Liquid crystal superstructure sensing equipment based on electromagnetic induction absorption

Abstract

A liquid crystal superstructure sensing device based on electromagnetic induction absorption comprises metal layers on the two sides and a periodic structure in the middle. The structure is mainly divided into two parts, the first part is composed of a layer of metal silver and becomes a so-called bright mode in electromagnetic induction absorption, the second part is composed of a dielectric medium and liquid crystals which are periodically arranged, and a layer of metal silver is additionally arranged at the end of the structure and forms a dark mode in electromagnetic induction absorption. When the two parts of the structure are combined together, the electromagnetic induction absorption effect can be formed. According to the invention, the formed electromagnetic induction absorption effect is doped with the liquid crystal, so that the liquidity of the liquid crystal can be utilized to sense a liquid solution, the effect of a refractive index sensor can be realized, and the refractive index sensor has the excellent characteristics of large measurement range, high sensitivity and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic induced absorption, and specifically is a liquid crystal metamer sensing device based on electromagnetic induced absorption. Background Art

[0002] The electromagnetically induced absorption effect, which is centered on the three-level system and the double-oscillator theory, refers to the phenomenon that in a specific atomic or quantum system, the absorption of light by an originally transparent or weakly absorbing medium is enhanced by the action of an external coherent light field. This system may play a vital role in many applications and has great potential and prospects in the fields of optical detection, biosensing, etc.

[0003] Electromagnetic induced absorption has a wide range of important practical uses in many fields, and its application in sensors provides new technical means and solutions for precise measurement and detection. Electromagnetic induced absorption technology can be used for refractive index and defect detection, especially for monitoring the structural integrity and quality control of devices. By analyzing the absorption characteristics of materials under electromagnetic fields, sensors can identify sensors and biological cells with different refractive indices, which is of great value in high-precision sensors.

[0004] After searching, it was found that the Chinese patent with publication number CN114062316B disclosed a high-quality optical refractive index sensor based on a plasmon nanocavity on April 19, 2024. It realizes a resonance peak through the surface plasmon effect and realizes the sensing function of high quality factor. This patent improves the problem of loss in metal radiation and has the ability of fast, quantitative, low-cost and label-free analysis.

[0005] It can be seen that the current optical sensors mainly use the resonance effect such as surface plasmon to excite the resonance peak to form high absorption for detection. However, the excitation principle of the resonance peak is relatively simple and single, and there will be mixed peaks, which will affect the judgment. Some sensors such as surface plasmon resonance excitation have a large active area and are not suitable for molecular detection. Summary of the invention

[0006] The sensing technology based on liquid crystal metamers overcomes the shortcomings of traditional optical sensors. By utilizing the fluidity of liquid crystals, the liquid crystals in the integrated micro-nano optical devices can be replaced with the solution to be tested using a microfluidic control device, without adding a layer of detection cavity in the design, which greatly reduces the cost and provides a new idea for the perception of the solution. The present invention proposes a liquid crystal metamer sensing device based on electromagnetic induced absorption. The liquid crystal metamer is designed based on electromagnetic induced absorption, and the absorption peak is realized by coupling the dark mode and the bright mode; the function of the bright mode is realized by using a single layer of metal, and the function of the dark mode is formed by layered stacking of periodic dielectrics and metals, so that the energy is better localized. At the same time, the peak excited by this liquid crystal metamer has good sensitivity and can be used in sensor research.

[0007] To achieve the above object, the technical solution adopted by the present invention is: The liquid crystal superstructure based on electromagnetic induced absorption to realize refractive index detection is coated with a periodically arranged photonic crystal layer, the medium on both sides of the edge is metallic silver, and the middle is composed of dielectric silicon and E44 liquid crystal arranged alternately. The medium arrangement order of the superstructure structure is Ag 1 -(Si-E44) 5 -Ag 2， The clear mode in the liquid crystal superstructure is Ag 1 The dark mode in the liquid crystal superstructure is (Si-E44)5-Ag 2 .

[0008] In this patent, the metal layer is made of silver, the dielectric layer is made of crystalline silicon, and the detection layer is made of E44 liquid crystal. The periodically arranged structure is composed of dielectric silicon and E44 liquid crystal.

[0009] When electromagnetic waves are incident on this device from air, a sharp absorption peak is formed on the spectrum due to the electromagnetic induced absorption effect. The absorption rate is close to 0 at other frequency positions and close to 1 at the position where electromagnetic induced absorption occurs. The incident electromagnetic wave we are talking about enters the structure from a direction that deviates 30 degrees from the normal. Electromagnetic waves with a frequency of 531.7 terahertz can form a strong absorption peak. The crystalline silicon in the structure is an isotropic dielectric, and its refractive index can be described by the dispersion relation of silicon, and its refractive index is about 3.33.

[0010] Based on the effect of electromagnetic induced absorption, a strong absorption peak can be formed at a specific frequency point, which has good sensing sensitivity and can be used for refractive index detection.

[0011] The liquid crystal in the metamer is E44, and its refractive index for y-polarized incident electromagnetic waves is the refractive index of o-light, and its refractive index value in the frequency band is 1.53.

[0012] As a further improvement of the present invention, the dielectric silicon in the liquid crystal superstructure is an isotropic dielectric, and its refractive index can be described by the dispersion relation of silicon, and its refractive index is about 3.33.

