Photonic Device On-Wafer Testing via Integrated Diagnostics
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Solution Overview
Problem
Conventional photonic devices lack efficient methods for on-wafer testing, self-calibration, and built-in diagnostics, requiring external loop-back testing and fiber optic cables, which are impractical before dicing and packaging, and do not allow for wafer-level electrical and optical testing of integrated optical elements.
Innovation Solution
A photonics system with integrated transmit and receive waveguides, optical switches, and diagnostics waveguides enables on-wafer testing through self-test capabilities, using variable couplers for optical loopback and on-chip generation of test patterns, allowing for wafer-level probing and calibration of photonic devices without external fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external loop-back testing and fiber optic cables are used for photonic device testing, then testing can be performed, but the method is impractical before dicing and packaging and requires external equipment
Solution Approach 1:
The patent integrates the testing functionality directly into the photonic device by incorporating test waveguides, optical switches, and test receivers onto the same chip as the functional photonic components. This merging eliminates the need for external fiber optic cables and loop-back equipment, enabling self-contained testing that is practical before dicing and packaging.
Solution Approach 2:
The photonic device is designed with built-in self-testing capabilities where the device tests itself using integrated test waveguides and optical switches. The test receiver on-chip detects test signals without requiring external testing equipment, allowing the device to perform self-diagnosis and yield assessment before packaging.
2Reliability
If conventional external testing methods are used, then photonic devices can be tested, but testing time is extended and manufacturing costs increase
Solution Approach 1:
The testing functionality is built into the device structure during fabrication, allowing tests to be performed on the wafer level before dicing and packaging. This preliminary testing action identifies defective devices early in the manufacturing process, eliminating the need for time-consuming post-packaging testing and reducing overall testing time.
Solution Approach 2:
By combining test waveguides, optical switches, and test receivers with the functional photonic components on the same chip, the patent enables direct on-chip testing. This integration eliminates the need for external testing equipment and complex fiber optic connections, significantly reducing testing time and manufacturing costs.
3Productivity
If on-wafer testing is implemented, then testing can be performed before dicing and packaging improving yield, but the device structure becomes more complex
Solution Approach 1:
The patent divides the photonic device into functional segments and dedicated test segments. Test waveguides, optical switches, and test receivers are segregated as separate functional blocks within the overall device structure. This segmentation allows independent testing functionality to be added without fundamentally redesigning the entire photonic device architecture.
Solution Approach 2:
The optical switches in the system serve dual functions: routing signals during normal device operation and directing test signals through the test waveguides during testing. This multi-functionality reduces the need for completely separate test infrastructure, mitigating the increase in structural complexity while enabling on-wafer testing capability.
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
Enables reduced testing time, cost-effective manufacturing, self-calibration, automatic configuration of optical circuits, and on-board diagnostics, facilitating identification of sub-threshold performance before dicing and packaging, thereby improving yield and enabling continuous module health monitoring during operational lifetime.
Implementation Method 1
a transmit waveguide coupled to the transmit photonics module
Implementation Method 2
coupling at least a portion of the optical signal into a diagnostics waveguide to provide a diagnostics signal
Implementation Method 3
coupling at least a portion of the diagnostics signal into a receive waveguide
Implementation Method 4
a receive waveguide coupled to the receive photonics module
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A photonics system includes a transmit photonics module and a receive photonics module. The photonics system also includes a transmit waveguide coupled to the transmit photonics module, a first optical switch integrated with the transmit waveguide, and a diagnostics waveguide optically coupled to the first optical switch. The photonics system further includes a receive waveguide coupled to the receive photonics module and a second optical switch integrated with the receive waveguide and optically coupled to the diagnostics waveguide.