Liquid Crystal Composite Birefringence Modulation
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Solution Overview
Problem
Tuneable spectrum, intensity, and phase modulation devices, such as liquid crystals, face issues like strong incidence angle and polarization dependence, slow speed, and narrow tuning range, which hinder their practical implementation in various field systems, particularly in privacy windows and optical telecommunications.
Innovation Solution
A liquid crystal composite device with porous microparticles infiltrated by the liquid crystal, where the microparticles have an average refractive index matching one of the liquid crystal's principal refractive indices, allowing for polarisation-independent light modulation by tuning the refractive index mismatch with external fields, and optimizing microparticle concentration for contrast and scattering control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional liquid crystal devices are used for light modulation, then spectral filtering and intensity modulation capabilities are achieved, but strong polarization dependence and narrow tuning range occur
Solution Approach 1:
The patent employs a composite structure consisting of liquid crystal molecules combined with porous microparticles. This composite approach allows the device to achieve both spectral filtering capabilities and polarization independence simultaneously. The microparticles with refractive index matching one of the liquid crystal's principal refractive indices create effective index matching in one orientation while maintaining birefringence in another, thus resolving the contradiction between adaptability and polarization dependence.
Solution Approach 2:
The device utilizes external fields (electric, magnetic, thermal, or optical) to dynamically change the refractive index parameters of the liquid crystal composite. By tuning these parameters, the device achieves wide spectral tuning range while maintaining polarization independence through the microparticle-induced index matching effect.
2Productivity
If conventional liquid crystal devices are used for light modulation, then spectral filtering is achieved, but slow response speed occurs
Solution Approach 1:
The incorporation of porous microparticles in the liquid crystal composite creates a structure that enhances the response speed. The porous structure allows for faster reorientation of liquid crystal molecules under external fields, reducing the response time while maintaining the spectral filtering capability. The microparticles act as nucleation sites that facilitate faster molecular alignment.
3Illumination intensity
If microparticle concentration is increased to provide optimum contrast, then scattering performance improves, but significant light scattering occurs for spectrum/phase/polarisation modulation applications
Solution Approach 1:
The patent applies local quality by optimizing the microparticle concentration according to the specific application. For scattering devices, a higher concentration (0.1%-50%) provides optimum contrast, while for spectrum/phase/polarisation modulators, a lower concentration (<0.1%) avoids significant light scattering. This localized optimization resolves the contradiction between light throughput and scattering effects.
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 enables fast, polarization-independent light modulation with improved light throughput and extended tuning range, reducing the cost and inefficiency of privacy windows and enhancing performance in photonic applications.
Implementation Method 1
spectral and phase modulation tunable birefringence devices
Implementation Method 2
refractive index mismatch between said microparticles and said liquid crystal is tuned by applying an external electric or magnetic field
Implementation Method 3
said porous microparticles have an average refractive index approximately equals to one of the liquid crystal principal refractive indices
Implementation Method 4
concentration of said microparticles in said composite is in the range of 0.1%-50% for providing optimum contrast of the device upon switching it between different orientational states
Implementation Method 5
spectral and phase modulation tuneable devices
Implementation Method 6
intensity modulation, polarisation control
Data Source
AI summary
The present invention describes a liquid crystal composite tuneable device for fast polarisation-independent modulation of an incident light beam comprising: (a) two supporting and functional panels, at least one of them coated with a transparent conductive electrode layer and with optionally at least one additional layer selected from an alignment layer, antireflective coating layer, thermochromic or electrochromic layer, photoconductive or photosensitive layer, and (b) a composite structure sandwiched between said two panels and made of a liquid crystal and porous microparticles infiltrated with said liquid crystal. The porous microparticles have an average refractive index approximately equals to one of the liquid crystal principal refractive indices, matching that of the liquid crystal at one orientational state (for example, parallel n∥), and exhibiting large mismatch at another orientational state (for example, perpendicular n⊥). This refractive index mismatch between said microparticles and said liquid crystal is tuned by applying an external electric or magnetic field, thermally or optically.