Miniature monolithic optical add-drop multiplexer

• US 6,453,087 B2
• Filed: 04/18/2001
• Issued: 09/17/2002
• Est. Priority Date: 04/28/2000
• Status: Expired due to Term

• Current Assignee: Auxora
• Original Assignee: Confluent Photonics Corp.
• Inventors: Davis, Steven J., Frish, Michael B., Kessler, William J., Keating, Philip B.
• Primary Examiner(s): Palmer, Phan T. H.
• Application Number:
  US09/837,339
• Publication Number:
  US 20010031113A1
• Time in Patent Office: 517 Days
• Field of Search: 385/15, 385/16, 385/18, 385/24, 385/27, 385/28, 385/31, 385/33, 385/37, 385/10, 359/124, 359/125, 359/128, 359/130, 359/133, 359/131
• US Class Current: 385/24
• CPC Class Codes: G02B 2006/12107 Grating
• CPC Class Codes: G02B 2006/12109 Filter
• CPC Class Codes: G02B 2006/12114 Prism
• CPC Class Codes: G02B 2006/12164 Multiplexing; Demultiplexing
• CPC Class Codes: G02B 6/12004 Combinations of two or more optical elements
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer

Abstract

A miniature monolithic optical add-drop multiplexer that comprises a dispersive optical element, a wavelength filter array and a diverter. The miniature monolithic optical DWDM add-drop multiplexer can be fabricated using micro- and nano-scale techniques common to the semiconductor industry. The operating principles and some characteristics of the DWDM add-drop multiplexer are described. The device will be useful in the field of optical communication as a component within networks that perform all of the necessary switching, adding, dropping, and manipulating of optical signals entirely in the optical domain.

Claims

1. A miniature monolithic optical add-drop multiplexer, comprising:

a monolithic substrate;

a wavelength dispersive optical element fabricated on said monolithic substrate, said wavelength dispersive optical element receiving an input beam having a plurality of spatially overlapping distinct colors and providing an output signal composed of a plurality of spatially separated substantially single-color beams, each substantially single-color beam having a primary wavelength that is different than the primary wavelengths of the other substantially single-color beams;

a wavelength filter array fabricated on said monolithic substrate and having at least one filter element, said at least one filter element receiving a selected one of said plurality of spatially separated substantially single-color optical beams and removing therefrom any portions of beams of other primary wavelengths that were separated incompletely from the selected beam by the wavelength dispersive optical element, thereby providing a purified single-color output beam substantially free of colors associated with other primary wavelengths and having a first direction of propagation; and

a diverter that intercepts said purified single-color output beam and diverts said output beam from the first direction of propagation.

2. The miniature monolithic optical add-drop multiplexer of claim 1, wherein the substrate comprises at least one material selected from the group consisting of silicon, silicon monoxide, silicon dioxide, silicon-germanium alloys, silicon carbide, silicon nitride, and indium phosphide.

3. The miniature monolithic optical add-drop multiplexer of claim 2, wherein the substrate comprises a material that is amenable to processing using semiconductor fabrication processes.

4. The miniature monolithic optical add-drop multiplexer of claim 1, wherein at least one of the wavelength dispersive optical element, the wavelength filter array, and the diverter comprises at least one material selected from the group consisting of silicon, silicon monoxide, silicon dioxide, silicon-germanium alloys, silicon carbide, silicon nitride, and indium phosphide.

5. The miniature monolithic optical add-drop multiplexer of claim 1, wherein at least one of the wavelength dispersive optical element and the wavelength filter array elements comprises an optical waveguide.

6. The miniature monolithic optical add-drop multiplexer of claim 1, wherein at least one of the wavelength dispersive optical element and the wavelength filter array elements comprises a miniature free-space optical element.

7. The miniature monolithic optical add-drop multiplexer of claim 1, further comprising an input optical structure that receives the input beam.

8. The miniature monolithic optical add-drop multiplexer of claim 7, wherein the input optical structure comprises at least one material selected from the group consisting of silicon, silicon monoxide, silicon dioxide, silicon-germanium alloys, silicon carbide, silicon nitride, and indium phosphide.

