Monolithic opto-isolators
Monolithic opto-isolators and arrays of monolithic opto-isolators are disclosed. The monolithic opto-isolators are manufactured in a single semiconductor wafer where they may be tested at the wafer level before each opto-isolator is singulated from the wafer. The monolithic opto-isolators include a VCSEL monolithically produced adjacent to a photodiode where an axis of optical signal transmission of the VCSEL is substantially parallel to an axis of optical signal reception by the photodiode.
1. An opto-isolator, comprising:
a vertical cavity surface emitting laser (VCSEL) diode comprising a first PN junction with a first p layer and a first n layer;
a photodiode disposed adjacent to the VCSEL such that an axis of transmission of the VCSEL is parallel to an axis of reception of the photodiode; and
at least one reflective surface configured to optically couple substantially all of the light produced by the VCSEL with the photodiode.
2. An opto-isolator according to claim 1 , wherein the VCSEL and the photodiode are monolithically produced on the same semiconductor wafer.
3. An opto-isolator according to claim 1 , wherein the VCSEL and the photodiode are supported by a common substrate.
4. An opto-isolator according to claim 1 , wherein the at least one reflective surfaces includes a first reflective surface and a second reflective surface, the first reflective surface disposed along the axis of transmission of the VCSEL at an angle of about 45 degrees to the axis of transmission of the VCSEL, the second reflective surface disposed along the axis of reception of the photodiode and at an angle of about 45 degrees to the axis of reception of the photodiode.
5. An opto-isolator according to claim 1 , wherein the at least one reflective surface is etched into a surface of the opto-isolator.
6. An opto-isolator according to claim 5 , wherein the surface of the opto-isolator into which the at least one reflective surface is etched includes a semi-conductor material.
7. An opto-isolator according to claim 6 , wherein the semi-conductor material includes GaAs.
8. An opto-isolator according to claim 1 , further comprising a trench located between the VCSEL diode and the photodiode, the trench being configured to increase electrical isolation between the VCSEL diode and the photodiode.
9. An opto-isolator according to claim 8 , wherein the trench is filled with a polymer.
10. An opto-isolator according to claim 9 , wherein the polymer has a substantially similar index of refraction to GaAs.
11. An opto-isolator according to claim 9 , wherein the polymer forms the at least one reflective surface.
12. An opto-isolator according to claim 1 , further comprising two VCSEL bond pads configured to provide electrical current to the VCSEL diode; and two photodiode bond pads configured to provide electrical current to the photodiode.
13. An opto-isolator according to claim 1 , wherein one of the at least one reflective surfaces is configured to direct light at least partially through air to a second of the at least one reflective surface.
14. An opto-isolator according to claim 1 , further comprising a first post, wherein the first post includes a first reflective surface of the at least one reflective surfaces located at a first end of the first post.
15. An opto-isolator according to claim 14 , further comprising a second post, wherein the second post includes a second reflective surface of the at least one reflective surfaces at a first end of the second post, wherein a second end of the first post is disposed over the VCSEL and a second end of the second post is disposed over the photodiode.
16. An opto-isolator according to claim 15 , wherein the first post is disposed along the axis of transmission of the VCSEL and the second post is disposed along the axis of reception of the photodiode.
17. An opto-isolator according to claim 14 , further comprising a first polymeric coating at least partially encasing the VCSEL and the first post.
18. An opto-isolator according to claim 17 , further comprising a second polymeric coating at least partially encasing the photodiode and a second post.
19. An opto-isolator according to claim 1 , wherein the at least one reflective surface includes a lens for focusing light.
20. An array of opto-isolators comprising a plurality of opto-isolators according to claim 1 .
21. An array of opto-isolators according to claim 20 , wherein the plurality of opto-isolators are manufactured in a common wafer.
22. An electronic device comprising an opto-isolator according to claim 1 .