Switching device and method of fabricating the same

• US 6,658,177 B1
• Filed: 07/19/2000
• Issued: 12/02/2003
• Est. Priority Date: 12/13/1999
• Status: Expired due to Fees

• Current Assignee: Memlink Ltd.
• Original Assignee: Memlink Ltd.
• Inventors: Chertkow, Igal Roberto
• Primary Examiner(s): NGO, HUNG NHAT
• Application Number:
  US09/619,014
• Time in Patent Office: 1,231 Days
• Field of Search: 385/16-20, 349/196, 349/197, 710/131
• US Class Current: 385/18
• CPC Class Codes: G02B 6/3514 the reflective optical element moving along a line so as to translate into and out of the beam path, i.e. across the beam path
• CPC Class Codes: G02B 6/3518 the reflective optical element being an intrinsic part of a MEMS device, i.e. fabricated together with the MEMS device MEMS devices in general B81B; manufacture of MEM devices in general B81C; micromechanical devices controlling the direction of light G02B26/0833
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/3572 Magnetic force magnetic forces controlling reflecting elements in general G02B26/085; magneto-optic devices G02F1/09
• CPC Class Codes: G02B 6/3576 Temperature or heat actuation thermal forces controlling reflecting elements in general G02B26/0866; thermo-optic devices G02F1/0147
• CPC Class Codes: G02B 6/3578 Piezoelectric force piezoelectric forces controlling reflecting elements in general G02B26/0858; piezo-optic devices G02F1/0131
• 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 6/423 using guiding surfaces for the alignment
• CPC Class Codes: H01H 2001/0084 with perpendicular movement of the movable contact relative to the substrate
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0026 using free space propagation (e.g. lenses, mirrors)
• CPC Class Codes: H04Q 2011/003 using switches based on microelectro-mechanical systems [MEMS]
• CPC Class Codes: H04Q 2011/0056 Clos

Abstract

A switching device that receives a plurality of input signals and provides a plurality of output signals has switches arranged in a two- or three-dimensional array configurations. At least two of the switches, which are preferably microelectromechanical or MEMS switches, reside on distinct physical substrate layers in the switching device, and at least one of the signals travels through a penetrable zone of one of the physical substrate layers. Three dimensional switching device blocks can be conveniently arranged in a Clos configuration or other switching configurations to reduce blocking and avoid rearrangement. The switching devices may be used to switch optical signals and may include mirrors as switching elements.

Claims

1. A switching device for receiving an input signal and providing the signal to a particular output signal path, the switching device comprising a plurality of physical substrate layers each having one or more switches thereon, and wherein the input signal travels through a penetrable zone of at least one of the physical substrate layers, and the input signal is an optical signal and the penetrable zone comprises an optically transparent material.

2. The switching device of claim 1 wherein the penetrable zone comprises an aperture in the physical substrate layer.

3. The switching device of claim 1 wherein each of the plurality of physical substrate layers are aligned in parallel with one another.

4. The switching device of claim 1 wherein the switches are microelectromechanical (MEMS) switches and each of the MEMS switches includes a switching element that is generally planar and disposed in parallel to the physical substrate layer on which the switching element resides.

5. The switching device of claim 1 wherein the switches are microelectromechanical (MEMS) switches and each of the MEMS switches includes a mirror having a reflective surface.

6. The switching device of claim 5 in which each mirror has opposing reflective surfaces.

7. The switching device of claim 1 wherein the MEMS switches are arranged in a two-dimensional array.

8. The switching device of claim 7 wherein the switching device receives a plurality of M input signals and provides a plurality of N output signals.

9. A The switching device of claim 8 wherein M equals N.

10. The switching device of claim 1 wherein the MEMS switches are arranged in a three-dimensional array comprising a plurality of similar two-dimensional arrays each of the two-dimensional arrays defining a logical layer of the device, and wherein the input signal travels in only one of the logical layers.

11. The switching device of claim 10 wherein each of the logical layers of the switching device receives a plurality of M input signals and provides a plurality of N output signals, the M input and N output signals travelling only in that logical layer.

12. The switching device of claim 11 wherein M equals N.

13. The switching device of claim 11 wherein the switching device has (M+N−

1) physical substrate layers.

14. The switching device of claim 11 wherein the switching device has max(M,N) physical substrate layers.

15. A switching device for receiving a plurality of M input signals and providing a plurality of N output signals each input signal being directed along a path into said device and each output signal being directed along a path out of said device said switching device comprising a plurality of switches arranged in a two-dimensional array, each of the switches being located at an intersection in which a projection of the path of one input signal meets a projection of the path of one output signal, wherein:

at least two of said switches reside on distinct physical substrate layers in the switching device, and at least one of said signals travels through a penetrable zone of one of the physical substrate layers; and

one switch is located at each intersection in which a projection of the path of one of the input signals meets a projection of the path of one of the output signals.

