LC-GM-based reconfigurable optical system and reconfigurable method thereof

Abstract

The invention discloses an LC-GM-based reconfigurable optical system, which comprises a graphene metasurface optical unit and an adjustable liquid crystal unit, the graphene metasurface optical unit is matched with the adjustable liquid crystal unit, and the graphene metasurface optical unit and the adjustable liquid crystal unit are structurally integrated; the system further comprises an LC-GM electric control tuning system, and the LC-GM electric control tuning system is used for controlling the graphene metasurface optical unit and the adjustable liquid crystal unit. The invention further provides a reconfigurable method, and the reconfigurable optical system based on the LC-GM and the reconfigurable method solve the problem that switching of multiple optical functions cannot be achieved under the condition that the structure of the optical system is not changed in the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical devices, relates to a reconfigurable optical system based on LC-GM, and also relates to a reconfigurable method of the reconfigurable optical system based on LC-GM. Background Art

[0002] Metasurface is a new type of artificial material with excellent flexible design, customizable properties and adjustability under external stimulation. In the past decade, the research on metasurfaces has begun to develop in various fields, including sensing, modulation, holography, polarization conversion and other fields. Usually, the geometric structure in the metasurface is regulated by changing the fixed unit structure parameters to adjust the optical response, but this static regulation method makes it difficult to produce new functions or characteristics after the device is manufactured, and it cannot be used as flexibly as programmable electronic devices. Graphene has attracted much attention due to its unique electrical and optical properties and adjustability. It can change the carrier concentration by applying bias voltage or chemical doping, thereby artificially modulating its surface conductivity, and realizing passive dynamic modulation of graphene. For example, in 2022, Sambit Kumar Ghosh designed a graphene metasurface cross-polarization converter. Graphene changes its conductivity by moving the Fermi level through electrical control and chemical doping, thereby flexibly adjusting its response to infrared or terahertz spectra. Therefore, by using graphene materials and supplemented by the supersurface resonance unit structure, through bias modulation, precise adjustable selection of optical bands, adjustable filtering, perfect absorption, and perfect reflection functions can be achieved. However, it still has great limitations, mainly that it can only achieve passive modulation, and flexible modulation functions can only be achieved by changing environmental factors. Liquid crystal can achieve active adjustment, and graphene has passive adjustment functions.

[0003] The existing fixed optical system has a single function and cannot achieve switching of multiple optical functions without changing the structure. Therefore, by combining the flowing liquid crystal as the environment and the metasurface unit of the graphene material as the carrier, specific optical functions that can be actively or passively tunable can be achieved. Summary of the invention

[0004] The first purpose of the present invention is to provide a reconfigurable optical system based on LC-GM, which solves the problem in the prior art that it is impossible to switch between multiple optical functions without changing the structure of the optical system.

[0005] A second object of the present invention is to provide an adjustable and reconfigurable method.

[0006] The first technical solution adopted by the present invention is a reconfigurable optical system based on LC-GM, including a graphene metasurface optical unit and an adjustable liquid crystal unit, the graphene metasurface optical unit and the adjustable liquid crystal unit cooperate, and the graphene metasurface optical unit and the adjustable liquid crystal unit are structurally integrated;

[0007] It also includes an LC-GM electrically controlled tuning system, which is used to control the graphene metasurface optical unit and the adjustable liquid crystal unit.

[0008] The graphene supersurface optical unit comprises a first silicon dioxide substrate, a plurality of graphene supersurfaces are evenly arranged on the upper surface of the first silicon dioxide substrate, and an ion gel layer is attached to the surfaces of the plurality of graphene supersurfaces.

[0009] The adjustable liquid crystal unit comprises a second silicon dioxide substrate in a honeycomb shape, the second silicon dioxide substrate is filled with liquid crystal, and a third silicon dioxide substrate is arranged on the upper surface of the second silicon dioxide substrate.

[0010] The second silicon dioxide substrate is located on the upper surface of the graphene supersurface.

[0011] An indium tin oxide layer is disposed between the second silicon dioxide substrate and the third silicon dioxide substrate.

[0012] An indium tin oxide film layer is disposed on the lower surface of the first silicon dioxide substrate.

[0013] The LC-GM electronically controlled tuning system includes a power supply and FPGA.

[0014] The second technical solution adopted by the present invention is a reconfigurable method, which adopts a reconfigurable optical system based on LC-GM, specifically: different optical function drivers are written into FPGA, and the bias voltage of the graphene metasurface is set by FPGA, so as to incident wide-spectrum infrared or terahertz light to complete the tunable and reconfigurable different optical functions.

