Integrated optical micro-electromechanical systems and methods of fabricating and operating the same

• US 20020105699A1
• Filed: 02/02/2001
• Published: 08/08/2002
• Est. Priority Date: 02/02/2001
• Status: Active Grant

• Current Assignee: Teravicta Technologies Incorporated
• Original Assignee: Teravicta Technologies Incorporated
• Inventors: Hu, Kai, Reed, Jason D., Miracky, Robert F., Hilbert, Claude
• Granted Patent: US 6,636,653 B2
• Time in Patent Office: Days
• US Class Current: 398/56
• CPC Class Codes: G02B 6/1245 Geodesic lenses
• CPC Class Codes: G02B 6/32 having lens focusing means positioned between opposed fibre ends with lens being an integral part of the single fibre end G02B6/262
• CPC Class Codes: G02B 6/3524 the optical element being refractive
• 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 6/3584 constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: G02B 6/3588 of the processed beams, i.e. controlling during switching of orientation, alignment, or beam propagation properties such as intensity, size or shape
• CPC Class Codes: G02B 6/3598 Switching means directly located between an optoelectronic element and waveguides, including direct displacement of either the element or the waveguide, e.g. optical pulse generation based on changing the optical properties of the medium G02F1/00; optical pulse generation in optical transmitters H04B10/508; optical pulse generation by controlling laser operation H01S3/00
• 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 6/4232 using the surface tension of fluid solder to align the elements, e.g. solder bump techniques flip-chip mounting techniques in assembly of semiconductor devices H01L24/81
• CPC Class Codes: G02B 6/4249 comprising arrays of active devices and fibres
• CPC Class Codes: G02B 6/43 Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01039 Yttrium [Y]
• CPC Class Codes: H01S 3/101 Lasers provided with means to change the location from which, or the direction in which, laser radiation is emitted
• 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 5/0071 for beam steering, e.g. using a mirror outside the cavity to change the beam direction
• CPC Class Codes: H01S 5/02257 using windows, e.g. specially adapted for back-reflecting light to a detector inside the housing
• CPC Class Codes: H01S 5/02325 : Mechanically integrated components on mount members or optical micro-benches
• CPC Class Codes: H01S 5/183 : having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]

Abstract

An apparatus and method of fabricating and operating a micro-electromechanical systems (MEMS) integrated optical structure is disclosed. Micro-optics is integrated with MEMS actuators to provide a building block for a micro-optical communication device. Such micro-optical communication device may realize a variety of optical communication systems including optical interconnects, laser communications, or fiber optic switches. In accordance with one aspect of the present invention, a micro-optical element such as a micro-lens is advantageously integrated with an actuator such as MEMS comb drive actuator to form a MEMS lens assembly. The MEMS lens assembly is further coupled to an optical source which may provide a MEMS integrated micro-optical communication device. This integration substantially obviates the generally needed external or manual positioning of the micro-optical element to align a light beam or an optical signal being emitted from the optical source. The MEMS comb drive actuator, responsive to an actuation force, selectively positions the micro-optical element. By appropriately micro positioning a micro-optical element such as a micro-lens relative to an optical source, such as an input optical fiber or a laser diode, a focused light beam or an optical signal may be coupled to a respective optical fiber or a detector. In one embodiment, a commonly used flip chip module assembly technique may be adapted for bonding the MEMS lens assembly to a carrier substrate, which preferably receives the optical source. The carrier substrate is generally disposed on a host assembly. A flip chip based passive alignment of the MEMS lens assembly could be provided. Additionally, an active alignment of the light beam or optical signal with an optical detector may be provided, which can be maintained through a feedback loop.

Claims

1. An integrated optical apparatus, comprising:

a micro-electromechanical member; and

a substantially transmissive micro-optical element coupled to the micro-electromechanical member.

2. The apparatus of claim 1, said micro-electromechanical member comprising:

an actuator for operating said substantially transmissive micro-optical element to manipulate an optical output from an optical source disposed proximal to the micro-electromechanical member.

3. The apparatus of claim 1, said optical source being in a coaxial alignment with the substantially transmissive micro-optical element.

4. The apparatus of claim 1, said substantially transmissive micro-optical element comprising a micro-lens.

5. The apparatus of claim 1, said micro-electromechanical member is substantially coplanar to said substantially transmissive micro-optical element.

6. The apparatus of claim 2, said substantially transmissive micro-optical element collimating said optical output to form a light beam.

7. The apparatus of claim 6, said substantially transmissive micro-optical element steering the light beam in a first selected direction responsive to an actuator input applied to said actuator.

