Opto electrical test measurement system for integrated photonic devices and circuits
An optical testing circuit on a wafer includes an optical input configured to receive an optical test signal and photodetectors configured to generate corresponding electrical signals in response to optical processing of the optical test signal through the optical testing circuit. The electrical signals are simultaneously sensed by a probe circuit and then processed. In one process, test data from the electrical signals is simultaneously generated at each step of a sweep in wavelength of the optical test signal and output in response to a step change. In another process, the electrical signals are sequentially selected and the sweep in wavelength of the optical test signal is performed for each selected electrical signal to generate the test data.
1. A system for testing an optical testing circuit on a wafer, wherein said optical testing circuit includes: an optical input configured to receive an optical test signal and a plurality of photodetectors configured to generate a corresponding plurality of electrical signals in response to optical processing of said optical test signal through the optical testing circuit, said system comprising:
a light source configured to apply the optical test signal to the optical input with a sweep in wavelength including a plurality of steps;
a probe card configured to simultaneously sense the plurality of electrical signals at each step of the sweep in wavelength;
a conversion circuit configured to generate test data for the simultaneously sensed plurality of electrical signals at each step of the sweep in wavelength and store the test data at each step of the sweep in wavelength;
a power meter configured to sense a change in wavelength of the optical test signal; and
a control circuit configured to respond to the sensed change in wavelength of the optical test signal by reading the stored test data from the conversion circuit.
2. The system of claim 1 , wherein said conversion circuit comprises, for each individual electrical signal of the plurality of electrical signals that is simultaneously sensed, an analog to digital converter circuit that converts the individual electrical signal to a digital signal.
3. The system of claim 2 , wherein said conversion circuit further comprises, for each individual electrical signal of the plurality of electrical signals that is simultaneously sensed, a memory for storing the digital signal.
4. The system of claim 3 , wherein the control circuit reads the stored digital signal from each memory.
5. The system of claim 4 , wherein the power meter generates a trigger signal in response to sensed change in wavelength, said control circuit performing the read of the stored digital signal from each memory in response to said trigger signal.
6. The system of claim 1 , wherein optical processing of said optical test signal through the optical testing circuit comprises passing a signal derived from said optical test signal through at least one optical device under test (DUT) circuit.
7. The system of claim 1 , wherein the power meter generates, in response to the sensed change in wavelength, a trigger signal, said control circuit performing the read of the stored digital signal from each memory in response to said trigger signal.
8. The system of claim 1 , wherein said conversion circuit further comprises, for each individual electrical signal of the plurality of electrical signals that is simultaneously sensed, a controlled gain circuit configured to control gain of each electrical signal of the plurality of electrical signals at each step of the sweep in wavelength.
9. The system of claim 1 , wherein said power meter further provides, for each read of the stored test data, an identification of the step in the sweep in wavelength of the optical test signal that corresponds to the simultaneously sensed plurality of electrical signals from which the stored test data is generated.
10. The system of claim 9 , wherein the identification of the step is an identification of the wavelength for that step.
11. The system of claim 1 , further comprising a multiplexer circuit coupled to receive the plurality of electrical signals and sequentially select an electrical signal from the plurality of electrical signals.
12. The system of claim 11 , wherein the conversion circuit is configured to generate the test data for each sequentially selected electrical signal of the simultaneously sensed plurality of electrical signals.
13. The system of claim 11 , wherein each selected electrical signal of said plurality of electrical signals is converted to a digital signal to generate the test data.
14. The system of claim 13 , further comprising a memory configured to store the digital signal for the test data.