Variable-Curvature Bent Waveguide for Low-Loss Multimode Routing
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Solution Overview
Problem
Silicon waveguides face challenges with high propagation loss and inter-mode crosstalk in bent waveguides, particularly when designed for multimode conditions, which affect optical communication devices' performance.
Innovation Solution
A bent waveguide design where the curvature radius varies gradually from a first to a second value, with a curvature differential coefficient of zero at the ends, using specific mathematical curves (sine half-wavelength, sine, quadratic function, and linear function) to minimize inter-mode crosstalk and optical loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the bending radius is increased to reduce optical loss, then optical loss is reduced, but the circuit size increases
Solution Approach 1:
The waveguide employs a curved geometry with continuously varying curvature radius, transitioning from a first curvature radius at the input end to a second curvature radius at the output end. This curved path allows the waveguide to achieve compact routing while maintaining low optical loss through optimized curvature variation, resolving the contradiction between small circuit size and low optical loss.
Solution Approach 2:
The invention changes the curvature radius parameter along the waveguide length, transitioning from a first curvature radius to a second curvature radius. This parameter variation optimizes the balance between bending loss and circuit compactness, allowing the waveguide to achieve both small footprint and low optical loss by carefully controlling how the curvature radius changes along the propagation path.
2Object-generated harmful factors
If a wider waveguide is used to reduce inter-mode crosstalk, then inter-mode crosstalk is reduced, but the single-mode condition cannot be satisfied
Solution Approach 1:
The waveguide width is varied along its length, with the width at the input end being different from the width at the output end. This local variation in width allows the waveguide to maintain single-mode operation at critical sections while reducing inter-mode crosstalk in other sections, achieving both requirements through spatially differentiated properties.
Solution Approach 2:
The waveguide transitions from a static, uniform width design to a dynamic design where the width changes along the propagation direction. This dynamic width variation allows the waveguide to adapt its mode confinement characteristics along the path, maintaining single-mode operation where needed while minimizing crosstalk in bending sections.
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 proposed waveguide design achieves low optical loss and inter-mode crosstalk, enabling a smaller footprint and improved device performance by suppressing radiation and reflection, even under multimode conditions.
Implementation Method 1
A silicon waveguide has a large difference between relative refractive indices of the core and the cladding, and can confine light in a minute region
Implementation Method 2
can confine light in a minute region
Data Source
AI summary
An optical waveguide of the present disclosure proposes a configuration of a bent waveguide having a novel configuration. For proposed four types of curves A, B, C, and D, a value obtained by differentiating a curvature along a waveguide is 0 at one end 1=0 and the other end 1=L of a bent waveguide. It is possible to suppress optical loss and inter-mode crosstalk occurring in the bent waveguide. Even in a bent waveguide having a waveguide width under a multimode condition, excellent inter-mode crosstalk characteristics and low loss are achieved as compared with the clothoid curve of the prior art.