[0015] The second technical solution of the present invention is also characterized in that:

[0016] The different optical functions are filtering, focusing, beam expansion and multi-target imaging.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The LC-GM-based reconfigurable optical system and its reconfiguration method provided by the present invention can realize different optical functions such as filtering, focusing, and dynamic imaging by changing the logic programming of the optical system without changing the existing system hardware, structure, and space. The present invention is a method for adjustable and reconfigurable optical functions proposed to address the difficulties of the current fixed hardware optical system, which has a single function, poor flexibility, and its adaptability is greatly limited by the hardware's non-adjustable functions. It is a new method for integrating and dynamically adjusting the functions of optical devices such as dynamic imaging, wavefront control, spatial light modulation, biosensing, optical device manufacturing, and medical testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of a reconfigurable optical system based on LC-GM of the present invention;

[0020] Figure 2 It is a schematic diagram of the structure of the graphene supersurface optical unit of the present invention;

[0021] Figure 3 It is a schematic diagram of the structure of the adjustable liquid crystal of the present invention;

[0022] Figure 4 It is a structural schematic diagram of the LC-GM electronically controlled tuning system of the present invention;

[0023] Figure 5 is a schematic flow chart of the reconfigurable method of the present invention;

[0024] Figure 6 It is a schematic diagram of the process of realizing the filtering function of the present invention;

[0025] Figure 7 It is a schematic diagram of the flow chart of realizing the focusing function of the present invention;

[0026] Figure 8 It is a schematic diagram of the process of realizing the beam expansion function of the present invention;

[0027] Fig. 9 It is a schematic diagram of the process of realizing the multi-target imaging function of the present invention.

[0028] In the figure, 1. Graphene metasurface optical unit, 101. first silicon dioxide substrate, 102. graphene metasurface, 103. ion gel layer, 104. indium tin oxide thin film layer; 2. controllable liquid crystal, 201. second silicon dioxide substrate, 202. indium tin oxide layer, 203. third silicon dioxide substrate; 3. LC-GM electrically controlled tuning system. DETAILED DESCRIPTION

[0029] The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments.

[0030] The reconfigurable optical system based on LC-GM provided by the present invention is as follows: Figure 1 As shown, it includes a graphene metasurface optical unit 1, an adjustable liquid crystal unit 2 and an LC-GM (liquid crystal-graphene metasurface) electrically controlled tuning system 3. The graphene metasurface optical unit 1 and the adjustable liquid crystal 2 mainly realize optical functions and phase control of light. The LC-GM electrically controlled tuning system 3 controls the direction or phase of light in the adjustable liquid crystal 2 by driving writing. The LC-GM electrically controlled tuning system 3 controls the Fermi level of the graphene metasurface optical unit 1 by bias writing, thereby realizing resonance, filtering and enhancement of the electromagnetic spectrum.

[0031] like Figure 2As shown, the graphene supersurface optical unit 1 includes a first silicon dioxide substrate 101, and a plurality of graphene supersurfaces 102 are uniformly arranged on the upper surface of the first silicon dioxide substrate 101. The graphene supersurfaces 102 are different shapes realized by etching the graphene film. The optical properties of the graphene supersurfaces 102 with different designs will change differently. Different geometric shapes can be designed according to the needs of the optical functions. The surfaces of the plurality of graphene supersurfaces 102 are all attached with ion gel layers 103 for loading bias voltages, and the main function is to achieve Fermi level regulation of the graphene supersurfaces and to achieve the tuning function of the resonance frequency. An indium tin oxide thin film layer 104 is arranged on the lower surface of the first silicon dioxide substrate 101. Figure 3 As shown, the adjustable liquid crystal unit 2 is mainly used to digitally control the phase of the incident light or electromagnetic wave. The adjustable liquid crystal unit 2 includes a second silicon dioxide substrate 201 in a honeycomb shape. The second silicon dioxide substrate 201 is filled with liquid crystal. A third silicon dioxide substrate 203 is provided on the upper surface of the second silicon dioxide substrate 201. The second silicon dioxide substrate 201 is located on the upper surface of the graphene super surface 102. An indium tin oxide layer 202 is provided between the second silicon dioxide substrate 201 and the third silicon dioxide substrate 203, and the indium tin oxide layer 202 is etched into an electrode array matrix. A control voltage is loaded so that the liquid crystal can accurately control the phase or direction of the incident light; as shown Figure 4 As shown, the LC-GM electrically controlled tuning system 3 includes a power supply and an FPGA. The power supply is mainly used for power supply; the FPGA is mainly used for writing drive, liquid crystal electrode array drive input control and graphene Fermi level bias control. When the optical system function needs to be reconstructed, the electrically controlled tuning system is started. The tuning system can control the liquid crystal electrode array through the preset drive of the FPGA, and can also control the optical function of the graphene metasurface.

