Three-dimensional optical path with 1×m output ports using SOI-based vertically-splitting waveguides

• US 10,222,564 B2
• Filed: 04/26/2018
• Issued: 03/05/2019
• Est. Priority Date: 05/19/2017
• Status: Active Grant

• Current Assignee: Adolite Inc.
• Original Assignee: Adolite Inc.
• Inventors: Jou, Abraham, Wu, Paul Mao-Jen
• Primary Examiner(s): Jordan, Andrew
• Application Number:
  US15/963,665
• Publication Number:
  US 20180335588A1
• Time in Patent Office: 313 Days
• CPC Class Codes: G02B 6/12011 characterised by the arrayed waveguides, e.g. comprising a filled groove in the array section
• CPC Class Codes: G02B 6/1221 made from organic materials
• CPC Class Codes: G02B 6/3652 the additional structures being prepositioning mounting areas, allowing only movement in one dimension, e.g. grooves, trenches or vias in the microbench surface, i.e. self aligning supporting carriers
• CPC Class Codes: G02B 6/4206 Optical features G02B6/4207, G02B6/421 take precedence
• CPC Class Codes: G02B 6/421 the intermediate optical component consisting of a short length of fibre, e.g. fibre stub
• CPC Class Codes: G02B 6/4212 the intermediate optical element being a coupling medium interposed therebetween, e.g. epoxy resin, refractive index matching material, index grease, matching liquid or gel
• 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 6/425 Optical features semiconductor laser arrays H01S5/40; hybrid LED arrays H01L25/0753; monolithic LED arrays H01L27/153
• CPC Class Codes: G02B 6/4259 of the transparent type
• CPC Class Codes: G02B 6/4279 Radio frequency signal propagation aspects of the electrical connection, high frequency adaptations
• CPC Class Codes: G02B 6/428 containing printed circuit boards [PCB]
• CPC Class Codes: H01S 5/02251 using optical fibres
• CPC Class Codes: H01S 5/02255 using beam deflecting elements
• CPC Class Codes: H01S 5/183 having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
• CPC Class Codes: H04B 10/25 Arrangements specific to fibre transmission
• CPC Class Codes: H04B 10/506 Multiwavelength transmitters
• CPC Class Codes: H04B 10/67 Optical arrangements in the receiver
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H05K 1/0274 Optical details, e.g. printed circuits comprising integral optical means H05K1/0269 takes precedence; coupling light guides with opto-electronic components G02B6/42
• CPC Class Codes: H05K 1/189 characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence
• CPC Class Codes: H05K 2201/10121 : Optical component, e.g. opto-electronic component
• CPC Class Codes: H05K 2201/10151 : Sensor

Abstract

A three dimensional optical interconnect device having one input and multiple output ports mounted on the same surface of a SOI wafer is disclosed. The first Si surface has a silicon waveguide with a straight portion, a first and a second 45 degree end reflectors and multiple optical splitters arranged in a sequence along the straight portion. The second silicon surface has an insulating layer and an active optical input device (VCSEL laser) and multiple receiver ports mounted on the insulating layer. The first end reflector is aligned to the input optical device, the optical splitters and the second end reflector are sequentially aligned to the photodetectors respectively. Multiple optical paths are formed from the input optical device to each of photodetectors by a reflection from each aligned optical splitter and a reflection from the second end reflector through the silicon substrate.

Claims

1. An optical interconnect apparatus, comprising:

a silicon substrate having a first silicon surface and a second silicon surface substantially parallel to each other, wherein an oxide layer is embedded under the first silicon surface, and wherein an insulating layer is disposed on the second silicon surface;

a silicon waveguide device with a straight portion and two ends fabricated on the first silicon surface, wherein the silicon waveguide device comprises a first and a second 45 degree end reflectors at two ends and a plurality of optical splitters arranged in a sequence along the straight portion; and

an optical engine mounted on the insulating layer of the second silicon surface, wherein the optical engine comprises;

a plurality of conductive lines patterned on the insulating layer;

an input optical device, and a plurality of output optical devices, wherein the first end reflector is aligned to the input optical device, wherein the second end reflector and each of the plurality of optical splitters are sequentially aligned to one of the plurality of output optical devices respectively;

wherein multiple optical paths are formed from the input optical device to each of the plurality of output optical devices by a reflection from each aligned optical splitter and a reflection from the second end reflector through the silicon substrate.

