Tunable Pitch Optical Grating via Neutral Dielectric LC Mixture
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Solution Overview
Problem
Existing diffractive optical elements using liquid crystals have fixed pitch diffraction structures, making their diffraction angles non-adjustable, which complicates their manufacture and increases costs.
Innovation Solution
A liquid crystal mixture with a neutral net dielectric anisotropy is developed, comprising a host LC and LC dimers with opposite dielectric anisotropies, allowing for electrically continuous adjustment of pitch and diffraction angles through flexoelectric domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional electrically switchable diffractive optical elements using LCs with fixed pitch structures are used, then the manufacturing process is complicated and expensive, but the pitch and diffraction angle cannot be electrically adjusted
Solution Approach 1:
The patent changes the dielectric anisotropy parameter of the LC mixture by combining host LC molecules with positive dielectric anisotropy and LC dimer molecules with negative dielectric anisotropy. This creates a mixture with substantially neutral net dielectric anisotropy, enabling the LC molecules to form flexoelectric domains that can be electrically controlled to adjust pitch and diffraction angle continuously, thereby achieving adaptability without complex manufacturing
Solution Approach 2:
The patent uses a composite LC mixture consisting of host LC molecules and LC dimer molecules with opposite dielectric anisotropies. This composite material exhibits flexoelectric effect that enables electrical control of the diffraction grating pitch, simplifying the device structure while achieving tunable diffraction angles
2Adaptability or versatility
If LC mixtures with non-neutral dielectric anisotropy are used, then the LC molecules align uniformly under electric field, but flexoelectric domains cannot be formed for pitch adjustment
Solution Approach 1:
The patent specifically adjusts the dielectric anisotropy parameter of the LC mixture to be substantially neutral by carefully selecting the ratio of host LC molecules (positive dielectric anisotropy) to LC dimer molecules (negative dielectric anisotropy). This parameter change enables the formation of flexoelectric domains under applied electric field while maintaining reliable LC molecule alignment, achieving both adaptability and reliability
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
Enables electrically tunable pitch and diffraction efficiency in optical devices, simplifying manufacturing and reducing costs by allowing continuous adjustment of diffraction angles.
Implementation Method 1
allowing for electrically continuous adjustment of pitch and diffraction angles through flexoelectric domains
Implementation Method 2
The host LC and the one or more LC dimers have respective dielectric anisotropies of opposite signs in nematic phase. A net dielectric anisotropy of the LC mixture is substantially neutral at a predetermined temperature.
Data Source
AI summary
An optical device is provided. The optical device includes an optical grating. The optical grating includes two electrodes arranged opposite to each other and a liquid crystal (LC) composition sandwiched between the electrodes. The two electrodes provide a driving voltage to the optical grating. The LC mixture includes a host LC and one or more LC dimers dissolved as a guest in the host LC. The host LC and the one or more LC dimers have respective dielectric anisotropies of opposite signs in nematic phase. A net dielectric anisotropy of the LC mixture is substantially neutral at a predetermined temperature.