9. The miniature monolithic optical add-drop multiplexer of claim 7, wherein the input optical structure comprises an optical waveguide.

10. The miniature monolithic optical add-drop multiplexer of claim 7 wherein the input optical structure comprises a miniature free-space optical element.

11. The miniature monolithic optical add-drop multiplexer of claim 7, further comprising an optical waveguide that communicates the input beam from an external source.

12. The miniature monolithic optical add-drop multiplexer of claim 1, further comprising an array of output optical structures having at least one output element, said at least one output element transmitting an output beam.

13. The miniature monolithic optical add-drop multiplexer of claim 12, wherein the array of output optical structures comprise at least one material selected from the group consisting of silicon, silicon monoxide, silicon dioxide, silicon-germanium alloys, silicon carbide, silicon nitride, and indium phosphide.

14. The miniature monolithic optical add-drop multiplexer of claim 12, wherein the array of output optical structures comprise optical waveguides.

15. The miniature monolithic optical add-drop multiplexer of claim 12, wherein the array of output optical structures comprise miniature free-space optical elements.

16. The miniature monolithic optical add-drop multiplexer of claim 12, further comprising an optical waveguide that communicates said output beam from said output element to an external receiver.

17. The miniature monolithic optical add-drop multiplexer of claim 1, wherein each color comprises a narrow band of wavelengths centered on a primary wavelength.

18. The miniature monolithic optical add-drop multiplexer of claim 17, wherein each primary wavelength is designated by the International Telecommunications Union as one of a set of discrete wavelengths to be utilized for optical telecommunications.

19. The miniature monolithic optical add-drop multiplexer of claim 1, wherein the wavelength dispersive optical element is a selected one of a prism, a grating, and a grism.

20. The miniature monolithic optical add-drop multiplexer of claim 1, wherein the wavelength filter array is a selected one of an array of interference filters, an array of waveguide Bragg gratings, an array of Fabry-Perot interferometers, an array of resonantly-coupled waveguide structures, and an array of waveguide ring resonators.

21. The miniature monolithic optical add-drop multiplexer of claim 1, wherein the diverter is fabricated on said miniature monolithic substrate.

22. The miniature monolithic optical add-drop multiplexer of claim 21, wherein the diverter comprises a reflective surface.

23. The miniature monolithic optical add-drop multiplexer of claim 22, wherein the diverter comprises an electromechanical actuator that can move said reflective surface.

24. The miniature monolithic optical add-drop multiplexer of claim 21, wherein the diverter comprises an optical resonator.

25. The miniature monolithic optical add-drop multiplexer of claim 24, wherein the diverter comprises an electrically-driven actuator that can alter a resonant frequency of said optical resonator.

26. The miniature monolithic optical add-drop multiplexer of claim 1, wherein the diverter is capable of being dynamically reconfigured to divert a selected one of the plurality of purified single color output beams.

27. The miniature monolithic optical add-drop multiplexer of claim 1, further comprising:

a second diverter adjacent to said miniature monolithic optical demultiplexer, said diverter receiving a second input beam having a purified single color substantially identical to the purified single color of said output beam that is diverted; and

optionally, a second wavelength dispersive optical element, said second wavelength dispersive optical element capable of combining a plurality of spatially-separated substantially single color optical beams, at least one beam containing primarily a single color that is different than the color of another substantially single color optical beam, into a single beam having a plurality of spatially overlapping distinct colors;

wherein said second diverter is adapted to direct said second input beam for combination with another spatially-separated substantially single color optical beam having a color distinct from that of said second input beam to form a second output beam having a plurality of spatially overlapping distinct colors, using a selected one of said wavelength dispersive optical element and said optionally fabricated second wavelength dispersive optical element to effect said combination.

