Semiconductor device and wafer with reference circuit and related methods
A semiconductor device may include a semiconductor wafer, and a reference circuit carried by the semiconductor wafer. The reference circuit may include optical DUTs, a first set of photodetectors coupled to outputs of the optical DUTs, an optical splitter coupled to inputs of the optical DUTs, and a second set of photodetectors coupled to the optical splitter. The optical splitter is to be coupled to an optical source and configured to transmit a reference optical signal to the first set of photodetectors via the optical DUTs and the second set of photodetectors.
1. A circuit configured to determine an optical loss, the circuit comprising:
a plurality of optical devices under tests (DUTs) configured to receive a plurality of reference optical signals;
a first plurality of photodetectors coupled to outputs of the plurality of optical DUTs; and
a second plurality of photodetectors having inputs configured to receive the plurality of reference optical signals.
2. The circuit of claim 1 , further comprising at least one optical splitter comprising an input coupled to at least one optical source, and a plurality of outputs coupled to inputs of the plurality of optical DUTs, the at least one optical splitter being configured to provide the plurality of reference optical signals to the plurality of optical DUTS and to transmit the plurality of reference optical signals to the first plurality of photodetectors via the plurality of optical DUTs.
3. The circuit of claim 2 , the at least one optical splitter being further configured to provide the plurality of reference optical signals to the second plurality of photodetectors.
4. The circuit of claim 2 , wherein the at least one optical splitter comprises a single optical splitter.
5. The circuit of claim 2 , wherein the at least one optical splitter comprises a first optical splitter and a second optical splitter, the first optical splitter having first outputs coupled to inputs of the plurality of optical DUTs, the second optical splitter having second outputs coupled to inputs of the second plurality of photodetectors.
6. The circuit of claim 5 , the first optical splitter comprising a first input coupled to a first output of the at least one optical source, the second optical splitter comprising a second input coupled to a second output of the at least one optical source.
7. The circuit of claim 1 , wherein the first plurality of photodetectors comprises photodiodes.
8. The circuit of claim 1 , wherein the first plurality of photodetectors and the second plurality of photodetectors have matched optical responsivities.
9. A circuit configured to determine an optical loss, the circuit comprising:
at least one optical splitter configured to generate a plurality of reference optical signals;
a plurality of optical devices under tests (DUTs) arranged as N parallel channels of optical DUTs, the N parallel channels of optical DUTs being configured to receive the plurality of reference optical signals from the at least one optical splitter;
a first plurality of photodetectors, a respective one of the first plurality of photodetectors being coupled to an output of a respective one of the N parallel channels of optical DUTs; and
a second plurality of photodetectors having inputs configured to receive the plurality of reference optical signals from the at least one optical splitter.
10. The circuit of claim 9 , wherein a respective one of the N parallel channels of optical DUTs is configured to receive a respective one of the plurality of reference optical signals.
11. The circuit of claim 9 , wherein the plurality of reference optical signals comprises balanced optical signals.
12. The circuit of claim 9 , wherein the first plurality of photodetectors are spaced apart from the second plurality of photodetectors.
13. The circuit of claim 9 , further comprising a grating coupler coupled to an input of the at least one optical splitter.
14. The circuit of claim 9 , further comprising a first plurality of output terminals, a respective one of the first plurality of output terminals being coupled to a respective one of the first plurality of photodetectors.
15. The circuit of claim 9 , further comprising a summer circuit configured to receive and sum outputs of the second plurality of photodetectors.
16. The circuit of claim 15 , further comprising a second output terminal coupled to an output of the summer circuit.
17. A method, comprising:
generating, using at least one optical splitter, a plurality of reference optical signals;
providing the plurality of reference optical signals to a plurality of optical devices under tests (DUTs) arranged as N parallel channels of optical DUTs;
generating a first plurality of optical output signals at outputs of the N parallel channels of optical DUTs based on the plurality of reference optical signals;
generating, using a first plurality of photodetectors, a first electrical output signal based on the first plurality of optical output signals;
generating, using a second plurality of photodetectors, a second electrical output signal based on the plurality of reference optical signals; and
determining an optical loss of the plurality of optical DUTs based on a comparison between the first electrical output signal and the second electrical output signal.
18. The method of claim 17 , wherein the plurality of reference optical signals comprises balanced reference optical signals.
19. The method of claim 17 , wherein the first plurality of photodetectors and the second plurality of photodetectors have matched optical responsivities.
20. The method of claim 17 , wherein generating the plurality of reference optical signals comprises:
receiving, by an optical grating, an optical input from an optical source; and
providing an output of the optical grating to an input of the at least one optical splitter to generate the plurality of reference optical signals.