16. The switching device of claim 15 wherein each switch resides on one of the physical substrate layers near a penetrable zone of that physical substrate layer, so that in at least one operative position of the switch a signal input to or output by the switch passes through that penetrable zone.

17. The switching device of claim 16 wherein each switch includes a mirror, the mirror not affecting any signal input to the switch when in a first position and reflecting any signal input to the switch when in a second position.

18. The switching device of claim 17 wherein, for each of the switches, when the mirror is in the second position any signal input to the switch is angled at 45°

with respect to the mirror.

19. The switching device of claim 16 wherein each switch is a microelectromechanical (MEMS) switch.

20. The switching device of claim 19 wherein each MEMS switch comprises a generally planar switching element disposed in parallel to the surface of the physical substrate layer on which the switch resides and an actuator operatively;

engageable with the switching element for moving the switching element between different positions in a plane parallel to the surface of the physical substrate layer.

21. The switching device of claim 20 wherein the switching element of each MEMS switch comprises a mirror, the mirror not affecting any signal input to the switch when in a first position in said plane and reflecting any signal input to the switch when in a second position in said plane.

22. The switching device of claim 21 wherein, for each of the MEMS switches, any signal input to the switch is angled at 45°

with respect to the mirror.

23. The switching device of claim 15 wherein each input signal is denoted as an i'"'"'th input signal where i is an integer and 1≦

i≦

M and each output signal is denoted as a j'"'"'th output signal where j is an integer and 1≦

j≦

N, the path of the first input signal and the path of the first output signal being in closest proximity among the input and output signal paths, the path of the M'"'"'th input signal and the path of the N'"'"'th output signal being most distant among the input and output signal paths, the paths of any intermediately denoted input signals being located incrementally between the first and M'"'"'th input signal paths, and the paths of any intermediately denoted output signals being located incrementally between the first and N'"'"'th output signal paths, and wherein;

one switch in a first group of switches is located at each intersection in which a projection of the path of the i'"'"'th input signal meets a projection of the path of the j'"'"'th output signal for which the value of i+j for that intersection is less than or equal to max(M, N); and

one switch in a second group of switches is located at each intersection in which the path of the i'"'"'th input signal meets the path of the j'"'"'th output signal for which the value of i+j for that intersection equals max(M, N)+1.

24. The switching device of claim 23 wherein

each switch in the first group of switches resides on one of the physical substrate layers near a penetrable zone of that physical substrate layer, so that in at least one operative position of the switch a signal input to or output by the switch passes through that penetrable zone;

and

each switch in the second group of switches is located on the same physical layer and is static.

25. The switching device of claim 24 wherein

each switch in the first group includes a mirror having first and second reflective surfaces, wherein when the mirror is in a first position the mirror does not affect any signal input to the switch, and when the mirror is in a second position the mirror reflects any signal input to the switch;

and

each switch in the second group includes a static mirror that reflects any signal input to the switch.

26. The switching device of claim 25 wherein

for each of the switches in the first group, when the mirror thereof is in the first position any signal input to the switch is angled at 45°

with respect to said mirror; and

for each of the switches in the second group any signal input to the switch is angled at 45°

with respect to the mirror thereof.

27. The switching device of claim 24 wherein each switch in the first group is a microelectromechanical (MEMS) switch.

28. The switching device of claim 27 wherein each MEMS switch in the first group comprises a generally planar switching element disposed in parallel to the surface of the physical substrate layer on which the switch resides and an actuator operatively engageable with the switching element for moving the switching element between different positions in a plane parallel to the surface of the physical substrate layer.

29. The switching device of claim 28 wherein

the switching element of each MEMS switch in the first group comprises a mirror having first and second reflective surfaces, the mirror not affecting any signal input to the switch when in a first position in said plane and reflecting any signal input to the switch when in a second position in said plane;

and

each switch in the second group includes a static mirror parallel to the surface of the physical substrate layer on which the switch resides that reflects any signal input to the switch.

30. The switching device of claim 29 wherein for each of the MEMS switches, any signal input to the switch is angled at 45°

with respect to the mirror thereof.

