon.

9. The wavelength tunable laser of claim 4 further comprising:

an electrostatic comb drive structure;

a flexible spring structure; and

a drive circuit that actuates said electrostatic comb drive structure and said flexible spring structure to adjust said position of said collimating lens.

10. The wavelength tunable laser of claim 5 further comprising:

a thermal actuating structure; and

a drive circuit that provides power to said thermal actuating structure to adjust said position of said collimating lens.

11. The wavelength tunable laser of claim 1 wherein said DFB laser array is temperature tunable.

12. The wavelength tunable laser of claim 11 further comprising:

a beam splitter that reflects a first portion of said one of said first and second beams of light and that passes a second portion of said one of said first and second beams of light;

a wavelength locker that receives one of said first and second portions from said beam splitter and that generates a wavelength error signal; and

a thermoelectric cooler that adjusts a temperature of said DFB laser array to vary a wavelength output by said DFB laser array based on said wavelength error signal.

13. The wavelength tunable laser of claim 1 further comprising a third DFB laser diode that generates a third beam of light in a third wavelength range, wherein said third wavelength range overlaps at least one of said first and second wavelength ranges.

14. The wavelength tunable laser of claim 1 further comprising a field lens that is located between said DFB laser array and said MEMS optical element, wherein said field lens removes vignetting effects.

15. The wavelength tunable laser of claim 2 wherein said first and second laser diodes, said collimating lens and said MEMS actuator are packaged on a common substrate.

16. The wavelength tunable laser of claim 1 wherein said first and second wavelength ranges are adjacent wavelength ranges.

17. The wavelength tunable laser of claim 1 further comprising an optical isolator that is located between said MEMS optical element and said optical waveguide.

18. The wavelength tunable laser of claim 1 further comprising an amplitude modulator that is located between said MEMS optical element and said optical waveguide.

19. The wavelength tunable laser of claim 1 wherein said MEMS optical element comprises:

a mirror; and

a MEMS actuator for tilting said mirror to select said one of said first and second beams of light.

20. The wavelength tunable laser of claim 19 wherein said MEMS actuator includes thermal actuators for tilting said movable mirror.

21. The wavelength tunable laser of claim 19 wherein said MEMS actuator includes electrostatic actuators for tilting said movable mirror.

22. The wavelength tunable laser of claim 19 further comprising:

a collimating lens that collimates said first and second beams of light; and

a focusing lens that focuses said one of said first and second beams of light reflected by said mirror into said optical waveguide.

23. The wavelength tunable laser of claim 22 further comprising a second mirror that is optically located between said mirror and said focusing lens.

24. The wavelength tunable laser of claim 22 wherein said mirror tilts in first and second axial directions to compensate for misalignment of said collimating lens and said first and second laser diodes relative to an alignment axis.

25. The wavelength tunable laser of claim 22 further comprising an optical isolator that is located between said focusing lens and said mirror.

26. The wavelength tunable laser of claim 22 further comprising an amplitude modulator that is located between said focusing lens and said optical waveguide.

27. A method for providing a beam of laser light having a tunable wavelength, comprising the steps of:

packaging a first DFB laser diode that generates a first beam of light in a first wavelength range and a second DFB laser diode that generates a second beam of light in a second wavelength range in a distributed feedback (DFB) array;

positioning a microelectromechanical (MEMS) optical element between said DFB laser array and an optical waveguide; and

selectively coupling one of said first and second beams of light from said DFB laser array into said optical waveguide.

28. The method of claim 27 further comprising the step of collimating said first and second beams of light.

29. The method of claim 28 further comprising the step of adjusting a position of said collimating lens with a MEMS actuator to select said one of said first and second beams of light.

30. The method of claim 29 wherein said MEMS actuator moves in one plane.

31. The method of claim 29 wherein said MEMS actuator is an electrostatic actuator.

32. The method of claim 29 wherein said MEMS actuator is a thermal actuator.

33. The method of claim 27 further comprising the step of positioning a focusing lens between said DFB laser array and said optical waveguide.

