Optical Chip Interrogation Using Shared Grating Couplers
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Solution Overview
Problem
Existing methods for interrogating optical chips face inefficiencies and alignment challenges, particularly in free-space coupling and multiplexed optical sensor systems, where significant chip area is occupied by input and output couplers, leading to wasted light and alignment difficulties.
Innovation Solution
A method and system for interrogating optical chips by illuminating the chip with input light and measuring a spatially resolved image of the output light, including the reflection of the input light spot, to determine the relative positions of input and output ports, allowing for precise alignment and spectral response measurement using a single detector array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If vertical grating couplers are used for input and output, then light coupling efficiency is improved, but chip area occupied by couplers increases and alignment becomes more difficult
Solution Approach 1:
The patent combines input and output ports on the same side of the chip, allowing both functions to share the same grating coupler structures. This merging approach reduces the total chip area required compared to having separate input and output sides, while maintaining efficient vertical coupling for both signal injection and collection.
Solution Approach 2:
The grating couplers are designed to serve dual purposes: functioning as both input couplers for signal injection and output couplers for signal collection. This multi-functionality eliminates the need for separate dedicated input and output grating structures, thereby reducing overall chip area occupation while preserving coupling efficiency.
2Adaptability or versatility
If multiple output couplings are implemented, then sensing capability is improved, but chip area occupied by couplers increases significantly
Solution Approach 1:
The patent transitions from horizontal out-coupling at chip edges to vertical out-coupling through grating structures on the chip surface. This dimensional change allows multiple output channels to be packed more densely in the vertical dimension rather than spreading them out horizontally along chip edges, thereby supporting enhanced sensing capability with reduced chip area occupation.
3Device complexity
If free-space coupling is used, then device complexity is reduced, but alignment precision between input light and input ports becomes more difficult
Solution Approach 1:
The system uses the optical chip itself to generate alignment reference signals. The reflected input light and output light from the chip are imaged onto the detector to automatically indicate the positions of input and output ports, enabling the chip to provide its own alignment guidance without requiring external alignment fixtures or complex positioning mechanisms.
Solution Approach 2:
The imaging system provides real-time feedback by capturing the positions of reflected input light and output light on the detector. This visual feedback allows operators to precisely adjust and align the input light beam with the input ports and verify output coupling, significantly improving alignment precision while keeping the free-space coupling approach simple.
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 approach enhances alignment efficiency and spectral response measurement, optimizing light coupling and reducing the complexity of aligning input and output ports, thereby improving the overall interrogation process of optical chips.
Implementation Method 1
The reflected light can be received by the imaging system and projected in a corresponding location of the image plane, i.e. detector. The location where the reflected input light is detected may thus correlate with the location where the input light was directed onto the optical chip surface.
Implementation Method 2
The imaging system is configured to project an image of the surface onto a detector disposed in a corresponding imaging plane of the imaging system.
Data Source
AI summary
In a method or system for interrogating an optical chip (50), the optical chip (50) is illuminated with input light (30) and a spatially resolved image (50i) of the output light (31,32) is measured from the optical chip (50). The output light (31,32) is imaged together with a reflection of the input light (30). For example, this can be used to establish, improve, or maintain alignment of the input light (30) on a sensor input port (51) of the optical chip (50). The same detector (17) measures the spatially resolved image and a spectral response of the optical chip (50).