Opto electrical test measurement system for integrated photonic devices and circuits

Patent metadata

Field	Value
Publication number	US-2017307687-A1
Application number	US-201715489127-A
Country	US
Kind code	A1
Filing date	Apr 17, 2017
Priority date	Apr 20, 2016
Publication date	Oct 26, 2017
Grant date	—

Abstract

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.

First claim

1 . A method 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 method comprising:
applying the optical test signal with a sweep in wavelength; simultaneously sensing the plurality of electrical signals at each step of the sweep in wavelength; generating test data for the simultaneously sensed plurality of electrical signals at each step of the sweep in wavelength; storing the test data at each step of the sweep in wavelength; sensing a change in wavelength of the optical test signal; and in response to the sensed change in wavelength of the optical test signal, outputting the stored test data.

2 . The method of claim 1 , wherein generating test data comprises, for each individual electrical signal of the plurality of electrical signals that is simultaneously sensed, converting the individual electrical signal to a digital signal.

3 . The method of claim 2 , wherein storing the test data comprises, for each individual electrical signal of the plurality of electrical signals that is simultaneously sensed, storing the digital signal in a memory.

4 . The method of claim 3 , wherein outputting comprises reading the stored digital signal from each memory.

5 . The method of claim 4 , wherein sensing the change in wavelength comprises generating a trigger signal in response to the sensed change in wavelength, and wherein reading is performed in response to said trigger signal.

6 . The method 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 method of claim 1 , wherein sensing the change in wavelength comprises generating a trigger signal in response to the sensed change in wavelength, and wherein outputting is performed in response to said trigger signal.

8 . The method of claim 1 , further comprising controlling a gain of each electrical signal of the plurality of electrical signals at each step of the sweep in wavelength.

9 . The method of claim 1 , wherein outputting further comprises providing, with each output of 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 method of claim 9 , wherein the identification of the step is an identification of the wavelength for that step.

11 . 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 with a sweep in wavelength; 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.

12 . The system of claim 11 , 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.

13 . The system of claim 12 , 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.

14 . The system of claim 13 , wherein the control circuit reads the stored digital signal from each memory.

15 . The system of claim 14 , wherein the power meter operates, in response to the sensed change in wavelength, by generating a trigger signal, said control circuit performing the read of the stored digital signal from each memory in response to said trigger signal.

16 . The system of claim 11 , 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.

17 . The system of claim 11 , wherein the power meter operates, in response to the sensed change in wavelength, by generating a trigger signal, said control circuit performing the read of the stored digital signal from each memory in response to said trigger signal.

18 . The system of claim 11 , 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.

19 . The system of claim 11 , 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.

20 . The system of claim 19 , wherein the identification of the step is an identification of the wavelength for that step.

21 . A method 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 method comprising:
sequentially selecting an electrical signal from the plurality of electrical signals; and for each selected electrical signal, performing a process as follows: sweeping the wavelength of the optical test signal; sensing the selected electrical signal; generating test data from the selected electrical signal over the sweep in wavelength of the optical test signal; determining whether all electrical signals of the plurality of electrical signals have been selected; and if not, then changing the selected electrical signal and repeating the process.

22 . 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

Assignees

• St Microelectronics Crolles 2 Sas

Inventors

• Grosse Philippe
• Le Maitre Patrick
• Carpentier Jean-Francois

Classifications

• G01R35/00

  Testing or calibrating of apparatus covered by the other groups of this subclass · CPC title

• G02B6/12004

  Combinations of two or more optical elements · CPC title

• G01R31/27

  Testing of devices without physical removal from the circuit of which they form part, e.g. compensating for effects surrounding elements {(testing printed circuit boards G01R31/2801)} · CPC title

• G02B6/34

  utilising prism or grating {(G02B6/293 takes precedence)} · CPC title

• G01R31/303

  of integrated circuits (G01R31/305 - G01R31/315 take precedence) · CPC title