Optical Waveguide Tapered Bend Design for Low-Loss Compact Circuits
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Solution Overview
Problem
Existing optical waveguide circuits face challenges in minimizing circuit excess loss while maintaining a small curvature radius, which leads to increased bend radiation loss. Additionally, connecting waveguides with different widths and curvatures results in significant waveguide connection losses.
Innovation Solution
The proposed optical waveguide configuration includes a straight waveguide connected to a tapered waveguide bend, which is then connected to a waveguide bend with a larger curvature radius. The waveguide widths are optimized such that the waveguide width of the tapered waveguide bend changes continuously from the straight waveguide to the waveguide bend, and the optical axes are offset to maximize the overlap integral of the electric field distributions, thereby reducing losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the curvature radius of the waveguide bend is reduced to decrease the circuit area, then the circuit area is reduced, but the bend radiation loss increases
Solution Approach 1:
The patent changes the waveguide width parameter along the propagation direction to optimize the balance between circuit area and bend radiation loss. By adjusting the waveguide width in the bend region, the mode field distribution is controlled to reduce radiation loss while maintaining a compact curvature radius
Solution Approach 2:
The patent applies different waveguide widths at different locations: a first waveguide width in the input straight waveguide, a second (larger) waveguide width in the waveguide bend, and a third waveguide width in the output straight waveguide. This local optimization allows the bend region to have enhanced light confinement while keeping overall circuit area small
2Device complexity
If waveguides with different widths and curvatures are connected directly, then the circuit structure is simplified, but the waveguide connection loss increases
Solution Approach 1:
The patent introduces an intermediary tapered waveguide section between the input straight waveguide and the waveguide bend. This tapered section acts as a transition zone that gradually transforms the mode field distribution, reducing the abrupt mismatch and thereby minimizing connection loss while adding minimal structural complexity
3Loss of energy
If the waveguide width is increased to reduce bend radiation loss, then the bend radiation loss is reduced, but the circuit area increases
Solution Approach 1:
The patent divides the waveguide structure into distinct segments with different widths: the input straight waveguide section, the waveguide bend section, and the output straight waveguide section. Each segment is optimized independently for its specific function, allowing the bend region to have larger width for reduced radiation loss while other regions maintain smaller dimensions
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 configuration achieves low-loss waveguide bends with small curvature radii, reducing circuit excess loss and waveguide connection loss while maintaining a compact circuit area. The optimized waveguide widths and offset connections effectively minimize bend radiation loss and different-curvature waveguide connection loss.
Implementation Method 1
a waveguide width of the waveguide bend is larger than a waveguide width of the straight waveguide at a connection point, the optical waveguide includes a tapered waveguide bend inserted between the straight waveguide and the waveguide bend
Implementation Method 2
the tapered waveguide bend and the straight waveguide are connected with an optical axis of the tapered waveguide bend and an optical axis of the straight waveguide being offset such that a square of an absolute value of an overlap integral of a normalized electric field distribution of a fundamental propagation mode
Data Source
AI summary
A waveguide bend which has low loss while keeping the curvature radius small in a waveguide with a given A is realized. An optical waveguide has a straight waveguide and a waveguide bend connected to each other, and tapered waveguide bends inserted between the straight waveguide and the waveguide bend, a curvature radius of the tapered waveguide bend being equal to a curvature radius of the waveguide bend, a waveguide width of the tapered waveguide bend changing continuously from the waveguide width of the straight waveguide at the connection point to the waveguide width of the waveguide bend. A waveguide width of the waveguide bend is larger than a waveguide width of the straight waveguide at a connection point and the tapered waveguide bend and the straight waveguide are connected with an optical axis of the tapered waveguide bend and an optical axis of the straight waveguide being offset.