1. What is wafer-level automated edge coupling testing?
Answer: Wafer-level automated edge coupling testing enables photonic chips to be tested on the wafer before dicing. Light coupling and alignment are achieved through the high-precision positioning of fibers or fiber array unit (FAU) in the pre-dicing trench. This wafer-level approach is significantly faster and more cost-effective than testing singulated dies, greatly shortening the R&D lifecycle and boosting the production throughput of photonic chips.
2. What is the difference between edge coupling and grating coupling testing?
Answer: Edge couplers provide significant advantages over grating couplers, including higher coupling efficiency, broader optical bandwidth, and lower polarization dependence. These features make edge couplers the preferred choice for advanced photonic chips, such as optical interposers. However, testing edge-coupled photonic chips at the wafer level is more challenging compared to grating-coupled devices, as precise light coupling must be achieved in a shallow pre-dicing trench on the wafer, along with the added complexity of automating the testing process.
3. Will the trench size affect the wafer’s utilization rate?
Answer: For photonic chips, which are typically millimeter-sized, the impact of trenches on wafer utilization is minimal. Trenches with widths of 250–500 microns and depths of 60-100 microns do not significantly reduce the number of chips on the wafer. In production, these trenches can placed in the "street" areas reserved for dicing. This ensures that the functional regions of the chips remain unaffected, maintaining efficient wafer utilization and optimal chip performance.
4. Will dicing the wafer after edge coupling testing damage the chips?
Answer: The impact of dicing on photonic chips is minor with the use of high-precision dicing techniques such as stealth dicing and adequate clearance is provided between the chip's functional areas.
5. How does automated testing improve production efficiency?
Answer: There are typically hundreds or thousands of photonic chips on a wafer, making manual testing impractical due to the time required for optical alignment, which can take minutes or even hours per chip depending on the equipment used. In contrast, automated testing achieves high-speed optical alignment through high-precision motion control, typically completing an alignment in 3-4 seconds, thus enabling the testing of every individual chip on the wafer.
6. What is the typical coupling efficiency of the automated edge coupling test equipment?
Answer: The coupling efficiency depends on the design of the edge coupler on the photonic chip and the type of fibers used. In wafer-level testing, a reference structure is typically used, often a loopback configuration with edge couplers serving as the input and output ports. The insertion loss measured from this reference structure is then subtracted from the insertion loss of the actual photonic chip tests, ensuring accurate results.
7. How does the system ensure testing precision and consistency?
Answer: Sunyu's PIC Probe Station performs active alignment for each individual photonic chip to compensate for positional offsets due to the wafer warpage and environmental effects on the motion control system.
8. How long does it take to align the fiber probes during testing?
Answer: Sunyu's PIC Probe Station enables high-speed fiber alignment, typically completed within seconds, depending on the complexity of the photonic chip and the test requirements.
9. Is the testing equipment compatible with our existing production line?
Answer: Sunyu's PIC Probe Station supports in-line integration. For more information, we recommend reaching out to discuss your existing production line configurations.
10. What are the maintenance frequency and costs for the equipment?
Answer: Regular maintenance includes cleaning the fiber probes, calibrating the alignment system, and ensuring the overall system is functioning properly. Maintenance is typically required once every 6 to 12 months, and the cost is relatively low. We provide full after-sales support, including remote technical assistance and routine maintenance services to ensure long-term reliability.
11. What is the typical ROI (Return on Investment) for this automated testing equipment?
Answer: The ROI depends on the scale of testing and production efficiency gains. Automated testing significantly reduces manual labor costs and improves throughput, typically allowing the investment to be recovered within 6 months to 2 years. We can help calculate a detailed ROI based on your specific production requirements.
12. Does the system support future upgrades?
Answer: Yes, the system is highly flexible and expandable. We offer hardware and software upgrade services to meet your future needs, ensuring the equipment can keep pace with advancements in testing technology and new product requirements.