Trapezoidal Pillar Waveguide Bend for Low-Loss Routing
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Solution Overview
Problem
Subwavelength photonic crystal waveguide bends suffer from high loss and large bend radius limitations, which hinder the development of integrated photonic systems and high-quality factor ring resonators for optical modulators, switches, and sensors.
Innovation Solution
A trapezoidal shaped dielectric pillar based subwavelength photonic crystal waveguide bend is introduced, allowing control of the refractive index profile to reduce bend loss by shifting the mode back to the center, thereby minimizing phase front distortion and radiation loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If subwavelength photonic crystal waveguide bends are used to achieve compact integrated photonic systems, then the bend radius is reduced and device integration is improved, but the insertion loss increases significantly
Solution Approach 1:
The patent applies local quality by varying the transverse profile of dielectric pillars along the waveguide bend. The pillar width transitions from narrower at the inner radius to wider at the outer radius, creating a refractive index gradient that locally compensates for mode delocalization effects. This localized structural modification enables the waveguide to maintain mode confinement throughout the bend, reducing radiation loss while achieving compact routing.
Solution Approach 2:
The patent implements parameter changes by systematically varying the geometric parameters of the dielectric pillars along the bend path. Specifically, the pillar width parameter is continuously adjusted as a function of position along the bend, creating a tapered profile that modifies the effective refractive index distribution. This parameter variation compensates for the changing modal characteristics in the bend, maintaining low loss throughout the structure.
2Loss of energy
If conventional strip waveguides are used for bends to reduce loss, then insertion loss is minimized, but additional tapers are required which waste chip surface area
Solution Approach 1:
The patent extracts the tapering function from a separate structural element and integrates it directly into the dielectric pillar geometry of the waveguide bend itself. By incorporating the width variation directly into the pillar structure along the bend path, the design eliminates the need for separate taper sections, thereby reducing the overall device footprint while maintaining low loss performance.
Solution Approach 2:
The patent merges the bend function and the mode adaptation function into a single integrated structure. The dielectric pillar width variation along the bend simultaneously achieves both the geometric curvature required for bending and the gradual mode transformation needed to minimize radiation loss, combining multiple functions into one compact element.
3Adaptability or versatility
If subwavelength photonic crystal waveguides are used to enhance photon-matter interaction, then control over waveguide properties is improved, but bend loss increases due to mode delocalization
Solution Approach 1:
The patent applies local quality by varying the transverse profile of dielectric pillars along the waveguide bend. The pillar width transitions from narrower at the inner radius to wider at the outer radius, creating a refractive index gradient that locally compensates for mode delocalization effects. This localized structural modification enables the waveguide to maintain mode confinement throughout the bend, reducing radiation loss while achieving compact routing.
Solution Approach 2:
The patent implements parameter changes by systematically varying the geometric parameters of the dielectric pillars along the bend path. Specifically, the pillar width parameter is continuously adjusted as a function of position along the bend, creating a tapered profile that modifies the effective refractive index distribution. This parameter variation compensates for the changing modal characteristics in the bend, maintaining low loss throughout the structure.
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 trapezoidal shaped pillars significantly reduce bend loss and enhance the quality factor of subwavelength ring resonators, enabling more efficient optical systems with improved performance in modulators, switches, and sensors.
Implementation Method 1
the equivalent refractive index of the subwavelength photonic crystal waveguide is relatively small so that the bending loss cannot be ignored. With the trapezoidal shaped dielectric pillars, the equivalent refractive index along the radial direction can be controlled to shift the mode back to the center of the subwavelength photonic crystal waveguide
Data Source
AI summary
A method for reducing loss in a subwavelength photonic crystal waveguide bend is disclosed. The method comprising: forming the subwavelength photonic crystal waveguide bend with a series of trapezoidal shaped dielectric pillars centered about a bend radius; wherein each of the trapezoidal shaped dielectric pillars comprise a top width, a bottom width, and a trapezoid height; wherein the length of the bottom width is greater than the length of the top width; and wherein the bottom width is closer to the center of the bend radius of the subwavelength photonic crystal waveguide bend than the top width. Other embodiments are described and claimed.