8. The apparatus of claim 7, said actuator selectively positioning the substantially transmissive micro-optical element in response to at least one actuating force for steering the focussed light beam in said first selected direction to form a steered light beam.

9. The apparatus of claim 8, wherein an actuating force profile determines said first selected direction and a position of the substantially transmissive micro-optical element.

10. The apparatus of claim 8, said at least one actuating force being an applied voltage bias.

11. The apparatus of claim 8, said actuator is a comb drive actuator formed on a substrate.

12. The apparatus of claim 11, the comb drive actuator comprising:

one or more fixed combs; and

one or more movable combs fixed to said substantially transmissive micro-optical element and being displaced in response to the at least one actuating force.

13. The apparatus of claim 12, the comb drive actuator further comprising:

at least one suspension member, each suspension member operably connected at a first end to the one or more movable combs and at a second end to the substrate, thereby suspending the one or more movable combs.

14. The apparatus of claim 8, wherein a spatial alignment of said steered light beam is controlled by the selective positioning of said substantially transmissive micro-optical element.

15. The apparatus of claim 8, wherein said selective positioning of said substantially transmissive micro-optical element is caused in a first displacement direction substantially coplanar to a major surface of said micro-electromechanical member in response to a first actuating force.

16. The apparatus of claim 8, wherein said selective positioning of said substantially transmissive micro-optical element is caused in a second displacement direction substantially coplanar to a major surface of said micro-electromechanical member in response to a second actuating force.

17. The apparatus of claim 8, wherein said selective positioning of said substantially transmissive micro-optical element is caused in a third displacement direction coplanar to a major surface of said micro-electromechanical member responsive to a concurrent application of a first type of said at least one actuating force and a second type of said at least one actuating force.

19. The method of claim 18, wherein forming said integrated optical apparatus includes:

releasing said micro-electromechanical optical assembly.

20. The method of claim 18, wherein forming said micro-electromechanical member includes:

forming a first structural material layer over a substrate;

forming a sacrificial material layer over the first structural material layer; and

forming a second structural material layer over the sacrificial material layer.

21. The method of claim 18, wherein forming said substantially transmissive micro-optical element includes:

forming an optically refractive material layer having a major surface to fill said aperture; and

processing said micro-electromechanical optical assembly for adapting the major surface of said optical material layer into a surface profile determined through at least one parameter.

22. The method of claim 18, wherein said micro-electromechanical member is formed on a substantially transparent substrate.

23. The method of claim 22, wherein said substantially transparent substrate is glass or quartz.

25. The method of claim 24, wherein forming said micro-electromechanical member includes:

forming a first structural material layer over a substrate;

forming a sacrificial material layer over the first structural material layer; and

forming a second structural material layer over the sacrificial material layer.

26. The method of claim 24, wherein forming said substantially transmissive micro-optical element includes:

forming an optically refractive material layer having a major surface; and

processing said micro-electromechanical optical assembly for adapting the major surface of said optical material layer into a surface profile determined through at least one parameter.

27. The method of claim 24, wherein said micro-electromechanical member is formed on a substantially transparent substrate.

29. The apparatus of claim 28, the micro-electromechanical assembly further comprising:

a comb drive actuator formed on a substrate to selectively position the transmissive micro-optical element in response to an actuating force applied to said comb drive actuator.

30. The apparatus of claim 28, the light beam is steered to provide a steered light beam for an active alignment, and the active alignment dynamically aligns the steered light beam in a selected direction responsive to the actuating force.

31. The apparatus of claim 28, wherein the micro-electromechanical assembly is formed on a transparent substrate.

32. The apparatus of claim 28, wherein the optical source is a laser diode.

33. The apparatus of claim 28, wherein the optical source is a fiber.

34. The apparatus of claim 28, wherein the optical source is a vertical cavity surface emitting laser diode.

35. The apparatus of claim 28, wherein the optical source is an edge emitting laser diode.

36. The apparatus of claim 28, wherein the transmissive micro-optical element is a micro-lens.

37. The apparatus of claim 36, wherein the micro-lens comprises photo-polymer.

38. The apparatus of claim 28, the optical source comprising:

an input fiber disposed in a fiber optical cross connect switch.

39. The apparatus of claim 38, the micro-electromechanical assembly performs switching of said light beam received at the input fiber to optically link said received light beam to a first output fiber of a plurality of output fibers disposed substantially facing said input fiber of the fiber optical cross connect switch.