34. The method of claim 27 wherein said optical waveguide includes optical fiber.

35. The method of claim 29 further comprising the step of fabricating said collimating lens and said MEMS actuator from bulk silicon.

36. The method of claim 31 further comprising the step of actuating an electrostatic comb drive structure and a flexible spring structure to adjust said position of said collimating lens.

37. The method of claim 32 further comprising the step of actuating a thermal comb drive structure to adjust said position of said collimating lens.

38. The method of claim 27 further comprising the step of tuning a wavelength output by said DFB laser array by varying a temperature of said DFB laser array.

39. The method of claim 38 further comprising the steps of:

splitting said one of said first and second beams of light from said MEMS optical element into a first portion that is reflected by a beam splitter and a second portion that is passed by said beam splitter;

generating a wavelength error signal from one of said first and second portions; and

temperature tuning said DFB laser array based on said wavelength error signal.

40. The method of claim 27 further comprising the step of packaging a third DFB laser diode in said DFB laser array that generates a third beam of light in a third wavelength range, wherein said third wavelength range overlaps at least one of said first and second wavelength ranges.

41. The method of claim 27 further comprising the step of removing vignetting effects by positioning a field lens between said DFB laser array and said MEMS optical element.

42. The method of claim 29 further comprising the step of packaging said first and second laser diodes, said collimating lens and said MEMS actuator on a common substrate.

43. The method of claim 27 wherein said first and second wavelength ranges are adjacent wavelength ranges.

44. The method of claim 27 further comprising the steps of providing a optical isolator between said DFB laser array and said optical waveguide.

45. The method of claim 27 further comprising the step of providing an amplitude modulator between said DFB laser array and said optical waveguide.

46. The method of claim 27 further comprising the step of tilting a mirror using a MEMS actuator to select one of said first and second beams of light.

47. The method of claim 46 further comprising the step of tilting said mirror using an electrostatic actuator.

48. The method of claim 46 further comprising the step of tilting said mirror using a thermal actuator.

49. The method of claim 46 further comprising the step of optically positioning a second mirror between said mirror and said optical waveguide.

50. The method of claim 46 further comprising the step of tilting said mirror in first and second axial directions to compensate for misalignment.

51. The method of claim 46 further comprising the step of positioning an optical isolator between said mirror and said optical waveguide.

52. A wavelength tunable laser comprising:

a distributed feedback (DFB) array including a first DFB laser diode that generates a first beam of light in a first wavelength range and a second DFB laser diode that generates a second beam of light in a second wavelength range;

an optical waveguide;

a collimating lens; and

a MEMS actuator for adjusting a position of said collimating lens to selectively couple one of said first and second beams of light from said DFB laser array into said optical waveguide.

53. The wavelength tunable laser of claim 52 wherein said MEMS actuator moves in one plane.

54. The wavelength tunable laser of claim 52 wherein said MEMS actuator includes an electrostatic actuator.

55. The wavelength tunable laser of claim 52 wherein said MEMS actuator includes a thermal actuator.

56. The wavelength tunable laser of claim 52 further comprising a focusing lens that is located between said collimating lens and said optical waveguide.

57. The wavelength tunable laser of claim 52 wherein said optical waveguide includes optical fiber suitable for telecommunications.

58. The wavelength tunable laser of claim 54 wherein said MEMS actuator further comprises:

an electrostatic comb drive structure; and

a flexible spring structure.

59. The wavelength tunable laser of claim 55 wherein said MEMS actuator further comprises a thermal comb drive structure.

60. The wavelength tunable laser of claim 52 wherein said DFB laser array is temperature tunable.

61. The wavelength tunable laser of claim 60 further comprising:

a beam splitter that reflects a first portion of said one of said first and second beams of light and that passes a second portion of said one of said first and second beams of light;

a wavelength locker that receives one of said first and second portions from said beam splitter and that generates a wavelength error signal; and

a thermoelectric cooler that adjusts a temperature of said DFB laser array to vary a wavelength output by said DFB laser array based on said wavelength error signal.

