A tunable measurement method and measurement system for metasurface devices

Abstract

The present invention provides a tunable measurement method and measurement system for a metasurface device. The tunable measurement method for a metasurface device comprises: adhering the metasurface device to be measured to a glass sheet to form a micron cavity between the metasurface and the glass sheet; placing the glass sheet and the metasurface device to be measured horizontally; the micron cavity draws in a refractive index-sensitive fluid by capillary action; while a measuring light beam passes through the glass sheet and focuses on the metasurface, it changes the refractive index of the refractive index-sensitive fluid drawn into the micron cavity, and collects the light beam reflected from the metasurface to form a reflection spectrum of the metasurface device to be measured. By changing the dielectric environment above the metasurface, a larger refractive index modulation range can be obtained. Placing the glass sheet and the metasurface device to be measured horizontally improves the uniformity and tuning effect of the metasurface device tuning.

Description

Technical Field

[0001] The present invention relates to the field of metasurface technology, and in particular to a tunable measurement method and measurement system for a metasurface device. Background Art

[0002] Metamaterials are a general term for artificial composite materials fabricated through rigorous subwavelength structural design and processing tailored to specific needs. The emergence of metamaterials offers a new approach to the development of electromagnetic materials. Instead of modifying the material composition, metamaterials can be engineered at a fine-scale to overcome the limitations of natural laws, thereby achieving extraordinary physical properties not found in nature. With the continuous advancement of metamaterials' fundamental theories and structures, functional devices based on metamaterials have flourished, including electromagnetic stealth, perfect lensing, and perfect absorbers.

[0003] The rapid development of modern all-optical communication systems has placed increasingly higher demands on the miniaturization and systematization of optical devices. The emergence of metasurfaces has provided a broader platform for the realization of highly integrated two-dimensional structural optical devices. Metasurfaces are composed of subwavelength-sized structural units, whose thickness is much smaller than the wavelength of light and can be approximated as a two-dimensional plane. By designing their structural parameters point by point, they produce a strong optical response similar to that of nanoantennas, thereby significantly changing the phase of the incident light field and ultimately effectively controlling the output wavefront and wave vector. Currently, the optical response characteristics of most micro-nano optical devices are mainly determined by internal structural parameters, which are difficult to adjust, resulting in poor device performance adjustment capabilities and insufficient adaptability. Summary of the Invention

[0004] The present invention provides a tunable measurement method and measurement system for a metasurface device, which can obtain a larger refractive index modulation range and improve the uniformity and tuning effect of the metasurface device tuning.

[0005] In a first aspect, the present invention provides a tunable measurement method for a metasurface device, which includes: sticking the metasurface device to be measured on a glass sheet to form a micron cavity between the metasurface and the glass sheet; placing the glass sheet and the metasurface device to be measured horizontally; the micron cavity utilizes capillary phenomena to absorb a refractive index-sensitive fluid; while a measuring light beam passes through the glass sheet and is focused on the metasurface, the refractive index of the refractive index-sensitive fluid absorbed into the micron cavity is changed, and the light beam reflected from the metasurface is collected to form a reflection spectrum of the metasurface device to be measured.

[0006] In the above scheme, the metasurface device to be tested is affixed to a glass sheet and, utilizing capillary phenomena, the micrometer-sized cavity between the metasurface and the glass sheet draws in a refractive index-sensitive fluid. During the measurement process, the measuring beam, while passing through the glass sheet and focusing on the metasurface, also changes the refractive index of the refractive index-sensitive fluid drawn into the micrometer-sized cavity. The beam reflected from the metasurface is then collected to form the reflection spectrum of the metasurface device to be tested. In other words, by changing the dielectric environment above the metasurface, a larger refractive index modulation range can be achieved. The reflection spectrum allows observation of the effect of the change in the equivalent refractive index of the dielectric environment above the metasurface device on the perfect absorption effect of the metasurface device to be tested, allowing the physical parameters of the metasurface device to be measured, such as the modulation depth, wavelength modulation range, and response time. Placing the glass sheet and the metasurface device to be tested horizontally minimizes the effect of gravity on the refractive index-sensitive fluid in the micrometer-sized cavity, thereby evenly covering the metasurface and improving the uniformity and tuning effect of the all-optical tuning of the metasurface device.

[0007] In one specific embodiment, the refractive index-sensitive fluid is a refractive index-temperature sensitive liquid. Changing the refractive index of the refractive index-sensitive fluid drawn into the microcavity includes changing the temperature of the refractive index-temperature sensitive liquid drawn into the microcavity to thereby change the refractive index of the refractive index-temperature sensitive liquid drawn into the microcavity. By selecting the refractive index-temperature sensitive liquid as the refractive index-sensitive fluid, the refractive index of the refractive index-temperature sensitive liquid can be changed by changing the temperature of the refractive index-temperature sensitive liquid, thereby simplifying the difficulty of changing the dielectric environment above the metasurface.