40. The apparatus of claim 29, the comb drive actuator further comprising:

one or more fixed combs; and

one or more movable combs being displaced in response to the actuating force, said one or more movable combs including a frame to hold said transmissive micro-optical element and at least one suspension member, each suspension member operably connected at a first end to the frame and at a second end to the substrate, thereby suspending said one or more movable combs.

41. The apparatus of claim 30, wherein a feedback control loop maintains a spatial alignment of the steered light beam.

42. The apparatus of claim 31, the micro-electromechanical assembly comprises support layers.

43. The apparatus of claim 31, the transmissive micro-optical element is coplanar with a major surface of the micro-electromechanical assembly.

44. The apparatus of claim 40, the actuating force is an electrostatic force.

46. The apparatus of claim 45, the micro-electromechanical assembly further comprising:

a comb drive actuator formed on a substrate to selectively position the transmissive micro-optical elements in response to an actuating force applied to said comb drive actuator.

47. The apparatus of claim 45, wherein said light beams are steered to provide respective steered light beams for an active alignment, the active alignment dynamically aligns the respective steered light beams in a selected direction in response to the actuating force.

48. The apparatus of claim 45, wherein the micro-electromechanical assembly is formed on a transparent substrate.

49. The apparatus of claim 45, wherein the optical sources comprise a laser diode array.

50. The apparatus of claim 45, wherein the optical sources comprise a fiber array.

51. The apparatus of claim 45, wherein the optical sources comprise a vertical cavity surface emitting laser diode array.

52. The apparatus of claim 45, wherein the optical sources comprise an edge emitting laser diode array.

53. The apparatus of claim 45, wherein the transmissive micro-optical elements are micro-lenses.

54. The apparatus of claim 53, wherein the micro-lenses comprise a photo-polymer micro-lens array.

55. The apparatus of claim 45, wherein each said optical source comprises an input fiber disposed in a fiber optical cross connect switch.

56. The apparatus of claim 55, the micro-electromechanical assembly performs beam switching of the respective light beams received at the associated input fibers to optically link the received respective light beams to a corresponding output fiber of a plurality of output fibers disposed substantially facing said input fibers of the fiber optical cross connect switch.

57. The apparatus of claim 46, the comb drive actuator further comprising:

one or more fixed combs; and

one or more movable combs being displaced in response to the actuating force, wherein said one or more movable combs include a frame to hold said transmissive micro-optical elements and at least one suspension member, each suspension member attached at a first end to the frame and at a second end to the substrate, thereby suspending said one or more movable combs.

58. The apparatus of claim 47, wherein a spatial alignment for each of the steered light beams is maintained by a corresponding feedback control loop.

59. The apparatus of claim 48, wherein the micro-electromechanical assembly comprises support layers.

60. The apparatus of claim 48, wherein said transmissive micro-optical elements are coplanar with a major surface of the micro-electromechanical assembly.

61. The apparatus of claim 57, wherein the actuating force is an electrostatic force.

18. A method of fabricating an integrated optical apparatus, comprising:

forming a micro-electromechanical member having an aperture; and

forming a substantially transmissive micro-optical element interposed at the aperture to provide a micro-electromechanical optical assembly.

24. A method of fabricating an integrated optical apparatus, comprising:

forming a micro-electromechanical member having an aperture;

separately forming a substantially transmissive micro-optical element; and

assembling the micro-electromechanical member with the micro-optical element.

28. An optical communication apparatus, comprising:

an optical source to emit a light beam; and

a micro-electromechanical assembly coupled to the optical source and having a transmissive micro-optical element to receive the light beam for focusing and selective steering thereof.

45. An optical communication apparatus, comprising:

a plurality of optical sources, each of the optical sources emitting a lights beam; and

a micro-electromechanical assembly having a transmissive micro-optical element corresponding to each of the optical sources for focusing and steering respective light beams received at the corresponding transmissive micro-optical elements.

62. An optical communication apparatus, comprising:

an optical source to emit a light beam; and

a micro-electromechanical assembly, the micro-electromechanical assembly is formed on a transmissive substrate substantially parallel to a horizontal plane, the micro-electromechanical assembly including an electrostatic comb drive actuator having a micro-lens for focusing the light beam, said micro-electromechanical assembly being coupled to the optical source for selectively steering the light beam, the electrostatic comb drive actuator including;

one or more fixed combs each having a first set of fingers, and

one or more movable combs each having a second set of fingers in an interdigitized arrangement with the first set of fingers, the one or more movable combs being displaced within the horizontal plane in response to an actuating potential being applied to the electrostatic comb drive actuator, said one or more movable combs including a micro-lens frame holding said micro-lens and at least one suspension member, each suspension member attached at a first end to the micro-lens frame and at a second end to the transmissive substrate, thereby suspending the one or more movable combs substantially parallel to the horizontal plane.