62. The wavelength tunable laser of claim 52 further comprising a third DFB laser diode that generates a third beam of light in a third wavelength range, wherein said third wavelength range overlaps one of said first and second wavelength ranges.

63. The wavelength tunable laser of claim 52 further comprising a field lens that is located between said DFB laser array and said collimating lens, wherein said field lens removes vignetting effects.

64. The wavelength tunable laser of claim 52 wherein said first and second wavelength ranges are adjacent wavelength ranges.

65. The wavelength tunable laser of claim 52 further comprising a optical isolator that is located between said DFB laser array and said optical waveguide.

66. The wavelength tunable laser of claim 52 further comprising an amplitude modulator that is located between said DFB laser array and said optical waveguide.

67. A method for providing a beam of laser light having a tunable wavelength, comprising the steps of:

providing a distributed feedback (DFB) array;

generating a first beam of light in a first wavelength range using a first DFB laser diode of said DFB laser array;

generating a second beam of light in a second wavelength range using a second DFB laser diode of said DFB laser array;

positioning a collimating lens adjacent to said DFB laser array; and

selectively coupling one of said first and second beams of light from said DFB laser array into said optical waveguide using a MEMS actuator that adjusts a position of said collimating lens.

68. The method of claim 67 wherein said MEMS actuator includes an electrostatic actuator.

69. The method of claim 67 wherein said MEMS actuator includes a thermal actuator.

70. The method of claim 67 further comprising the step of positioning a focusing lens between said collimating lens and said optical waveguide.

71. The method of claim 67 wherein said optical waveguide is optical fiber suitable for telecommunications.

72. The method of claim 68 further comprising the step of actuating an electrostatic comb drive structure and a flexible spring structure to adjust said position of said collimating lens.

73. The method of claim 69 further comprising the step of actuating a thermal comb drive structure to adjust said position of said collimating lens.

74. The method of claim 67 further comprising the step of tuning a wavelength of said DFB laser array by varying a temperature of said DFB laser array.

75. The method of claim 74 further comprising the steps of:

reflecting a first portion of said one of said first and second beams of light using a beam splitter;

passing a second portion of said one of said first and second beams of light using said beam splitter;

generating a wavelength error signal from one of said first and second portions; and

adjusting a temperature of said DFB laser array using said wavelength error signal to vary said wavelength output by said DFB laser array.

76. The method of claim 67 further comprising the step of packaging a third DFB laser diode that generates a third beam of light in a third wavelength range in said DFB laser array, wherein said third wavelength range overlaps one of said first and second wavelength ranges.

77. The method of claim 67 further comprising the step of removing vignetting effects using a field lens that is located between said DFB laser array and said collimating lens.

78. The method of claim 67 wherein said first and second wavelength ranges are adjacent wavelength ranges.

79. The method of claim 67 further comprising the step of locating a optical isolator between said DFB laser array and said optical waveguide.

80. The method of claim 70 further comprising the step of locating an amplitude modulator between said focusing lens and said optical waveguide.

81. A wavelength tunable laser comprising:

a distributed feedback (DFB) array including a first DFB laser diode that generates a first beam of light in a first wavelength range and a second DFB laser diode that generates a second beam of light in a second wavelength range;

an optical waveguide;

a collimating lens that collimates said first and second beams of light;

a mirror; and

a MEMS actuator for tilting said mirror to selectively couple one of said first and second beams of light from said DFB laser array into said optical waveguide.

82. The wavelength tunable laser of claim 81 wherein said MEMS actuator includes thermal actuators for tilting said mirror.

83. The wavelength tunable laser of claim 81 wherein said MEMS actuator includes electrostatic actuators for tilting said mirror.

84. The wavelength tunable laser of claim 81 further comprising a focusing lens that is located between said mirror and said optical waveguide and that focuses said one of said first and second beams of light reflected by said mirror into said optical waveguide.

