Curved Waveguide Bend Suppressing Mode Conversion
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Solution Overview
Problem
Waveguide bends in photonic integrated circuits often cause mode conversion to higher order modes, leading to performance degradation and increased size, which is undesirable in high-density optical communication systems.
Innovation Solution
The use of a bend section with a curvature function, such as a sinusoidal or Dolph-Chebyshev function, to suppress waveguide mode conversion, reducing the size of the waveguide while maintaining performance by minimizing higher order mode coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional waveguide bend is used to route optical signals, then the waveguide can be routed around corners, but mode conversion to higher order modes occurs causing performance degradation
Solution Approach 1:
The patent applies curvature by designing the waveguide bend with a specific curved geometry where the bend radius varies along the propagation direction. This controlled curvature distributes the bending stress more uniformly, preventing abrupt mode conversions while maintaining the ability to route optical signals around corners.
Solution Approach 2:
The patent changes geometric parameters of the waveguide bend, specifically varying the bend radius as a function of position along the waveguide. This parameter variation optimizes the bend to minimize mode conversion while maintaining compact routing, achieving both ease of operation and signal quality.
2Reliability
If the waveguide bend radius is increased to reduce mode conversion, then optical signal quality improves, but the waveguide size increases
Solution Approach 1:
The patent employs parameter changes by defining the bend radius as a position-dependent function rather than a constant value. This allows the waveguide to achieve low mode conversion with a more compact overall size, as the radius varies optimally along the propagation path rather than requiring uniform large radius throughout.
Solution Approach 2:
The patent uses controlled curvature variation along the waveguide path to achieve compact bending while maintaining signal quality. The curvature is optimized to provide sufficient radius where needed to prevent mode conversion while minimizing the overall bend footprint.
3Device complexity
If a standard circular bend is used, then the waveguide layout is simple, but higher order mode coupling increases causing performance degradation
Solution Approach 1:
The patent modifies the geometric parameters of the bend by transitioning from a constant radius circular arc to a variable radius curve. This parameter change maintains reasonable design simplicity while dramatically improving mode conversion suppression through optimized curvature distribution.
Solution Approach 2:
The patent replaces the simple circular curvature with a more sophisticated variable curvature profile. This maintains the intuitive curved shape for layout simplicity while the varying radius optimizes the bending to prevent higher order mode coupling.
Data Source
AI summary
A photonic integrated circuit may include a substrate and an optical waveguide integrated with the substrate. The optical waveguide may include a bend section, wherein a bend shape of the bend section is defined by a curvature function to suppress waveguide mode conversion.