Integrated optical multiplexer and demultiplexer for wavelength division transmission of information

• US 20040184732A1
• Filed: 01/29/2004
• Published: 09/23/2004
• Est. Priority Date: 11/27/2000
• Status: Active Grant

• Current Assignee: Advanced Interfaces Incorporated
• Original Assignee: Advanced Interfaces Incorporated
• Inventors: Zhou, Zhiping ("James")
• Granted Patent: US 7,050,675 B2
• Time in Patent Office: Days
• US Class Current: 385/37
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0259 Monolithic
• CPC Class Codes: G01J 3/18 using diffraction elements, e.g. grating gratings per se G02B
• CPC Class Codes: G02B 2006/12107 Grating
• CPC Class Codes: G02B 2006/12173 Masking
• CPC Class Codes: G02B 2006/12176 Etching
• CPC Class Codes: G02B 5/1809 with pitch less than or comparable to the wavelength
• CPC Class Codes: G02B 6/12002 Three-dimensional structures
• 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
• CPC Class Codes: G02B 6/124 Geodesic lenses or integrated gratings
• CPC Class Codes: G02B 6/43 Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections
• CPC Class Codes: H01L 27/1443 with at least one potential jump or surface barrier
• CPC Class Codes: H01L 31/105 the potential barrier being of the PIN type
• CPC Class Codes: H01L 31/12 structurally associated with, e.g. formed in or on a common substrate with, one or more electric light sources, e.g. electroluminescent light sources, and electrically or optically coupled thereto semiconductor devices with at least one potential barrier or surface barrier adapted for light emission H01L33/00; amplifiers using electroluminescent element and photocell H03F17/00; electroluminescent light sources per se H05B33/00
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table
• CPC Class Codes: H01S 5/0268 Integrated waveguide grating router, e.g. emission of a multi-wavelength laser array is combined by a "dragon router"
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

An integrated optical multiplexer and/or demultiplexer is provided for on-chip optical interconnection between electronic components on an integrated circuit chip and between chips, and for high density telecommunications. The multiplexer and/or demultiplexer includes an integrated circuit substrate formed with an array of photo detectors (for the demultiplexer) or photo emitters (for the multiplexer). Conditioning electronics is formed on the substrate and is coupled to the photo elements for conditioning electronic data for optical transmission in the case of the multiplexer or for conditioning optical signals into electronic data in the case of the demultiplexer. A first layer of optically transparent material is formed on the substrate overlying the detectors and/or emitters and a second layer of optically transparent material is formed on the first layer and functions as an optical waveguide. A binary blazed grating is formed at the interface of the first and second layers of optically transparent material. In use, discrete wavelength optical signals are modulated with data and emitted by the photo emitters. The discrete wavelengths are intercepted by the binary blazed grating overlying the emitters and multiplexed into a polychromatic beam for transmission through the waveguide. At the demultiplexer, the discrete wavelengths are separated by the binary blazed grating and directed to corresponding ones of the photo detectors. The conditioning electronics coupled to the photo detectors receives the output of the photo detectors, demodulates the output to extract the data, and formats the data for communication with electronic components on the integrated circuit.

Claims

1. A method for manufacturing an optical demultiplexer on an integrated circuit substrate for wavelength division transmission of information, comprising:

fabricating an array of optical detectors on the substrate based on a predetermined optical detector design analysis;

fabricating a signal conditioning circuit on the substrate adjacent to the array of optical detectors and coupling the signal conditioning circuit to the array of optical detectors;

forming a first layer of optically transparent material on the substrate covering the array of optical detectors and signal conditioning circuit;

fabricating a binary blazed grating on the first layer of optically transparent material; and

forming a second layer of optically transparent material over the first layer and binary blazed grating to form an optical waveguide for diffracting incident light.

2. The method for manufacturing an optical demultiplexer of claim 1 wherein a thickness of the first layer of optically transparent material is determined based on a specific application for the optical demultiplexer.

3. The method for manufacturing an optical demultiplexer of claim 1 wherein the array of optical detectors is formed on a silicon P-I-N structure.

4. The method for manufacturing an optical demultiplexer of claim 3 wherein the array of optical detectors is formed by removing a silicon dioxide layer from the “

N”

regions of the substrate, forming a trench in the “

N”

regions and filling the trench with “

N”

type doped polysilicon.

5. The method for manufacturing an optical demultiplexer of claim 4 wherein the step of forming a trench in the “

N”

regions is performed via inductive coupled plasma etching.

6. The method for manufacturing an optical demultiplexer of claim 4 wherein the step of filling the trench with “

N”

type doped polysilicon is performed via a low-pressure chemical vapor deposition process.

7. The method for manufacturing an optical demultiplexer of claim 6 further comprising the step of removing “

N”

type doped polysilicon from the silicon dioxide layer.

8. The method for manufacturing an optical demultiplexer of claim 3 wherein the array of optical detectors is formed by removing a silicon dioxide layer from the “

P”

regions of the substrate, forming a trench in the “

P”

regions and filling the trench with “

P”

type doped polsilicon.

9. The method for manufacturing an optical demultiplexer of claim 8 wherein the step of forming a trench in the “

P”

regions is performed via inductive coupled plasma etching.

10. The method for manufacturing an optical demultiplexer of claim 8 wherein the step of filling the trench with “

P”

type doped polysilicon is performed via a low-pressure chemical vapor deposition process.

