Optical waveguides and grating structures fabricated using polymeric dielectric compositions

• US 20030039443A1
• Filed: 07/26/2002
• Published: 02/27/2003
• Est. Priority Date: 07/26/2001
• Status: Active Grant

• Current Assignee: Penn State Research Foundation
• Original Assignee: Penn State Research Foundation
• Inventors: Catchmark, Jeffrey M., Lavallee, Guy P.
• Granted Patent: US 6,826,333 B2
• Time in Patent Office: Days
• US Class Current: 385/37
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 2006/12097 Ridge, rib or the like
• CPC Class Codes: G02B 6/12004 Combinations of two or more optical elements
• CPC Class Codes: G02B 6/1221 made from organic materials
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G02B 6/124 Geodesic lenses or integrated gratings
• 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 6/4249 comprising arrays of active devices and fibres
• CPC Class Codes: G02F 1/0147 based on thermo-optic effects G02F1/132 takes precedence
• CPC Class Codes: G02F 1/065 in an optical waveguide structure
• CPC Class Codes: G02F 2201/30 grating

Abstract

Using polymeric dielectric materials (preferably materials derived from bisbenzocyclobutene monomers) and an electron beam lithography process for patterning this material, we have developed a process for fabricating optical waveguides with complex integrated devices such as gratings. Such gratings are not limited to one-dimensional type gratings but can include 2 dimensional gratings such as curved gratings or photonic crystals. Due to the properties of BCB, this process could also be implemented using optical photolithography depending upon the waveguide dimensions desired and the grating dimensions desired. Alternatively, the optical waveguide could be patterned using optical lithography and the grating can be patterned using electron beam lithography. Gratings with much more dimensional precision can be fabricated using electron beam lithography. Gratings fabricated with precise dimensional control are required, for example, for many applications including Dense Wavelength Division Multiplexing (DWDM) for telecommunications applications. In addition, the general process described below can be applied to the fabrication of complex lightwave circuits containing, for example, multiple optical waveguides, couplers/splitters, grating based filters and even more complex devices and structures. Many other variations on these devices and structures as well as other structures can be developed using this process as would be apparent to anyone skilled in the art.

Claims

1. A method of producing an optical device having integrated waveguide and grating structures comprising:

applying onto a cladding material an energy sensitive composition to produce an first energy sensitive coating on said cladding;

patternwise exposing said first energy sensitive coating with an energy source to produce a first coating having exposed and unexposed regions;

contacting a developer and said first coating having exposed and unexposed regions to selectively remove said unexposed regions to produce a first patterned layer;

curing said first patterned layer to produce a waveguide structure;

applying an energy sensitive composition onto said waveguide structure to produce a second energy sensitive coating;

patternwise exposing said second energy sensitive coating with an energy source to produce a second coating having exposed and unexposed regions;

contacting a developer and said second coating having exposed and unexposed regions to selectively remove said unexposed regions to produce a second patterned layer; and

curing said second patterned layer to produce a grating structure thereby producing an optical device having integrated waveguide and grating structures.

2. The method of claim 1, wherein said energy source is selected form the group consisting of electron beam energy and optical radiation.

3. The method of claim 1, wherein said cladding material has an index of refraction less than said energy sensitive composition.

4. The method of claim 3, wherein said cladding material is selected form the group of spin on glass and silicon dioxide.

5. The method of claim 1, wherein said cladding material is first applied to a substrate.

6. The method of claim 5, wherein said cladding material is applied to said substrate by plasma enhanced chemical vapor deposition.

7. The method of claim 5, wherein said substrate is selected form the group consisting of:

semiconductors glasses, plastics, polymers, metals, ceramics, insulators, organic materials, inorganic materials, and any combinations thereof.

8. The method of claim 5, wherein said substrate is ceramic and wherein BCB is applied to said ceramic prior to applying cladding material.

9. The method of claim 1, wherein said energy source is electron beam energy and said patterned layers are nano-scale patterned layers.

10. The method of claim 1, wherein said energy source is optical radiation and said patterned layers are micro-scale patterned layers or layers with dimensions in the range of about 150 nanometers to about 1 micron.

11. The method of claim 1, wherein said energy sensitive composition is selected form the group consisting of:

momomers, oligomers, and polymers and any combinations thereof.

