Asymmetrical Photonic Crystal Waveguide for Unidirectional Light Radiation
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Solution Overview
Problem
Traditional photonic crystal waveguides with symmetrical structures suffer from equal upward and downward light radiation, leading to inefficient light utilization and beam distortion, resulting in a 3 dB loss during transmission and reception, and inability to achieve unidirectional radiation efficiency.
Innovation Solution
A photonic crystal waveguide with an asymmetrical cross-sectional shape in the dual-periodic structure, where the low refractive index parts have different diameters or grating pitches, enhancing radiation efficiency by directing light unidirectionally through the asymmetrical design of circular holes and their arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a symmetrical photonic crystal waveguide structure is used, then the structure is simple to manufacture, but light radiates equally in upward and downward directions causing inefficient light utilization and 3 dB loss
Solution Approach 1:
The patent applies asymmetry by designing the photonic crystal waveguide with low refractive index parts having different dimensions in the thickness direction. Specifically, the first low refractive index part has a different size from the second low refractive index part, creating an asymmetric structure that causes light to radiate preferentially in one direction (upward) rather than equally in both directions, thereby improving light utilization efficiency and reducing the 3 dB loss associated with symmetric structures.
2Stability of the object's composition
If a symmetrical photonic crystal waveguide structure is used, then manufacturing is easier, but beam distortion occurs due to equal upward and downward radiation
Solution Approach 1:
The asymmetric structure with low refractive index parts of different sizes suppresses downward radiation and enhances upward radiation, preventing beam distortion caused by equal bidirectional radiation. This maintains beam quality and stability while avoiding the complexities of more sophisticated beam control mechanisms.
3Length of moving object
If traditional mechanical light deflection mechanisms are used, then light deflection is achieved, but the device size is large and cost is increased
Solution Approach 1:
The patent replaces traditional mechanical light deflection mechanisms (such as rotating mirrors or galvanometer-based systems) with a photonic crystal waveguide structure that achieves light deflection through optical principles. The asymmetric photonic crystal structure manipulates light propagation and radiation directions using refractive index differences and periodic structures, eliminating moving parts and reducing device size while maintaining manufacturing feasibility through standard photolithography techniques.
4Shape
If a diffraction grating type light deflection device is used, then sharp beams are formed, but the optical deflection angle is small
Solution Approach 1:
The patent employs local quality by creating regions with different low refractive index part sizes within the photonic crystal waveguide. The first and second low refractive index parts have different dimensions, creating localized variations in optical properties that enable both sharp beam formation and increased deflection angle. This local differentiation allows the structure to achieve high beam quality while expanding the deflection angle range beyond what uniform diffraction gratings can provide.
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 asymmetrical design significantly improves radiation efficiency, allowing for unidirectional radiation, reducing beam distortion, and maintaining high-quality monomodal beam formation, thereby enhancing light utilization and reducing transmission and reception losses.
Implementation Method 1
a photonic crystal waveguide having a lattice array with low refractive index parts periodically arranged in a surface of a high refractive-index member
Implementation Method 2
The low refractive index parts have an asymmetrical cross-sectional shape with reference to a thickness direction in at least either of the first and second periodic arrays of the dual-periodic structure
Data Source
Figure 1A
Figure 1B
Figure 2A~2C
AI summary
In a light deflection device, the radiation efficiency of radiated light beams is to be improved. The light deflection device is configured by a photonic crystal waveguide having a lattice array with low refractive index parts periodically arrayed in a surface of a high refractive-index member. The lattice array has a dual-periodic structure consisting of a first periodic array and a second periodic array which differ from each other in periodic arrangement of the low refractive index parts. A line defect where no low refractive index parts are arrayed constitutes a waveguide core for propagating incident light. The cross section of at least either the first periodic array and the second periodic array constituting the periodic arrays of the dual-periodic structure is asymmetrical in the thickness direction of the low refractive index parts.