2. The optical interconnect apparatus of claim 1, wherein the plurality of the optical splitters comprises 45 degree micro-reflectors, wherein the 45 degree micro-reflectors and the second end reflector have sequentially larger reflective areas.

3. The optical interconnect apparatus of claim 2, wherein the plurality of optical splitters each comprises a recess structure, wherein the recess structure is arranged to have sequentially deeper recess along the silicon waveguide.

4. The optical interconnect apparatus of claim 1, wherein the silicon waveguide device is fabricated in (100) silicon crystal facet of the first silicon surface, and the micro-reflectors are formed on (110) crystal facet.

5. The optical interconnect apparatus of claim 1, wherein a layer of oxide is grown on the silicon waveguide device to form a cladding structure.

6. The optical interconnect apparatus of claim 1, wherein the input optical device is a vertical cavity surface emission laser (VCSEL), or a vertical cavity surface emission laser array (VCSELs) emitting infrared light.

7. The optical interconnect apparatus of claim 6, wherein the vertical cavity surface emission laser array (VCSELs) is a 1×

4 array and the silicon waveguide device has 4 channels.

8. The optical interconnect apparatus of claim 1, wherein the plurality of output optical devices is photodiodes (PDs) or photodiode arrays (PDs), wherein the photodiodes or photodiode arrays are a hybrid type of silicon and germanium.

9. The optical interconnect apparatus of claim 1, wherein the optical engine further comprises IC drivers, amplifiers and RF circuitry.

10. The optical interconnect apparatus of claim 1, wherein the silicon substrate has a thickness ranging from 50 microns to 2 mm.

11. The optical interconnect apparatus of claim 1, wherein the silicon substrate is a SOI wafer.

12. The optical interconnect apparatus of claim 1, wherein the approximately parallel first and second silicon surfaces of the silicon substrate are wedged with an angle smaller than 10 degrees.

13. The optical interconnect apparatus of claim 1, wherein the optical engine and the plurality of conductive lines are interconnected by solder bumps coated with Au/Ni and wherein an adhesive layer on top of the plurality of conductive lines attach the optical engine to the silicon substrate.

14. The optical interconnect apparatus of claim 1, wherein the first silicon surface has a silicon layer of 4 microns to 100 microns thick and wherein the oxide layer is thicker than 5 microns.

15. The optical interconnect apparatus of claim 1, wherein the plurality of conductive lines comprises tungsten (W), aluminum (Al), copper (Cu), gold (Au), silver (Ag), stainless steel, or an alloy.

16. The optical interconnect apparatus of claim 1, wherein the plurality of conductive lines are high speed RF transmission lines capable of operating at 25 Gbps per channel.

17. A method of fabricating an optical interconnect apparatus, comprising:

providing a silicon substrate having a first silicon surface with an embedded oxide layer and a second silicon surface for optoelectronics;

patterning strip-like waveguides on the first silicon surface and exposing the oxide surface under the silicon layer;

patterning 45 degree end reflectors at ends of silicon waveguides;

patterning multiple 45 degree reflectors having sequentially larger reflective areas;

turning the silicon substrate over to work on the second silicon surface;

depositing an insulating layer on the second silicon surface;

patterning conductive lines on the insulating layer of the second silicon surface; and

growing bonding pillars or solder bumps on the conductive lines to connect to an input optical device and a plurality of output optical devices, wherein the input optical device and the plurality of output optical devices are aligned with the multiple 45 degree reflectors and end reflectors.

18. A method of fabricating an optical interconnect apparatus in claim 17, further comprising depositing an adhesive layer on the second silicon surface, wherein the adhesive layer comprises an anisotropic conductive film (ACF).

19. The method of fabricating an optical interconnect apparatus in claim 17, wherein patterning the conductive lines comprises forming trenches and filling in metal in the trenches, followed by removing excess metal by polishing (CMP) or by selective etch to clean up metal outside the trenches.

20. The method of fabricating an optical interconnect apparatus in claim 17, wherein patterning the conductive lines comprises depositing a metal layer, patterning the metal layer into lines, followed by removing excess metal by polishing (CMP) or by selective etch.