Wafer-Level Laser Testing via Optical Tap and Photodetector
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Solution Overview
Problem
Current wafer-level laser testing in photonics chips faces inaccuracies due to power measurement variations and the risk of damage from reverse reflection, necessitating improved structures and methods for accurate and reliable testing.
Innovation Solution
A photonics chip structure incorporating a first waveguide, a second waveguide, an optical tap, and a photodetector, with a laser attached to direct and measure laser light, allowing for controlled power increase and accurate optical power measurement without damaging the laser, using optical taps and a grating coupler for spectrum testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current wafer-level testing techniques are used, then testing can be performed at wafer level, but measurement accuracy is limited and reverse reflection may damage the laser
Solution Approach 1:
An optical tap is introduced as an intermediary component that couples the first waveguide to the second waveguide, allowing a portion of the laser light to be diverted to the photodetector for measurement. This mediator enables accurate power measurement while preventing direct reverse reflection to the laser, thus resolving both the measurement accuracy and laser protection requirements
Solution Approach 2:
The optical path is segmented into multiple waveguides (first waveguide, second waveguide) with an optical tap coupling them. This segmentation allows the laser light to be divided, with part going to the photodetector for measurement and part continuing through the system, enabling non-intrusive measurement that doesn't expose the laser to damaging reverse reflections
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 fast and reliable wafer-level testing of lasers with improved accuracy and reduced risk of damage, facilitating the selection of Known Good Die for subsequent packaging and ensuring reliable characterization and qualification of photonics chips.
Implementation Method 1
an optical tap coupling the first waveguide to the second waveguide
Implementation Method 2
a photodetector coupled to the second waveguide... measuring a second electrical current generated by the photodetector in response to the portion of the laser light
Data Source
AI summary
Structures for a photonics chip, testing methods for a photonics chip, and methods of forming a structure for a photonics chip. A photonics chip includes a first waveguide, a second waveguide, an optical tap coupling the first waveguide to the second waveguide, and a photodetector coupled to the second waveguide. A laser is attached to the photonics chip. The laser is configured to generate laser light directed by the first waveguide to the optical tap.