63. An optical communication apparatus, comprising:

a plurality of optical sources, each of the optical sources emitting a light beam; and

a micro-electromechanical assembly, the micro-electromechanical assembly is formed on a transmissive substrate being substantially parallel to a horizontal plane, the micro-electromechanical assembly including an electrostatic comb drive actuator having an array of micro-lenses with each of the micro-lens corresponding to each of the optical sources for focusing the respective light beams, said micro-electromechanical assembly being coupled to said plurality of optical sources for steering the light beams, the electrostatic comb drive actuator including;

one or more fixed combs having a first set of fingers, and

one or more movable combs having a second set of fingers in an interdigitized arrangement with the first set of fingers, the one or more movable combs being displaced within the horizontal plane in response to an actuating potential being applied to the electrostatic comb drive actuator, said one or more movable combs including a micro-lens frame holding said array of micro-lenses and at least one suspension member, each suspension member attached at a first end to the micro-lens frame and at a second end to the transmissive substrate, thereby suspending the one or more movable combs substantially parallel to the horizontal plane.

64. An optical communication apparatus, comprising:

an optical source to emit a light beam;

a micro-electromechanical assembly coupled to the optical source and including a movable drive actuator having a transmissive micro-optical element for focusing and selectively steering the light beam; and

an optical signal sensing device for tracking the steered light beam, the optical signal sensing device providing a feedback signal to dynamically align the steered light beam.

65. An optical communication apparatus, comprising:

a plurality of optical sources, each of the optical sources emitting a light beam;

a micro-electromechanical assembly coupled to said plurality of optical sources and including a movable drive actuator having a transmissive micro-optical element corresponding to each of the optical sources for focusing and selectively steering the respective light beams; and

an optical signal sensing device corresponding to each of the optical sources for tracking the respective steered light beams, the optical signal sensing devices providing a feedback signal corresponding to each of the optical sources to dynamically align the respective steered light beams.

66. A method for optical communication, comprising:

receiving an optical input at a transmissive micro-optical element integrated with a micro-electromechanical assembly; and

positioning the transmissive micro-optical element to steer the optical input received at the transmissive micro-optical element in a first transmission direction in response to a first actuating force applied to the micro-electromechanical assembly for displacing the transmissive micro-optical element.

67. The method of claim 66, further comprising:

steering the optical input received at the transmissive micro-optical element in a second transmission direction in response to a second actuating force applied to the micro-electromechanical assembly.

68. The method of claim 66, wherein said first actuating force is a first voltage bias.

69. The method of claim 67, wherein said second actuating force is a second voltage bias.

70. A method for optical communication, comprising:

generating a light beam from an optical source, the light beam directed to a micro-lens integrated with a micro-electromechanical assembly;

deriving from passing the light beam through a first major surface of the micro-lens a focused light beam;

applying an actuating force to said micro-electromechanical assembly for displacing said micro-lens in a first direction within a horizontal plane to steer the focused light beam;

receiving from a second major surface of said micro-lens a steered light beam directed to an optical detector in response to the actuating force applied to the micro-electromechanical assembly, wherein the second major surface of said micro-lens is disposed opposite to said first major surface; and

coupling the steered light beam to said optical detector for providing an optical link through free space between the optical source and the optical detector.

71. A method for fabricating an integrated optical communication apparatus, comprising:

forming a micro-electromechanical member having an aperture;

forming a substantially transmissive micro-optical element interposed at the aperture to provide a micro-electromechanical optical assembly;

releasing said micro-electromechanical optical assembly; and

disposing an optical source proximal to said micro-electromechanical optical assembly.

72. The method of claim 71, wherein forming said micro-electromechanical member further comprising:

forming a first structural material layer over a substrate;

forming a sacrificial material layer over the first structural material layer;

forming a second structural material layer over the sacrificial material layer;

forming an optical polymer material layer having a major surface to fill said aperture; and

processing said micro-electromechanical optical assembly for adapting the major surface of said optical polymer material layer into a spherical profile determined through at least one parameter.

73. The method of claim 71, wherein said micro-electromechanical member is formed on a substantially transparent substrate.

74. The method of claim 73, wherein said substantially transparent substrate is glass.