28. A method of processing an optical beam having a plurality of spatially overlapping colors, comprising the steps of:

providing an assembly of miniature optical elements, comprising;

a monolithic substrate;

a wavelength dispersive optical element fabricated on said monolithic substrate;

a wavelength filter array fabricated on said monolithic substrate; and

a diverter;

receiving an input beam having a plurality of spatially overlapping distinct colors;

dispersing the input beam, by use of the wavelength dispersive optical element, into a plurality of spatially-separated substantially single color optical beams, each beam containing primarily a single color that is different than the color of the other substantially single color optical beams;

filtering said at least one of the substantially single-color optical beams and removing therefrom colors other than the designated primary color of that beam, thereby providing at least one purified single-color output beam having a first direction of propagation, said output beam being substantially free of other colors; and

intercepting said at least one purified single-color output beam and diverting said output beam from the first direction of propagation.

29. The method of claim 28, wherein the input beam is received from an optical waveguide external to said assembly.

30. The method of claim 28, wherein the output beam is transmitted to an optical waveguide external to said assembly.

31. The method of claim 28, further comprising:

providing a second assembly of miniature optical elements, comprising;

a second monolithic substrate;

a second wavelength dispersive optical element fabricated on said monolithic substrate, said second wavelength dispersive optical element capable of combining a plurality of spatially-separated substantially single color optical beams, at least one beam containing primarily a single color that is different than the color of another substantially single color optical beam, into a single beam having a plurality of spatially overlapping distinct colors; and

a second diverter;

receiving a second input beam having a purified single color substantially identical to the purified single color of said output beam that is diverted;

controlling a direction of propagation of said second input beam with said second diverter; and

directing said diverted second input beam and another spatially-separated substantially single color optical beam having a color distinct from that of said diverted second input beam to said second wavelength dispersive optical element to form a second output beam having a plurality of spatially overlapping distinct colors.

32. The method of claim 31, further comprising transmitting said second output beam having a plurality of spatially overlapping distinct colors to an optical waveguide external to said second assembly.

33. The method of claim 31 wherein said monolithic substrate and said second monolithic substrate are the same monolithic substrate.

34. The method of claim 31 wherein said wavelength dispersive optical element and said second wavelength dispersive optical element are the same wavelength dispersive optical element.

35. The method of claim 31 wherein said second input beam is said diverted purified single-color output beam.

36. The method of claim 35 wherein said second input beam is substantially a duplicate of said diverted purified single color output beam.

37. The method of claim 35 wherein said second input beam is a modified version of said diverted purified single color output beam.

38. A method of fabricating a miniature monolithic optical add-drop multiplexer comprising the steps of:

utilizing semiconductor fabrication methods to create a wavelength dispersive optical element and an array of wavelength filtering elements upon a monolithic substrate, the combination of the wavelength dispersive optical element and the array of wavelength filtering elements providing a miniature monolithic optical demultiplexer; and

providing a diverter adjacent to said miniature monolithic optical demultiplexer, said diverter adapted to intercept and divert an optical beam that passes through said miniature monolithic optical demultiplexer.

39. The fabrication method of claim 38, wherein the wavelength dispersive optical element and the wavelength filter array are formed by semiconductor fabrication processes.

40. The fabrication method of claim 39, further comprising the step of fabricating an input optical structure by semiconductor fabrication processes.

41. The fabrication method of claim 39, further comprising the step of fabricating an output optical structure by semiconductor fabrication processes.

42. The fabrication method of claim 39, further comprising the steps of:

providing a second diverter adjacent to said miniature monolithic optical demultiplexer, said diverter receiving a second input beam having a purified single color substantially identical to the purified single color of said output beam that is diverted; and

optionally fabricating, utilizing semiconductor fabrication methods, a second wavelength dispersive optical element, said second wavelength dispersive optical element capable of combining a plurality of spatially-separated substantially single color optical beams, at least one beam containing primarily a single color that is different than the color of another substantially single color optical beam, into a single beam having a plurality of spatially overlapping distinct colors;

wherein said second diverter is adapted to direct said second input beam for combination with another spatially-separated substantially single color optical beam having a color distinct from that of said second input beam to form a second output beam having a plurality of spatially overlapping distinct colors, using a selected one of said wavelength dispersive optical element and said optionally fabricated second wavelength dispersive optical element to effect said combination.

43. The fabrication method of claim 38, wherein the diverter is formed by semiconductor fabrication processes.

44. The fabrication method of claim 43, wherein a diverter component is formed on the monolithic substrate.