Wafer level testing of optical components
A system may include a wafer that includes ICs and defines cavities. Each cavity may be formed in a BEOL layer of the wafer and proximate a different IC. The system may also include an interposer that includes a transparent layer configured to permit optical signals to pass through. The interposer may also include at least one waveguide located proximate the transparent layer. The at least one waveguide may be configured to adiabatically couple at least one optical signal out of the multiple ICs. Further, the interposer may include a redirecting element optically coupled to the at least one the waveguide. The redirecting element may be located proximate the transparent layer and may be configured to receive the at least one optical signal from the at least one waveguide. The redirecting element may also be configured to vertically redirect the at least one optical signal towards the transparent layer.
1. A system comprising:
a wafer comprising a plurality of integrated circuits (ICs) and the wafer defining a plurality of cavities; and
an interposer configured to test the plurality of ICs and the interposer being configured to be placed in one cavity of the plurality of cavities at a time proximate a corresponding IC of the plurality of ICs, the interposer comprising:
a transparent layer; and
at least one waveguide, the at least one waveguide configured to couple at least one optical signal out the plurality of ICs
wherein:
the at least one optical signal comprises a first optical signal and the at least one waveguide comprises a first waveguide and a second waveguide, the first waveguide is configured to adiabatically couple the first optical signal out of a corresponding IC of the plurality of ICs; and
the system further comprises a testing fixture located proximate the transparent layer, the testing fixture configured to provide a second optical signal, the second waveguide configured to receive the second optical signal and to adiabatically couple the second optical signal into the corresponding IC of the plurality of ICs.
2. The system of claim 1 , the system further comprising an optical component located proximate the transparent layer and a redirecting element, the optical component configured to receive at least one redirected optical signal from the redirecting element.
3. The system of claim 2 , wherein the optical component is configured to provide an electrical signal to an external device, the electrical signal representative of the at least one redirected optical signal.
4. The system of claim 2 , wherein the optical component comprises at least one of a photo-detector, a photodiode, and an optical fiber.
5. The system of claim 1 , wherein each IC of the plurality of ICs comprises one or more adiabatic couplers and the at least one waveguide is configured to adiabatically couple the at least one optical signal out of at least one adiabatic coupler of the one or more adiabatic couplers in a corresponding IC of the plurality of ICs.
6. The system of claim 2 , wherein:
the redirecting element comprises a grating coupler configured to redirect the at least one optical signal; and
the interposer further comprises a mirror located below the grating coupler, wherein the mirror is configured to reduce degradation of the at least one redirected optical signal.
7. The system of claim 2 , wherein the redirecting element comprises a mirror configured to vertically redirect the at least one optical signal towards the transparent layer.
8. The system of claim 1 , the system further comprising a removable material configured to assist in optically coupling the at least one waveguide with the plurality of ICs.
9. The system of claim 1 , wherein each IC of the plurality of ICs comprise at least one of a photonic integrated circuit and an optical integrated circuit.
10. The system of claim 1 , wherein the interposer further comprises a redirecting element optically coupled to the at least one waveguide, the redirecting element configured to receive the at least one optical signal from the at least one waveguide and to redirect the at least one optical signal towards the transparent layer.
11. A system comprising:
a wafer comprising a plurality of integrated circuits (ICs) and the wafer defining a plurality of cavities; and
an interposer configured to test the plurality of ICs and the interposer being configured to be placed in one cavity of the plurality of cavities at a time proximate a corresponding IC of the plurality of ICs, the interposer comprising:
a transparent layer; and
at least one waveguide, the at least one waveguide configured to couple at least one optical signal out the plurality of ICs; wherein
each IC of the plurality of ICs comprises one or more adiabatic couplers; and
the at least one waveguide is configured to adiabatically couple the at least one optical signal out of at least one adiabatic coupler of the one or more adiabatic couplers in a corresponding IC of the plurality of ICs
wherein:
the plurality of cavities are formed in the wafer such that a portion of a front end of line (FEOL) layer of the wafer is located above the one or more adiabatic couplers in each IC of the plurality of ICs and the portion of the FEOL layer is thin enough to enable optical coupling between the one or more adiabatic couplers in each IC of the plurality of ICs and the at least one waveguide in the interposer.
12. The system of claim 11 , wherein:
the at least one optical signal comprises a first optical signal and the at least one waveguide comprises a first waveguide and a second waveguide, the first waveguide is configured to adiabatically couple the first optical signal out of a corresponding IC of the plurality of ICs; and
the system further comprises a testing fixture located proximate the transparent layer, the testing fixture configured to provide a second optical signal, the second waveguide configured to receive the second optical signal and to adiabatically couple the second optical signal into the corresponding IC of the plurality of ICs.
13. A system comprising:
a wafer comprising a plurality of integrated circuits (ICs) and the wafer defining a plurality of cavities; and
an interposer configured to test the plurality of ICs and the interposer being configured to be placed in one cavity of the plurality of cavities at a time proximate a corresponding IC of the plurality of ICs, the interposer comprising:
a transparent layer; and
at least one waveguide, the at least one waveguide configured to couple at least one optical signal out the plurality of ICs,
wherein, the at least one optical signal comprises a first optical signal and the at least one waveguide comprises:
a first waveguide configured to adiabatically couple the first optical signal out of a corresponding IC of the plurality of ICs; and
a second waveguide optically coupled to the first waveguide and a redirecting element, the second waveguide located proximate the first waveguide with a portion of the transparent layer positioned between the first waveguide and the second waveguide, the second waveguide being configured to adiabatically couple the first optical signal out of the first waveguide and to provide the first optical signal to the redirecting element.
14. The system of claim 13 , the interposer further comprising:
a substrate configured to permit optical signals to pass through; and
an anti-reflection (AR) coating located on a top surface of the transparent layer between the substrate and the transparent layer.
15. The system of claim 14 , wherein the redirecting element comprises a grating coupler optically coupled to the second waveguide and located within the transparent layer, the grating coupler configured to receive the at least one optical signal from the second waveguide and to vertically redirect the at least one optical signal towards the thick substrate.