[0032] The present invention also provides a reconfigurable method, which adopts the reconfigurable optical system of the above-mentioned LC-GM, specifically: different optical function drivers are written into the FPGA, and the bias voltage of the graphene metasurface 102 is set by using the FPGA, so as to incident wide-spectrum infrared or terahertz light to achieve tunable and reconfigurable different optical functions.

[0033] Among them, the different optical functions are filtering, focusing, beam expansion and multi-target imaging.

[0034] Example 1

[0035] This embodiment provides a reconfigurable optical system based on LC-GM, such as Figure 1-3As shown, it includes a graphene metasurface optical unit 1 and an adjustable liquid crystal unit 2, the graphene metasurface optical unit 1 cooperates with the adjustable liquid crystal unit 2, and the graphene metasurface optical unit 1 and the adjustable liquid crystal unit 2 are structurally integrated; it also includes an LC-GM electrically controlled tuning system 3, and the LC-GM electrically controlled tuning system 3 is used to control the graphene metasurface optical unit 1 and the adjustable liquid crystal unit 2; the graphene metasurface optical unit 1 includes a first silicon dioxide substrate 101, and a plurality of graphene metasurfaces 102 are uniformly arranged on the upper surface of the first silicon dioxide substrate 101, and the surfaces of the plurality of graphene metasurfaces 102 An ion gel layer 103 is attached to each of them; the adjustable liquid crystal unit 2 includes a second silica substrate 201 in a honeycomb shape, the second silica substrate 201 is filled with liquid crystal, and a third silica substrate 203 is provided on the upper surface of the second silica substrate 201; the second silica substrate 201 is located on the upper surface of the graphene supersurface 102; an indium tin oxide thin film layer 104 is provided on the lower surface of the first silica substrate 101; an indium tin oxide layer 202 is provided between the second silica substrate 201 and the third silica substrate 203; the LC-GM electrically controlled tuning system 3 includes a power supply and an FPGA.

[0036] Example 2

[0037] This embodiment provides a reconfigurable method, such as Figure 1-9 As shown, the specific steps are as follows:

[0038] Step 1, setting the parameters of the adjustable and reconfigurable system of liquid crystal graphene optical functions. Based on the results of the optical system function debugging, write the drivers that need to be qualitatively adjusted for filtering and focusing into the FPGA; use the FPGA to set the bias voltage point of the graphene metasurface. The bias voltage is adjustable between 0 and 1 volt, and the adjustment step can be up to 0.01V; the liquid crystal area determines the number of transmission electrodes. Each honeycomb liquid crystal has an indium tin oxide electrode, which is realized by loading different levels of 0-5V to the electrode through the FPGA. Since only the filtering function is realized, there is no need to change the direction of the light path, so all electrodes on the electrode matrix can realize light transmission without adding voltage.

[0039] Step 2, the terahertz light is incident on the third silicon dioxide substrate 203, passes through the third silicon dioxide substrate 203 and the indium tin oxide layer 202 electrode matrix, and is then modulated by high-precision liquid crystal to change the direction or phase of the incident light irradiated to each part of the honeycomb structure to ensure that it can be normally focused to the required position. Then the light passes through the ion gel, which has almost no effect on the light. When the light passes through the graphene metasurface again, it is coupled by the graphene metasurface to achieve resonance, achieve maximum energy and wavelength transmission at the selected wavelength, and almost suppress and transfer energy at the remaining wavelengths, completing the filtering function; finally, the light passes through the silicon dioxide substrate and the indium tin oxide thin film layer without obstacles and is focused on the outside, thereby achieving the optical function of filtering and focusing.

[0040] Example 3

[0041] This embodiment provides a reconfigurable method, such as Figure 1-9 As shown, the specific steps are as follows:

[0042] Step 1, liquid crystal graphene optical function adjustable and reconfigurable system parameter setting, write the beam expansion drive into FPGA through the result of optical system function debugging; use FPGA to set the bias voltage point of graphene metasurface, the bias voltage range is adjustable between 0 and 1 volt, and the adjustment step can be up to 0.01V; through FPGA, different levels of 0-5V are loaded to the electrode to achieve different directions of light at different places on the entire liquid crystal surface, and the control of direction is closely related to the focal length, so before the drive starts, it is necessary to first determine the system focal length value. Since the beam expansion adopts a virtual focus, the calculation method is similar to the focal length. Set the voltage value to a negative value to achieve direction control;

[0043] Step 2, the wide-spectrum infrared is incident on the third silicon dioxide substrate 203, passes through the third silicon dioxide substrate 203 and the indium tin oxide layer 202 electrode matrix, and then is modulated by high-precision liquid crystal to change the direction or phase of the incident light irradiated to each part of the honeycomb structure to ensure that it can be normally expanded to the required position. Then the light passes through the ion gel, which has almost no effect on the light. When the light passes through the graphene metasurface again, it is coupled with the graphene metasurface to achieve resonance, achieve maximum energy and wavelength transmission at the selected wavelength, and almost suppress and transfer energy at other wavelengths to complete the expansion function.