11. The method for manufacturing an optical demultiplexer of claim 10 further comprising the step of removing “

P”

type doped polysilicon from the silicon dioxide layer.

12. The method for manufacturing an optical demultiplexer of claim 1 wherein a length for each optical detector is determined based on a predetermined output optical pattern from the binary blazed grating.

13. The method for manufacturing an optical demultiplexer of claim 1 wherein the step of forming a first layer of optically transparent material comprises depositing a material having a low index of refraction on the substrate and the array of optical detectors formed on the substrate.

14. The method for manufacturing an optical demultiplexer of claim 13 wherein the deposited material is selected from a group consisting of a polymer or silica.

15. The method for manufacturing an optical demultiplexer of claim 13 wherein the deposited material has an index of refraction from about 1.0 to about 2.0.

16. The method for manufacturing an optical demultiplexer of claim 1 wherein the step of forming a second layer of optically transparent material comprises depositing a material having an index of refraction that is greater than the index of refraction of the first layer of optically transparent material.

17. The method for manufacturing an optical demultiplexer of claim 1 wherein the step of forming a second layer of optically transparent material comprises depositing a material having an index of refraction that is different from the index of refraction of the first layer of optically transparent material.

18. The method for manufacturing an optical demultiplexer of claim 16 wherein the deposited material is selected from a group consisting of silicon nitride, a polymer, silica, silicon, polysilicon or LiNbO3.

19. The method for manufacturing an optical demultiplexer of claim 1 wherein the incident light comprises a plurality of beams each having a different and discrete wavelength.

20. The method for manufacturing an optical demultiplexer of claim 1 wherein the incident light originates from a device on the integrated circuit substrate.

21. The method for manufacturing an optical demultiplexer of claim 1 wherein the incident light originates from outside the integrated circuit substrate.

22. The method for manufacturing an optical demultiplexer of claim 1 wherein the binary blazed grating diffracts the incident light into a plurality of component beams of discrete wavelengths that are intercepted by a corresponding optical detector in the array of optical detectors.

23. The method for manufacturing an optical demultiplexer of claim 1 wherein the binary blazed grating comprises a plurality of ridges and a plurality of troughs, the width and the spacing of the ridges and troughs being varied during fabrication to provide a plurality of localized subwavelength, submicrometer grating features within a grating period.

24. The method for manufacturing an optical demultiplexer of claim 1 wherein the step of fabricating a binary glazed grating on the first layer comprises the steps of designing a hard mask for the binary blazed grating through a simulation.

25. The method for manufacturing an optical demultiplexer of claim 24 wherein the step of fabricating a binary blazed grating further comprises patterning the hard mask on the first layer of optically transparent material and etching the binary blazed grating.

26. The method for manufacturing an optical demultiplexer of claim 1 wherein the step of forming a second layer of optically transparent material is performed via a low-pressure chemical vapor deposition.

27. The method for manufacturing an optical demultiplexer of claim 1 further comprising the step of planarizing the second layer of optically transparent material.

28. The method for manufacturing an optical demultiplexer of claim 1 further comprising forming the optical waveguide using a conventional planar light circuit process to manipulate the path of the incident light.

29. The method for manufacturing an optical demultiplexer of claim 1 further comprising exposing a plurality of contact pads of the signal conditioning circuit via lithography and etching.

30. The method for manufacturing an optical demultiplexer of claim 1 further comprising placing interdigitated electrodes on each optical detector during fabrication of the signal conditioning circuit.

35. The method for manufacturing an optical multiplexer of claim 19 wherein the step of forming a second layer of optically transparent material comprises depositing a material having an index of refraction that is greater than the index of refraction of the first layer of optically transparent material.

31. A method for manufacturing an optical multiplexer on an integrated circuit substrate for combining light beams of discrete wavelengths into a single polychromatic beam for wavelength division transmission of information, comprising:

positioning an array of optical emitters on the substrate;

fabricating a signal conditioning circuit on the substrate adjacent to the array of optical emitters and coupling the signal conditioning circuit to the array of optical emitters;

forming a first layer of optically transparent material on the substrate covering the array of optical emitters and signal conditioning circuit;

fabricating a binary blazed grating on the first layer of optically transparent material; and

forming a second layer of optically transparent material over the first layer and binary blazed grating to form an optical waveguide for intercepting light beams of discrete wavelengths and combining the intercepted light beams into a polychromatic light beam for transmission through the optical waveguide.

32. The method for manufacturing an optical multiplexer of claim 31 wherein the step of forming a first layer of optically transparent material comprises depositing a material having a low index of refraction on the substrate and the array of optical emitters formed on the substrate.

33. The method for manufacturing an optical multiplexer of claim 31 wherein the deposited material is selected from a group consisting of a polymer or silica.

37. The method for manufacturing an optical multiplexer of claim 31 wherein the step of forming a second layer of optically transparent material comprises depositing a material having an index of refraction that is different from the index of refraction of the first layer.

38. The method for manufacturing an optical multiplexer of claim 31 wherein the deposited material is selected from a group consisting of silicon nitride, a polymer, silica, silicon, polysilicon or LiNbO3.

39. The method for manufacturing an optical multiplexer of claim 31 further comprising fabricating the binary blazed grating on the first layer of optically transparent material.

40. The method for manufacturing an optical multiplexer of claim 31 further comprising fabricating the binary blazed grating on the second layer of optically transparent material.