31. The switching device of claim 15 further comprising a plurality of switches arranged in a three-dimensional array.

32. A three-dimensional switching device having a plurality of P logical switching layers, each of the logical layers receiving a plurality of M input signals and providing a plurality of N output signals, each input signal being directed along a path into said layer and each output signal being directed along a path out of said layer, each logical layer comprising:

a plurality of switches arranged in a two-dimensional array, each of the switches being located at an intersection in which a projection of the path of one input signal meets a projection of the path of one output signal, wherein;

at least two of said switches in each logical layer reside on distinct physical substrate layers in the switching device, and at least one of said signals travels through a penetrable zone of one of the physical substrate layers; and

the logical layers are parallel to one another within the switching device and, in each logical layer, one switch is located at each intersection in which a projection of the path of one of the input signals meets a projection of the path of one the output signals.

33. The switching device of claim 32 wherein each switch resides on one of the physical substrate layers near a penetrable zone of that physical substrate layer, so that in at least one operative position of the switch a signal input to or output by the switch passes through that penetrable zone.

34. The switching device of claim 33 wherein each switch includes a mirror, the mirror not affecting any signal input to the switch when in a first position and reflecting any signal input to the switch when in a second position.

35. The switching device of claim 34 wherein, for each of the switches, when the mirror is in the second position any signal input to the switch is angled at 45°

with respect to the mirror.

36. The switching device of claim 33 wherein each switch is a microelectromechanical (MEMS) switch.

37. The switching device of claim 36 wherein each MEMS switch comprises a generally planar switching element disposed in parallel to the surface of the physical substrate layer on which the switch resides and an actuator operatively engageable with the switching element for moving the switching element between different positions in a plane parallel to the surface of the physical substrate layer.

38. The switching device of claim 37 wherein the switching element of each MEMS switch comprises a mirror, the mirror not affecting any signal input to the switch when in a first position in said plane and reflecting any signal input to the switch when in a second position in said plane.

39. The switching device of claim 38 wherein, for each of the MEMS switches, any signal input to the switch is angled at 45°

with respect to the mirror.

40. The switching device of claim 32 wherein the logical layers are parallel to one another within the switching device and for each logical layer:

each input signal is denoted as an i'"'"'th input signal where i is an integer and 1≦

i≦

M and each output signal is denoted as a j'"'"'th output signal where j is an integer and 1≦

j≦

N, the path of the first input signal and the path of the first output signal being in closest proximity among the input and output signal paths, the path of the M'"'"'th input signal and the path of the N'"'"'th output signal being most distant among the input and output signal paths, the paths of any intermediately denoted input signals being located incrementally between the first and M'"'"'th input signal paths, and the paths of any intermediately denoted output signals being located incrementally between the first and N'"'"'th output signal paths;

one switch in a first group of switches is located at each intersection in which a projection of the path of the i'"'"'th input signal meets a projection of the path of the j'"'"'th output signal for which the value of i+j for that intersection is less than or equal to max(M, N); and

one switch in a second group of switches is located at each intersection in which the path of the i'"'"'th input signal meets the path of the j'"'"'th output signal for which the value of i+j for that intersection equals max(M, N)+1.

41. The switching device of claim 40 wherein for each logical layer:

each switch in the first group of switches resides on one of the physical substrate layers near a penetrable zone of that physical substrate layer, so that in at least one operative position of the switch a signal input to or output by the switch passes through that penetrable zone; and

each switch in the second group of switches is located on the same physical layer and is static.

42. The switching device of claim 41 wherein for each logical layer:

each switch in the first group includes a mirror having first and second reflective surfaces, wherein when the mirror is in a first position the mirror does not affect any signal input to the switch, and when the mirror is in a second position the mirror reflects any signal input to the switch; and

each switch in the second group includes a static mirror that reflects any signal input to the switch.

43. The switching device of claim 42 wherein

for each of the switches in the first group, when the mirror thereof is in the first position any signal input to the switch is angled at 45°

with respect to said mirror; and

for each of the switches in the second group any signal input to the switch is angled at 45°

with respect to the mirror thereof.

44. The switching device of claim 41 wherein each switch in the first group is a microelectromechanical (MEMS) switch.

45. The switching device of claim 44 wherein each MEMS switch in the first group comprises a generally planar switching element disposed in parallel to the surface of the physical substrate layer on which the switch resides and an actuator operatively engageable with the switching element for moving the switching element between different positions in a plane parallel to the surface of the physical substrate layer.

48. A switching configuration comprising

a first switching device as claimed in claim 32;

a second switching device as claimed in claim 32, wherein the number of logical layers in the second switching device equals the number of output signals in each logical layer of the first switching device, and wherein one and only one output from each logical layer of the first switching device is received as an input to a logical layer of the second switching device.