12. The method of claim 1, wherein said energy sensitive composition is a dielectric composition.

13. The method of claim 1, wherein said energy sensitive composition is a dielectric polymer.

14. The method of claim 1, wherein said energy sensitive composition is electron beam or optical radiation curable, organic soluble mixture comprising at least one oligomerized cyclobutarene made from a cyclobutarene monomer bridged by oranopolysiloxane and at least one photosensitive agent in an amount sufficient to convert the mixture to a polymer insoluble in a development solvent upon exposing the mixture to electron beam or optical radition.

15. The method of claim 14, wherein said oganopolysiloxane is divinyltetramnethydisiloxane.

16. The method of claim 14, wherein said photosensitive agent is a poly(aryl azide).

17. The method of claim 16, wherein said photosensitive agent is 2,6-bis(4-azidobensylidene)-4-alkylcyclohexanone,

18. The method of claim 16, wherein said photosensitive agent is 2,6-bis(4-azidobenzylidene)-4-methylcyclohexanone.

19. The method of claim 14, wherein said mixture contains an antioxidant.

20. The method of claim 19, wherein said mixture contains an antioxidant derived form 1,2,dihydro-2,2,4-trimethyquinoline.

21. The method of claim 1, wherein said energy sensitive composition is bisbenzocyclobutene (BCB).

22. The method of claim 1, wherein said first energy sensitive coating is soft baked prior to patterwise exposing said first energy sensitive coating with an energy source.

23. The method of claim 1, wherein said second energy sensitive coating is soft baked prior to patterwise exposing said second energy sensitive coating with an energy source.

24. The method of claim 1, wherein said optical device has a plurality of waveguides.

25. The method of claim 1, wherein said optical device has a plurality of gratings.

26. An optical device having integrated waveguide and grating structures prepared by a method comprising:

applying onto a cladding material an energy sensitive composition to produce an first energy sensitive coating on said cladding;

patternwise exposing said first energy sensitive coating with an energy source to produce a first coating having exposed and unexposed regions;

contacting a developer and said first coating having exposed and unexposed regions to selectively remove said unexposed regions to produce a first patterned layer;

curing said first patterned layer to produce a waveguide structure;

applying an energy sensitive composition onto said waveguide structure to produce a second energy sensitive coating;

patternwise exposing said second energy sensitive coating with an energy source to produce a second coating having exposed and unexposed regions;

contacting a developer and said second coating having exposed and unexposed regions to selectively remove said unexposed regions to produce a second patterned layer; and

curing said second patterned layer to produce a grating structure thereby producing an optical device having integrated waveguide and grating structures.

27. The method of claim 26, wherein said energy source is selected form the group consisting of electron beam energy and optical radiation.

28. The method of claim 26, wherein said cladding material has an index of refraction less than said energy sensitive composition.

29. The method of claim 28, wherein said cladding material is selected form the group of spin on glass and silicon dioxide.

30. The method of claim 26, wherein said cladding material is first applied to a substrate.

31. The method of claim 30, wherein said cladding material is applied to said substrate by plasma enhanced chemical vapor deposition.

32. The method of claim 30, wherein said substrate is selected form the group consisting of:

semiconductors glasses, plastics, polymers, metals, ceramics, insulators, organic materials, inorganic materials, and any combinations thereof.

33. The method of claim 30, wherein said substrate is ceramic and wherein BCB is applied to said ceramic prior to applying cladding material.

34. The method of claim 26, wherein said energy source is electron beam energy and said patterned layers are nano-scale patterned layers.

35. The method of claim 26, wherein said energy source is optical radiation and said patterned layers are micro-scale patterned layers or layers with dimensions in the range of about 150 nanometers to about 1 micron.

36. The method of claim 26, wherein said energy sensitive composition is selected form the group consisting of:

momomers, oligomers, and polymers and any combinations thereof.

37. The method of claim 26, wherein said energy sensitive composition is a dielectric composition.

38. The method of claim 26, wherein said energy sensitive composition is a dielectric polymer.

39. The method of claim 26, wherein said energy sensitive composition is electron beam or optical radiation curable, organic soluble mixture comprising at least one oligomerized cyclobutarene made from a cyclobutarene monomer bridged by oranopolysiloxane and at least one photosensitive agent in an amount sufficient to convert the mixture to a polymer insoluble in a development solvent upon exposing the mixture to electron beam or optical radition.

40. The method of claim 39, wherein said oganopolysiloxane is divinyltetramethydisiloxane.

41. The method of claim 39, wherein said photosensitive agent is a poly(aryl azide).

42. The method of claim 41, wherein said photosensitive agent is 2,6-bis(4-azidobensylidene)-4-alkylcyclohexanone,

43. The method of claim 41, wherein said photosensitive agent is 2,6-bis(4-azidobenzylidene)-4-methylcyclohexanone.

44. The method of claim 39, wherein said mixture contains an antioxidant.

45. The method of claim 44, wherein said mixture contains an antioxidant derived form 1,2,dihydro-2,2,4-trimethyquinoline.