[0013] As a further improvement of the present invention, the thickness of the metal layers on both sides is 60 nm, and the thickness of the silicon and E44 liquid crystal in the middle periodic structure are 200 nm and 90 nm respectively.

[0014] Compared with the prior art, the present invention has the following technical effects: The present invention uses electromagnetic induced absorption to form an absorption peak, replacing the traditional principle of using optical resonant cavity or plasmon effects to form an absorption peak, achieving the effect of having only one absorption peak within the frequency band, so that the refractive index sensor has good recognition.

[0015] In the present invention, the single-layer metal structure is a bright pattern, and the structure formed by alternating arrangement of dielectric and metal is a dark pattern.

[0016] The present invention is effective for y-polarized electromagnetic waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the overall system structure of a liquid crystal metamer for realizing refractive index detection based on electromagnetic induced absorption according to an embodiment of the present invention; Figure 2 A schematic diagram of the body structure of a liquid crystal metamer for realizing refractive index detection based on electromagnetic induced absorption according to an embodiment of the present invention; Figure 3 are the absorption spectra corresponding to structure 1, structure 2 and all structures when the light according to the embodiment of the present invention is incident with y polarization; Figure 4 is a linear fitting curve of the refractive index sensor according to an embodiment of the present invention.

[0018] In the figure, 1 is liquid crystal superstructure; 2 is loading platform; 3 is working platform; 4 is microfluidic control device. DETAILED DESCRIPTION

[0019] The following is a detailed description of the technical solution of the application in conjunction with the accompanying drawings. The described embodiments are only part of the embodiments involved in this patent. All non-innovative embodiments of other researchers in this field based on this embodiment are within the scope of protection of this patent.

[0020] The present invention is a liquid crystal superstructure sensing device based on electromagnetic induced absorption, such as Figure 1The structure 1 is a liquid crystal superstructure 1, the structure 2 is a loading platform 2, which is a load-bearing structure, the structure 3 is a working platform 3, which is a place to complete the operation, and the structure 4 is a microfluidic control device for microfluidic control. In the present invention, the peak of electromagnetic induced absorption is used to realize sensing, mainly for sensing the refractive index of the liquid crystal layer. The specific implementation method is that the liquid crystal of the liquid crystal layer can be poured out and replaced with liquid, involving microfluidic integrated technology, controlling the inlet and outlet channels of the liquid to realize the detection function, and realizing the function of the refractive index sensor.

[0021] When the entire device is working, the liquid to be detected flows from the stage into the metastructure, displacing the liquid crystal therein, and the function of the refractive index sensor is realized by detecting the position of the absorption peak.

[0022] Layered stacking structure 1, such as Figure 2 As shown, the overall medium arrangement order is Ag1-(Si-E44)5-Ag2, where structure 1 is Ag1 which is the bright mode in the liquid crystal superstructure, and structure 2 is (Si-E44)5-Ag2 which is the dark mode in the liquid crystal superstructure. The resonance effect of the two modes induces the electromagnetic induced absorption effect, forming an absorption peak with good performance.

[0023] The middle structure is composed of dielectric silicon and E44, with metallic silver attached to both sides. The refractive index of dielectric silicon is described by the dispersion relation of silicon, and the thickness is 200 nm. The dielectric constant of metallic silver is described by the Drude model, and the thickness is 60 nm. The thickness of E44 liquid crystal is 90 nm, which serves as the cavity to be tested in the detection.

[0024] like Figure 3 As shown, when light is incident with y polarization, the individual structure 1 is a bright mode in the liquid crystal metamer, and the individual structure 2 is a dark mode in the liquid crystal metamer, neither of which will excite an absorption peak. However, when the dark mode is coupled to the bright mode, a strong absorption peak will be excited at a specific frequency position.

[0025] like Figure 4 As shown, when the refractive index sensor is working, it can detect substances with a refractive index of 1.3-1.8, including a variety of important solutions. The linear fit is 0.993 and the sensitivity is 16.7 THz / RIU.

[0026] After a specific design (using electromagnetic induced absorption to form an absorption peak), the present invention can realize the function of a refractive index sensor. The present invention has good sensitivity and linearity, and effectively realizes the function of a sensor.

[0027] The above description is only a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any modification or equivalent change made based on the technical essence of the present invention still falls within the scope of protection required by the present invention.

Claims

1. A liquid crystal metamer for realizing refractive index detection based on electromagnetic induced absorption, characterized in that: The superstructure is coated with a periodically arranged photonic crystal layer, the medium on both sides of the edge is metallic silver, and the middle is composed of dielectric silicon and E44 liquid crystal arranged alternately. The medium arrangement order of the superstructure structure is Ag1-(Si-E44) 5 -Ag 2， The bright mode in the liquid crystal superstructure is Ag1, and the dark mode in the liquid crystal superstructure is (Si-E44)5-Ag2.

2. The liquid crystal metamer for realizing refractive index detection based on electromagnetic induced absorption according to claim 1, characterized in that: The dielectric silicon in the liquid crystal superstructure is an isotropic dielectric, and its refractive index can be described by the dispersion relation of silicon, and its refractive index is about 3.

33.

3. The liquid crystal metamer for realizing refractive index detection based on electromagnetic induced absorption according to claim 1, characterized in that: The thickness of the metal layers on both sides is 60 nm, and the thickness of the silicon and E44 liquid crystal in the periodic structure in the middle are 200 nm and 90 nm respectively.

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