85. The wavelength tunable laser of claim 84 further comprising a second mirror that is optically located between said mirror and said focusing lens.

86. The wavelength tunable laser of claim 81 wherein said mirror tilts in first and second axial directions to compensate for misalignment.

87. The wavelength tunable laser of claim 81 further comprising an optical isolator that is located between said DFB laser array and said mirror.

88. A method for providing a beam of laser light having a tunable wavelength, comprising the steps of:

providing a distributed feedback (DFB) array;

generating a first beam of light in a first wavelength range using a first DFB laser diode of said DFB laser array;

generating a second beam of light in a second wavelength range using a second DFB laser diode of said DFB laser array;

collimating at least one of said first and second beams of light; and

tilting mirror using a MEMS actuator to selectively couple one of said first and second beams of light from said DFB laser array into an optical waveguide.

89. The method of claim 88 wherein said MEMS actuator includes thermal actuators for tilting said mirror.

90. The method of claim 88 wherein said MEMS actuator includes electrostatic actuators for tilting said mirror.

91. The method of claim 88 further comprising the step of focusing said one of said first and second beams of light reflected by said mirror into said optical waveguide.

92. The method of claim 91 further comprising the step of optically positioning a second mirror between said mirror and said optical waveguide.

93. The method of claim 88 wherein said mirror tilts in first and second axial directions to compensate for misalignment.

94. The method of claim 88 further comprising the step of locating an optical isolator between said DFB laser array and said mirror.

95. A telecommunications laser package adapted to couple an optical signal having a predetermined wavelength selected from a plurality of predetermined wavelengths into an optical waveguide comprising:

a plurality of DFB lasers formed in an array, at least two of the DFB lasers generating an optical signal having substantially different wavelengths; and

a collimating lens mounted in a microelectromechanical structure (MEMS) moveable to couple light emitted from any one of the DFB lasers along a path calculated to enter the optical waveguide.

96. The telecommunications package of claim 95 wherein at any given time the collimating lens couples light emitted from only one of the DFB lasers along a path calculated to enter the optical waveguide.

97. The telecommunications package of claim 96 wherein the optical waveguide is an optical fiber.

98. A telecommunications laser package adapted to couple an optical signal having a predetermined wavelength selected from a plurality of predetermined wavelengths into an optical waveguide comprising:

a plurality of DEB lasers formed in an array, at least two of the DFB lasers generating an optical signal having substantially different wavelengths; and

a microelectromechanical structure (MEMS) mirror moveable to reflect light emitted from any one of the DFB lasers along a path calculated to enter the optical waveguide.

99. The telecommunications package of claim 98 wherein the MEMS mirror reflects light emitted from only one of the DFB lasers along a path calculated to enter the optical waveguide.

100. The telecommunications package of claim 99 wherein the optical waveguide is an optical fiber.

101. A telecommunication network including a tunable laser system, the tunable laser system providing an optical signal transmitting information over a fiber optic line, the optical signal being of a wavelength selected from a plurality of predetermined wavelengths, the tunable laser comprising:

an array of distributed feedback (DFB) lasers, each of the DFB lasers emitting light in a predetermined wavelength range, at least some of the DFB lasers emitting light in different wavelength ranges, a collimating lens, and a MEMS actuator coupled to the collimating lens so as to position the collimating lens to couple light from any one of the DFB lasers on a path expected to result in transmission of the light on the fiber optic line.

102. A telecommunication network including a tunable laser system, the tunable laser system providing an optical signal transmitting information over a fiber optic line, the optical signal being of a wavelength selected from a plurality of predetermined wavelengths, the tunable laser comprising:

an array of distributed feedback (DFB) lasers, each of the DFB lasers emitting light in a predetermined wavelength range, at least some of the DFB lasers emitting light in different wavelength ranges, a MEMS mirror moveable so as to couple light from any one of the DEB lasers on a path expected to result in transmission of the light on the fiber optic line.