Waveguide Coupling Interface With Periodic Structures for Low-Loss Sealing
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Solution Overview
Problem
Existing coupling interfaces for waveguide structures, such as those using glass wafer bonded to a metal layer on a silicon wafer, are expensive and prone to leakage, leading to inefficiencies in signal propagation and increased manufacturing costs.
Innovation Solution
A coupling interface is formed with three-dimensional periodic structures on a substrate, which includes self-terminating, subwavelength periodic structures and blocking structures to reduce the effective dielectric constant, allowing for low-loss signal propagation and hermetic sealing to prevent leakage, using silicon-to-silicon bonding techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass wafer is bonded to a metal layer on a silicon wafer to form a coupling interface, then the waveguide structure can be formed, but the manufacturing cost increases and leakage occurs
Solution Approach 1:
The patent uses silicon-to-silicon bonding to create a homogeneous structure where the substrate material matches the bonding material. This eliminates the need for heterogeneous material combinations (glass-to-metal-on-silicon) and achieves both hermetic sealing and cost reduction through material uniformity and simplified processing.
2Reliability
If glass wafer is bonded to a metal layer on a silicon wafer to form a coupling interface, then the waveguide structure can be formed, but signal leakage increases
Solution Approach 1:
By using silicon substrate for both the waveguide and bonding layers, the patent achieves homogeneous material composition that ensures hermetic sealing and prevents signal leakage, while simplifying the manufacturing process by eliminating multiple material deposition and bonding steps.
3Productivity
If traditional coupling interface is used, then the waveguide can be formed, but impedance mismatch occurs leading to transmission loss
Solution Approach 1:
The patent extracts and eliminates the complex multi-layer coupling interface structure (glass and metal layers) by using direct silicon-to-silicon bonding. This simplification removes the source of impedance mismatch while maintaining waveguide functionality, thereby improving signal transmission efficiency.
Solution Approach 2:
The homogeneous silicon-based structure eliminates dielectric discontinuities and impedance mismatches that occur in heterogeneous material interfaces, enabling efficient signal transmission without complex interface design.
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 solution reduces manufacturing costs and improves transmission efficiency into the cavity by minimizing leakage and impedance mismatch, enabling low-loss signal propagation and integration with additional circuitry on the wafer.
Implementation Method 1
The coupling interface includes three-dimensional periodic structures formed in a first surface of the substrate. The periodic structures reduce an effective dielectric constant of the substrate.
Implementation Method 2
bonding the second substrate to the second surface of the first substrate to form a seal around the cavity
Data Source
AI summary
In a described example, an apparatus includes a first substrate having a first side, a second side, and a coupling interface across a portion of the first side. The coupling interface including an arrangement of subwavelength periodic structures formed in the first substrate. A second substrate is coupled to a portion of the second side of the first substrate to form a sealed cavity aligned with the coupling interface.