Twisted Liquid Crystal Optical Element for Guided-Mode Resonance
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Solution Overview
Problem
Optical elements using liquid crystal diffraction elements for guided-mode resonance exhibit a narrow reflection wavelength range and insufficient controllability, limiting their application in optical sensors and filters.
Innovation Solution
A liquid crystal optical element with a twisted and aligned structure, where the liquid crystal compound's optical axis rotates continuously in one in-plane direction and is twisted in the thickness direction, enhancing the reflection wavelength range and controllability by adjusting the twisted angle between 10° to 120°, and immobilizing the cholesteric liquid crystalline phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a liquid crystal diffraction element with continuously rotating optical axis is used for guided-mode resonance, then the optical element can be easily manufactured, but the reflection wavelength range becomes narrow and controllability is insufficient
Solution Approach 1:
The patent applies parameter changes by introducing a twisted angle parameter (10° to 120°) in the thickness direction of the liquid crystal layer. This twisted angle, combined with the in-plane rotation, creates a new degree of freedom for controlling the reflection wavelength range. By adjusting this parameter, the patent achieves both ease of manufacture (maintaining liquid crystal material simplicity) and improved controllability (through enhanced wavelength range adjustment capability).
Solution Approach 2:
The patent transitions from a two-dimensional in-plane rotation model to a three-dimensional structure by adding rotation in the thickness direction. This dimensional extension creates a more complex spatial distribution of the optical axis, which provides additional control mechanisms for the reflection wavelength range while maintaining the ease of liquid crystal fabrication processes.
2Reliability
If the liquid crystal layer is configured to guide light with sandwiched structure, then guided-mode resonance can occur, but the reflection wavelength range remains narrow
Solution Approach 1:
The patent introduces dynamic control capability by enabling adjustment of the twisted angle parameter, which allows the reflection wavelength range to be tuned. This dynamic adjustment mechanism, combined with the guided-mode resonance structure, provides both reliable resonance occurrence and flexible wavelength range control, resolving the contradiction between structural stability and operational flexibility.
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 solution widens the reflection wavelength range and improves controllability, allowing for more precise wavelength selection and sensitivity in optical sensors, enabling applications such as refractive index measurement and biochemical sensing.
Implementation Method 1
light in a specific wavelength range is guided while being repeatedly reflected
Implementation Method 2
light in a specific wavelength range is guided while being repeatedly reflected, and thus resonance occurs. As a result of the occurrence of the resonance, the light having the specific wavelength is strongly emitted as reflected light
Data Source
AI summary
Provided are an optical element that causes a guided-mode resonance phenomenon to occur using a liquid crystal diffraction element to reflect light in a specific wavelength range such that the reflection wavelength range can be widened and the controllability of the width of the reflection wavelength range is also excellent, and an optical sensor including the above-described optical element. The optical element includes a liquid crystal layer that is formed of a composition including a liquid crystal compound, in which the liquid crystal layer has a liquid crystal alignment pattern in which a direction of an optical axis derived from the liquid crystal compound changes while continuously rotating in at least one in-plane direction, the liquid crystal compound is twisted and aligned in a thickness direction, and the liquid crystal layer further has a resonance structure.