Integrated Grating Coupler Photodetector for Selective Light Coupling
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Solution Overview
Problem
Existing photonic chips require improved structures for photodetectors and grating couplers to enhance light coupling efficiency and wavelength selectivity, particularly in data communication and computation systems.
Innovation Solution
A photonic chip structure incorporating a first photodetector with a semiconductor layer and a grating coupler, featuring a waveguide core laterally spaced from the coupler, and a pad with sub-wavelength grooves and segments filled with dielectric material, enabling contra-directional coupling and high wavelength selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional photodetector structures are used, then the device can perform basic light detection, but the coupling efficiency is low and the footprint is large
Solution Approach 1:
The patent merges the grating coupler and photodetector into a single integrated structure where the grating coupler is formed directly adjacent to the photodetector's semiconductor layer. This integration eliminates the need for separate coupling components and reduces the overall footprint while improving coupling efficiency through direct optical path coupling.
Solution Approach 2:
The patent transitions from planar photodetector structures to three-dimensional stacked architectures by positioning the grating coupler in a different spatial layer adjacent to the semiconductor layer. This vertical integration approach reduces the lateral footprint while maintaining or enhancing coupling efficiency through optimized optical path geometry.
2Adaptability or versatility
If conventional grating coupler designs are used, then the structure can be formed, but wavelength selectivity is insufficient
Solution Approach 1:
The patent implements local quality by varying the periodicity, depth, and width of grating structures at different locations within the coupler. These localized modifications enable wavelength-selective coupling without requiring complex external filtering components, as each grating region is optimized for specific wavelength ranges.
Solution Approach 2:
The patent achieves wavelength selectivity by changing physical parameters of the grating structure including period spacing, groove depth, and fill factor. These parameter variations allow the same grating coupler structure to selectively couple different wavelengths, providing adaptability without increasing overall device complexity.
3Reliability
If photodetectors are integrated with grating couplers, then coupling efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by forming the grating coupler structure first, then using it as a reference template for subsequent photodetector alignment. This sequential fabrication approach with built-in registration features ensures precise alignment without requiring post-fabrication adjustment, thereby maintaining high coupling efficiency while managing manufacturing precision requirements.
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
The structure achieves high coupling efficiency and selective wavelength reflection, reducing the footprint compared to traditional designs like Mach-Zehnder interferometers, facilitating compact and efficient data processing.
Implementation Method 1
enabling contra-directional coupling and high wavelength selectivity
Implementation Method 2
first grating coupler may include a plurality of grooves in the pad and a plurality of segments between the plurality of grooves; each groove may be disposed between an adjacent pair of the plurality of segments; the plurality of segments may be dimensioned and positioned to define a sub-wavelength grating
Implementation Method 3
A photodetector may be employed in the photonic integrated circuit to convert light, which may be modulated as an optical signal, into an electrical signal
Implementation Method 4
the plurality of segments may be dimensioned and positioned to define a sub-wavelength grating, and the plurality of grooves may be filled by a dielectric material
Data Source
Figure 1
Figure 2~2A
Figure 2B~3
AI summary
Structures for a photonic chip that include a photodetector and a grating coupler, and methods of forming such structures. The structure comprises a photodetector including a semiconductor layer, and a grating coupler adjacent to the semiconductor layer of the photodetector. The structure further comprises a waveguide core including a portion that is laterally spaced from the grating coupler.