Jagged Diagonal Polarization Converter Core
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Solution Overview
Problem
Current polarization converters face a challenge in improving coupling efficiency while maintaining a compact converter length, as increasing the asymmetry of the core part's cross-sectional shape to enhance phase difference between electromagnetic wave modes leads to decreased coupling efficiency at the boundaries.
Innovation Solution
A polarization converter with a core part featuring a cross-sectional shape cut along a jagged diagonal line, which reduces surface roughness to enhance coupling efficiency without significantly increasing converter length, by maintaining a balance between propagation constant differences and light distribution matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the asymmetry of the cross-sectional shape of the asymmetric core part is increased to reduce the converter length, then the difference in propagation constants increases and the converter length decreases, but the coupling efficiency at the boundaries decreases
Solution Approach 1:
The diagonal line of the asymmetric core part is segmented into multiple small steps (first diagonal line segment, second diagonal line segment, third diagonal line segment) rather than being a single continuous line. This segmentation allows the structure to maintain asymmetry for phase difference while reducing surface roughness at boundaries to improve coupling efficiency
Solution Approach 2:
Different regions of the asymmetric core part have different properties: the overall shape maintains asymmetry for phase difference, while the boundary regions use stepped segments with reduced surface roughness to improve coupling efficiency. The local structure is optimized for different functions at different locations
2Volume of moving object
If the converter length is reduced to improve compactness, then the device size decreases, but the coupling efficiency at boundaries decreases due to increased asymmetry
Solution Approach 1:
The diagonal boundary is divided into multiple stepped segments that reduce surface roughness at the boundaries. This allows the converter to maintain a compact size while improving the light distribution matching at input and output boundaries, thereby maintaining coupling efficiency
Solution Approach 2:
The diagonal line is transformed from a continuous 2D line into a stepped 3D structure with multiple levels. This dimensional transformation allows the boundary to have reduced surface roughness in the optical propagation direction while maintaining the overall asymmetry needed for phase difference
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 jagged diagonal line design improves coupling efficiency at the input and output boundaries, allowing for efficient polarization state conversion with a shorter converter length, as demonstrated by simulation results showing increased efficiency with minimal length growth.
Implementation Method 1
When the electromagnetic wave is incident onto the asymmetric core part 95c, two polarization modes in diagonal directions that are orthogonal to each other are generated. Because of the asymmetry of a cross-sectional shape of the asymmetric core part 95c, a propagation constant (wave number) β1 of an electromagnetic wave of a first mode and a propagation constant (wave number) β2 of an electromagnetic wave of a second mode are different.
Implementation Method 2
a dielectric waveguide (see also FIGS. 1 and 2 of the present application)... The core parts 95a, 95b, 95c have a substantially cuboidal shape... An electromagnetic wave is incident onto the incident side core part 95a, passes through the asymmetric core part 95c, and is emitted from the emitting side core part 95b.
Data Source
AI summary
A polarization converter of the invention includes a core part that wave-guides an electromagnetic wave and a cladding part that is provided around the core part. The core part includes a conversion part converting a polarization state of the electromagnetic wave. A cross-sectional shape of the conversion part in a plane orthogonal to a propagation direction of the electromagnetic wave is a shape formed by cutting off a portion of a rectangular or square shape along a jagged diagonal line.