Photodiode Testing via Segmented Optical Terminals
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Solution Overview
Problem
Implementing a grating coupler for wafer-level testing of receiver photodiodes in photonic integrated circuits (PICs) without impacting the PIC's operation or causing damage during the V-groove process is challenging.
Innovation Solution
A designed-for-test (DFT) structure for PICs, which includes a photodiode with a test optical terminal and an operational optical terminal in different locations, optically communicated with a grating coupler and an optical component respectively, using dedicated optical signal paths to enable testing without interfering with the operational path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a grating coupler is implemented for wafer-level testing of receiver photodiodes, then testing capability is improved, but the PIC operation may be impacted or damage may occur during the V-groove process
Solution Approach 1:
The photodiode is provided with two separate optical terminals: a first optical terminal for operational use and a second optical terminal for testing. This segmentation allows the testing function to be performed through the second terminal via the grating coupler without impacting the operational terminal, thereby resolving the contradiction between testing capability and PIC operation reliability
Solution Approach 2:
The second optical terminal serves as an intermediary element that enables testing through the grating coupler without directly involving the operational optical terminal. This intermediary structure allows testing signals to be coupled into the photodiode through a separate path, preventing damage to the operational path while maintaining full operational capability
2Productivity
If a grating coupler is added to the operational optical path for testing, then testing is enabled, but device complexity increases and additional components are required
Solution Approach 1:
By segmenting the optical terminals into separate first and second terminals, the testing path through the grating coupler is isolated from the operational path. This eliminates the need for additional coupling components between the grating coupler and operational terminal, reducing overall device complexity while maintaining testing capability
Solution Approach 2:
The second optical terminal provides a copy or duplicate interface for testing purposes, allowing the grating coupler to couple signals into the photodiode through this secondary terminal rather than requiring direct integration into the operational path. This copying approach simplifies the overall structure by avoiding complex integration schemes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for effective wafer-level testing of photodiodes without damaging the PIC or affecting its later operation, as the grating coupler is in a dedicated path and does not require additional components to couple into the operational path.
Implementation Method 1
a grating coupler in optical communication with the second optical terminal of the photodiode
Data Source
AI summary
A structure for testing a photodiode in a PIC using a grating coupler in optical communication with an optical terminal in a different location of the photodiode from another optical terminal used during operation of the PIC. The photodiode includes an operational optical terminal and a test optical terminal with the test optical terminal in a different location than the operational optical terminal. An optical component is in optical communication with the operational optical terminal of the photodiode and is used during operation of the photodiode and the PIC. A grating coupler is in optical communication with the test optical terminal of the photodiode for testing purposes.