46. The method of claim 26, wherein said energy sensitive composition is bisbenzocyclobutene (BCB).

47. The method of claim 26, wherein said first energy sensitive coating is soft baked prior to patterwise exposing said first energy sensitive coating with an energy source.

48. The method of claim 26, wherein said second energy sensitive coating is soft baked prior to patterwise exposing said second energy sensitive coating with an energy source.

49. The method of claim 26, wherein said optical device has a plurality of waveguides.

50. The method of claim 26, wherein said optical device has a plurality of gratings.

51. An optical device comprising:

at least one BCB waveguide structure;

at least one BCB grating structure disposed on said at least one BCB waveguide structure;

cladding material on which said at least one waveguide structure is disposed; and

optionally

a substrate on which said cladding material is disposed, wherein at least one feature of said grating or waveguide is nano-scale.

52. The device of claim 51, wherein said cladding material has an index of refraction lessthan said at lest one BCB waveguide structure.

53. The device of claim 51, wherein said cladding material is selected form the group of spin on glass and silicon dioxide.

54. The deice of claim 51, wherein said substrate is selected form the group consisting of:

semiconductors glasses, plastics, polymers, metals, ceramics, insulators, organic materials, inorganic materials, and any combinations thereof.

55. The device of claim 51, wherein at least one feature of said waveguide is from 5 nanometers to 50 nanometers in size.

56. The device of claim 51, wherein at least one feature of said grating structure is from 5 nanometers to 50 nanometers in size.

57. The device of claim 51, wherein said device has a plurality of waveguide structures.

58. The device of claim 51, wherein said device has a plurality of grating structures.

59. The device of claim 51, further comprising at least one resistive element.

60. The device of claim 51, further comprising at least one metal contact.

61. The device of claim 51, wherein said substrate is low temperature co-fired ceramic.

62. The device of claim 61, wherein BCB is disposed on said low temperature co-fired ceramic substrate.

63. The device of claim 61, further comprising at least one optical fiber.

64. A tunable optical device having at least 1 integrated waveguide and grating structure comprising:

a substrate material containing one or more electrically contacted heat producing elements;

a cladding material disposed on said substrate;

at least one waveguide structure disposed on said cladding material;

at least one grating structure disposed on or near said waveguide structure;

wherein said waveguide structure and or said grating structure are in close proximity to said thermal element.

65. The device of claim 64 where said grating is composed of Bizbenzocyclobutane (BCB).

66. A tunable optical device having at least 1 integrated waveguide and grating structure comprising:

a substrate material containing one or more electrically contacted heat producing elements;

a planarizing material disposed on top of said heat producing elements;

a cladding material disposed on said planarizing material;

at least one waveguide structure disposed on said cladding material;

at least one grating structure disposed on or near said waveguide structure;

wherein said waveguide structure and or said grating structure are in close proximity to said thermal element.

67. The device of claim 66 where said planarizing material is bisbenzocyclobutene (BCB).

68. The device of claim 66 where said grating is composed of bisbenzocyclobutene (BCB).

69. A tunable optical device having at least one integrated waveguide and grating structure prepared by a method comprising:

fabricating an electrically contacted thermal element onto a substrate;

disposing a planarizing material onto said substrate;

disposing a cladding material onto said substrate;

applying onto a cladding material an energy sensitive composition to produce an first energy sensitive coating on said cladding;

patternwise exposing said first energy sensitive coating with an energy source to produce a first coating having exposed and unexposed regions;

contacting a developer and said first coating having exposed and unexposed regions to selectively remove said unexposed regions to produce a first patterned layer;

curing said first patterned layer to produce a waveguide structure;

applying an energy sensitive composition onto said waveguide structure to produce a second energy sensitive coating;

patternwise exposing said second energy sensitive coating with an energy source to produce a second coating having exposed and unexposed regions;

contacting a developer and said second coating having exposed and unexposed regions to selectively remove said unexposed regions to produce a second patterned layer; and

curing said second patterned layer to produce a grating structure thereby producing a tunable optical device having at least one integrated waveguide and grating structure.

70. The method of claim 69 where said planarizing material is Bizbenzoclclobutane (BCB).

71. The method of claim 69 where said second patterned layer is Bizbenzoclclobutane (BCB).