Optical Grating Coupling for Reduced Chip Size
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Solution Overview
Problem
The challenge of reducing signal loss and increasing routing possibilities in semiconductor chips while minimizing their size is exacerbated by the need for larger openings or cavities due to the angle and divergence of optical fibers relative to standard optical gratings, which limits the ability to reduce chip dimensions.
Innovation Solution
Implementing optical gratings with variable geometric properties, such as variations in pitch, depth, and width, to effectively couple optical signals between chips and optical fibers even when the fiber is positioned close to normal from the grating surface, thereby reducing the size of the opening in the interconnect structure and enhancing routing possibilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the angle between the optical grating and the optical fiber is increased to improve coupling efficiency, then signal loss is reduced, but the cavity dimension increases leading to increased chip size
Solution Approach 1:
The patent applies parameter changes by varying the pitch, depth, and width of the grating features to optimize the coupling angle. By adjusting these geometric parameters, the system achieves effective coupling at smaller angles (closer to normal incidence), which reduces the required cavity dimension and thereby minimizes chip size while maintaining low signal loss.
Solution Approach 2:
The patent implements local quality by creating non-uniform grating structures where different regions have different pitch, depth, or width characteristics. This allows localized optimization of the coupling properties in different areas of the grating, enabling effective coupling at smaller angles without requiring uniform large-angle coupling across the entire structure, thus reducing the overall cavity dimension.
2Loss of energy
If the cavity dimension is increased to reduce signal loss, then coupling efficiency is improved, but routing possibilities are reduced
Solution Approach 1:
By changing the grating parameters (pitch, depth, width) to enable effective coupling at smaller angles, the system reduces the cavity dimension. This smaller cavity allows for more routing paths and better adaptability in the chip interconnect structure without sacrificing coupling efficiency.
Solution Approach 2:
The patent explores different dimensional configurations of the grating structure by varying pitch, depth, and width independently. This multi-dimensional parameter space allows for optimization of coupling efficiency at smaller angles, thereby reducing the cavity dimension and freeing up routing space in the chip.
3Ease of manufacture
If standard optical gratings are used with fixed geometric properties, then manufacturing is simpler, but coupling efficiency at small angles is insufficient
Solution Approach 1:
The patent introduces local variations in grating properties (different pitch, depth, or width in different regions) to enhance coupling efficiency at small angles. While this increases manufacturing complexity compared to uniform gratings, it enables significantly reduced signal loss, and the variations can be implemented using standard semiconductor manufacturing techniques.
Solution Approach 2:
The patent creates a dynamic or adjustable grating structure where parameters like pitch, depth, or width can be varied to optimize coupling for different operating conditions. This dynamic capability allows the grating to adapt to different coupling angles and signal requirements, improving efficiency while maintaining manufacturability through programmable or configurable structures.
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 allows for reduced chip size and maximized routing possibilities by efficiently coupling optical signals with minimal signal loss, even when the optical fiber is nearly perpendicular to the grating, thus addressing the limitations of standard gratings.
Implementation Method 1
The grating is configured to redirect the optical signal at a substantially 90-degree angle into the waveguide layer
Implementation Method 2
an optical fiber... configured to transmit an optical signal
Data Source
AI summary
A coupling system includes a chip configured to receive an optical signal, wherein an angle between a propagation direction of the optical signal and a top surface of the chip ranges from about 92-degrees to about 88-degrees. The chip includes a grating configured to receive the optical signal; and a waveguide, wherein the grating is configured to receive the optical signal and redirect the optical signal along the waveguide, and the grating is on a light incident side of the waveguide.