49. The switching configuration of claim 48 wherein the number of input and output signals in each logical layer of the second switching device equals the number of logical layers in the first switching device, within each switching device the logical layers are parallel to one another, and wherein the logical layers of the second switching device are positioned orthogonally with respect to the logical layers of the first switching device so that the paths of the output signals from the first switching device are colinear with the paths of the input signals of the second switching device.

50. A switching configuration comprising

a first switching device as claimed in claim 32;

a second switching device as claimed in claim 32, wherein the number of logical layers in the second switching device equals the number of output signals in each logical layer of the first switching device, and wherein one and only one output from each logical layer of the first switching device is received as an input to a logical layer of the second switching device; and

a third switching device as claimed in claim 32, wherein the number of logical layers in the third switching device equals the number of output signals in each logical layer of the second switching device, and wherein one and only one output from each logical layer of the second switching device is received as an input to a logical layer of the third switching device.

51. The switching configuration of claim 50 wherein the number of input and output signals in each logical layer of the second switching device equals the number of logical layers in the first switching device and the number of input and output signals in each logical layer of the third switching device equals the number of logical layers in the second switching device.

52. The switching configuration of claim 51 wherein within each switching device the logical layers are parallel to one another, and the logical layers of the second switching device are positioned orthogonally with respect to the logical layers of the first switching device so that the paths of the output signals from the first switching device are colinear with the paths of the input signals of the second switching device, and wherein the logical layers of the third switching device are positioned orthogonally with respect to the logical layers of the second switching device so that the paths of the output signals from the second switching device are colinear with the paths of the input signals of the third switching device.

53. The switching configuration of claim 52 wherein for each switching device:

in each logical layer, one switch is located at each intersection in which a projection of the path of one of the input signals meets a projection of the path of one of the output signals; and

each switch resides on one of the physical substrate layers near a penetrable zone of that physical substrate layer, so that in at least one operative position of the switch a signal input to or output by the switch passes through that penetrable zone.

54. The switching configuration of claim 53 wherein for each switching device:

each switch is a microelectromechanical (MEMS) switch comprising a mirror and the mirror of each MEMS switch is disposed in parallel to the surface of the physical substrate layer on which the switch resides and the switch further comprises an actuator operatively engageable with the switching element for moving the switching element between different positions in a plane parallel to the surface of the physical substrate layer.

55. The switching configuration of claim 52 wherein for each switching device:

in each logical layer, each input signal is denoted as an i'"'"'th input signal where i is an integer and 1≦

i≦

M and each output signal is denoted as a j'"'"'th output signal where j is an integer and 1≦

j≦

N, the path of the first input signal and the path of the first output signal being in closest proximity among the input and output signal paths, the path of the M'"'"'th input signal and the path of the N'"'"'th output signal being most distant among the input and output signal paths, the paths of any intermediately denoted input signals being located incrementally between the first and M'"'"'th input signal paths, and the paths of any intermediately denoted output signals being located incrementally between the first and N'"'"'th output signal paths;

in each logical layer, one switch in a first group of switches is located at each intersection in which a projection of the path of the i'"'"'th input signal meets a projection of the path of the j'"'"'th output signal for which the value of i+j for that intersection is less than or equal to max(M, N); and

in each logical layer, one switch in a second group of switches is located at each intersection in which the path of the i'"'"'th input signal meets the path of the j'"'"'th output signal for which the value of i+j for that intersection equals max(M, N)+1;

each switch in the first group of switches resides on one of the physical substrate layers near a penetrable zone of that physical substrate layer, so that in at least one operative position of the switch a signal input to or output by the switch passes through that penetrable zone; and

each switch in the second group of switches is located on the same physical layer and is static.

56. The switching configuration of claim 55 wherein for each switching device:

each switch in the first group is a microelectromechanical (MEMS) switch comprising a mirror and the mirror of each MEMS switch is disposed in parallel to the surface of the physical substrate layer on which the switch resides and the switch further comprises an actuator operatively engageable with the switching element for moving the switching element between different positions in a plane parallel to the surface of the physical substrate layer; and

each switch in the second group comprises a static mirror that is parallel to the surface of the physical substrate layer on which the switch resides.

57. A strictly non-blocking switching configuration comprising:

a first switching configuration as claimed in claim 53 wherein for the first switching device in the first switching configuration each logical layer includes a second path for each output signal out of the logical layer, said second paths of the output signals being colinear with the paths of the input signals in that layer; and

a second switching configuration as claimed in claim 53 wherein for the third switching device in the second switching configuration each logical layer includes a second path for each input signal into the logical layer, said second paths of the input signals being colinear with the paths of the output signals in that layer; and

wherein the first and second switching configurations are positioned such that the second paths of the output signals from the first switching device of the first switching configuration are colinear with the paths of the input signals of the first switching device of the second switching configuration, and the paths of the output signals from the third switching device of the first switching configuration are colinear with the second paths of the input signals of the third switching device of the second switching configuration.