[0044] Example 4

[0045] This embodiment provides a reconfigurable method, such as Figure 1-9 As shown, the specific steps are as follows:

[0046] Step 1, liquid crystal graphene optical function adjustable and reconfigurable system parameter setting, through the results of optical system function debugging, write the multi-target imaging drive into FPGA; use FPGA to set the bias voltage point of the graphene metasurface, the bias voltage range is adjustable between 0 and 1 volt, and the adjustment step can be up to 0.01V; through FPGA to load different levels of 0-5V to the electrode to achieve, in the multi-target imaging drive, due to the imaging requirements of multiple targets on the same plane need to set different focal lengths, resulting in more diversified light direction control, so the control of the light direction is appropriately changed according to the number of targets, taking four targets as an example, four focal length values ​​and four imaging positions are required to focus on the four targets for imaging, so first determine the system's focal length values ​​and imaging position coordinates, establish a coordinate system with the center position of the optoelectronic device at the focusing position as the center, select four focal points that can be imaged, require the four imaging positions to be far apart, to ensure that the imaging at each location will not overlap, so that the four focal length positions can also be determined;

[0047] Step 2, the incident light is incident on the third silicon dioxide substrate 203, passes through the third silicon dioxide substrate 203 and the indium tin oxide layer 202 electrode matrix, and then is modulated by high-precision liquid crystal to change the direction or phase of the incident light irradiated to each part of the honeycomb structure to ensure that the required positions can be imaged normally. Then the light passes through the ion gel, which has almost no effect on the light. When the light passes through the graphene metasurface again, it is coupled with the graphene metasurface to achieve resonance, achieve maximum energy and wavelength transmission at the selected wavelength, and almost suppress and transfer energy at other wavelengths. Finally, the deflection direction of the light is controlled in conjunction with the voltage value of the liquid crystal matrix to complete the multi-target imaging function.

Claims

1. Reconfigurable optical system based on LC-GM, It is characterized in that The invention comprises a graphene supersurface optical unit (1) and an adjustable liquid crystal unit (2), wherein the graphene supersurface optical unit (1) and the adjustable liquid crystal unit (2) cooperate with each other, and the graphene supersurface optical unit (1) and the adjustable liquid crystal unit (2) are structurally integrated; It also comprises an LC-GM electrically controlled tuning system (3), wherein the LC-GM electrically controlled tuning system (3) is used to control the graphene metasurface optical unit (1) and the adjustable liquid crystal unit (2).

2. The reconfigurable optical system based on LC-GM according to claim 1, It is characterized in that The graphene supersurface optical unit (1) comprises a first silicon dioxide substrate (101), a plurality of graphene supersurfaces (102) are evenly arranged on the upper surface of the first silicon dioxide substrate (101), and an ion gel layer (103) is attached to the surface of the plurality of graphene supersurfaces (102).

3. The reconfigurable optical system based on LC-GM according to claim 2, It is characterized in that The adjustable liquid crystal unit (2) comprises a second silicon dioxide substrate (201) in a honeycomb shape, the second silicon dioxide substrate (201) is filled with liquid crystal, and a third silicon dioxide substrate (203) is provided on the upper surface of the second silicon dioxide substrate (201).

4. The reconfigurable optical system based on LC-GM according to claim 3, It is characterized in that The second silicon dioxide substrate (201) is located on the upper surface of the graphene supersurface (102).

5. The reconfigurable optical system based on LC-GM according to claim 3, It is characterized in that An indium tin oxide layer (202) is provided between the second silicon dioxide substrate (201) and the third silicon dioxide substrate (203).

6. The LC-GM based reconfigurable optical system according to claim 2, It is characterized in that An indium tin oxide thin film layer (104) is provided on the lower surface of the first silicon dioxide substrate (101).

7. The reconfigurable optical system based on LC-GM according to claim 2, It is characterized in that The LC-GM electronically controlled tuning system (3) comprises a power supply and an FPGA.

8. A reconfigurable method, using the reconfigurable optical system based on LC-GM as claimed in any one of claims 1 to 7, It is characterized in that Specifically, different optical function drivers are written into the FPGA, and the bias voltage of the graphene metasurface (102) is set using the FPGA, thereby incident wide-spectrum infrared or terahertz light to achieve tunable and reconfigurable different optical functions.

9. The reconfigurable method according to claim 8, It is characterized in that The different optical functions are filtering, focusing, beam expansion and multi-target imaging.

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