58. A method of fabricating the switching device of claim 34 comprising:

fabricating the plurality of MEMS switches on a main substrate surface, the plurality of MEMS switches being arranged in P rows, the number of rows corresponding to the number of logical layers in the switching device, the plurality of MEMS switches on the main substrate surface being further divided into a plurality of sets of columns, the columns in each set being uniformly spaced and each set of columns being separated from an adjacent column by a space equaling that of a single column, each set of switches corresponding to the switches residing one of the physical substrate layers;

separating the sets on the main substrate surface into the plurality of physical substrate layers;

aligning the separated physical substrate layers to form the logical layers of the switching device; and

bonding the physical substrate layers together.

59. The method of claim 58 wherein M equals N for each logical layer.

60. The method of claim 59 wherein the switching device comprises 2M-1 physical substrate layers and, with each set denoted as an a'"'"'th set where a is an integer and 1≦

a≦

2M−

1, the number of columns of switches in the a'"'"'th set is equal to (M−

|M−

a|).

61. The method of claim 59 wherein the switching device comprises M physical substrate layers and, with each set denoted as an a'"'"'th set where a is an integer and 1≦

a≦

2M−

1, the number of columns of switches in the a'"'"'th set is equal to a.

46. The switching device of claim wherein

the switching element of each MEMS switch in the first group comprises a mirror having first and second reflective surfaces, the mirror not affecting any signal input to the switch when in a first position in said plane and reflecting any signal input to the switch when in a second position in said plane;

and

each switch in the second group includes a static mirror parallel to the surface of the physical substrate layer on which the switch resides that reflects any signal input to the switch.

47. The switching device of claim 46 wherein for each of the MEMS switches in the first group and each switch in the second group, any signal input to the switch is angled at 45°

with respect to the mirror thereof.

62. An optical device comprising:

a first diffracting reflection grating having a plurality of diffraction elements on one side thereof;

a second diffracting reflection grating having a plurality of diffraction elements on one side thereof,

wherein the first and second diffracting reflection gratings are positioned in parallel with one another, separated by a distance w, so that the side of the first diffracting reflection grating having the diffraction elements opposes the side of the second diffracting reflection grating having the diffraction elements.

63. A method of wavelength division demultiplexing (WDM) using the optical device of claim 62 as a demultiplexer, comprising:

directing a WDM signal at an initial input angle of incidence on to the diffraction elements of the first diffracting reflection grating so that the WDM signal is separated into a plurality of component wavelength signals each of which is reflected, at different angles, by the first diffracting reflection grating onto the diffraction elements of the second diffracting reflection grating and thereafter further reflected by the second diffracting reflection grating so that the plurality of component wavelength signals are output by the optical device in parallel and uniformly spaced from one another.

64. The method of claim 63 further comprising selecting the input angle of incidence and the distance w to provide a desired spacing of the component wavelength signals.

65. A method of wavelength division multiplexing (WDM) using the optical device of claim 62 as a multiplexer, comprising:

directing a plurality of parallel and uniformly spaced component wavelength signals at a common initial input angle of incidence on to the diffraction elements of the first diffracting reflection grating so that each component wavelength signal is reflected, at different angles, by the first diffracting reflection grating onto the diffraction elements of the second diffracting reflection grating and thereafter further reflected by the second diffracting reflection grating into a single WDM signal.

66. The method of claim 65 further comprising selecting the input angle of incidence and the distance w to accommodate a particular spacing of the component wavelength signals.

67. A switching device comprising:

a first set of inputs for receiving a plurality of inputs signals;

a second set of inputs;

a third set of inputs;

a first set of outputs for providing a plurality of output signals; and

a second set of outputs, wherein a signal provided at one of the second set of outputs is directed to a splitter which divides said signal into a first split signal and a second split signal, the first split signal being directed to an input in the second set of inputs and the second split signal being directed to an input in the third set of inputs.

68. A method of multicasting a multicast signal received at one of the first set of inputs in the switching device of claim 67 comprising:

(a) directing the multicast signal to one of the second set of outputs so that the multicast signal is received at one of the second set of inputs and at one of the third set of inputs;

(b) directing the multicast signal received at at least one of said one of the second set of inputs and said one of the third set of inputs to another of the second set of outputs so that the multicast signal is received at another of the second set of inputs and at another of the third set of inputs; and

(c) repeating steps (a) and (b) until the desired number of multicast signals are received at inputs of said second and third sets of inputs.