[0008] In a specific embodiment, the refractive index-temperature sensitive liquid is toluene, chloroform, ethanol, liquid crystal or magnetic fluid, which facilitates the selection of a suitable refractive index-temperature sensitive liquid.

[0009] In one specific embodiment, changing the temperature of the refractive index-temperature-sensitive liquid drawn into the microcavity to change the refractive index of the refractive index-temperature-sensitive liquid drawn into the microcavity includes emitting a pump beam, which is focused directly or indirectly through a glass sheet into the microcavity between the metasurface and the glass sheet to heat the refractive index-temperature-sensitive liquid drawn into the microcavity, thereby changing the refractive index of the refractive index-temperature-sensitive liquid drawn into the microcavity. By using the pump beam to heat the refractive index-temperature-sensitive liquid drawn into the microcavity, the temperature of the refractive index-temperature-sensitive liquid drawn into the microcavity is changed, thereby changing the dielectric environment above the metasurface, thereby facilitating implementation.

[0010] In one specific embodiment, the refractive index-sensitive fluid is water. Changing the refractive index of the refractive index-sensitive fluid drawn into the microcavity includes changing the temperature of the water drawn into the microcavity, causing the water to transition from a liquid phase to a gas phase, thereby changing the refractive index of the dielectric environment above the metasurface within the microcavity. By utilizing the phase change of water to change the refractive index of the dielectric environment above the metasurface, this process is facilitated while also improving the uniformity and tuning effect of the all-optical tuning of the metasurface device.

[0011] In one specific embodiment, changing the temperature of the water drawn into the microcavity includes emitting a pump beam, which is focused directly or indirectly through a glass sheet into the microcavity between the metasurface and the glass sheet, thereby heating the water drawn into the microcavity, causing the water to transition from a liquid state to a gaseous state, thereby changing the refractive index of the dielectric environment above the metasurface within the microcavity. By using the pump beam to heat the water drawn into the microcavity, the phase transition of the liquid water to a gaseous state occurs, thereby changing the dielectric environment above the metasurface, thereby facilitating the process.

[0012] In one specific embodiment, when the pump beam intensity is below a set threshold, the water within the micron cavity generates nanoscale bubbles from the corners of the metasurface, causing the refractive index tuning range of the dielectric environment above the metasurface to continuously change from one value to another. Specifically, the refractive index tuning range of the dielectric environment above the metasurface can continuously change from 1.333 to 1.0. Alternatively, when the pump beam intensity exceeds a set threshold, the water within the micron cavity gradually converges from nanoscale bubbles at the corners of the metasurface to form micron-scale bubbles, causing the refractive index of the dielectric environment above the metasurface to jump from 1.333 (liquid water) to 1 (gas water). In other words, the refractive index tuning of the dielectric environment above the metasurface is discretely distributed, with a tuning range of discrete changes from 1.333 to 1.

[0013] In one specific embodiment, the refractive index-sensitive fluid is a refractive index-electric field-sensitive liquid. Changing the refractive index of the refractive index-sensitive fluid drawn into the microcavity includes changing the electric field intensity surrounding the refractive index-electric field-sensitive liquid drawn into the microcavity to change the refractive index of the refractive index-electric field-sensitive liquid drawn into the microcavity. By selecting the refractive index-electric field-sensitive liquid as the refractive index-sensitive fluid, the refractive index of the refractive index-electric field-sensitive liquid can be changed by changing the electric field intensity surrounding the refractive index-electric field-sensitive liquid, thereby simplifying the difficulty of changing the dielectric environment above the metasurface.

[0014] In a specific embodiment, the refractive index-electric field sensitive liquid is liquid crystal, which facilitates the selection of a suitable refractive index-electric field sensitive liquid.

[0015] In one specific embodiment, the refractive index-sensitive fluid is a refractive index-magnetic field-sensitive liquid. Changing the refractive index of the refractive index-sensitive fluid drawn into the microcavity includes changing the magnetic field strength surrounding the refractive index-magnetic field-sensitive liquid drawn into the microcavity to change the refractive index of the refractive index-magnetic field-sensitive liquid drawn into the microcavity. By selecting the refractive index-magnetic field-sensitive liquid as the refractive index-sensitive fluid, the refractive index of the refractive index-magnetic field-sensitive liquid can be changed by changing the magnetic field strength surrounding the refractive index-magnetic field-sensitive liquid, thereby simplifying the difficulty of changing the dielectric environment above the metasurface.

[0016] In a specific embodiment, the refractive index-magnetic field sensitive liquid is a magnetic fluid, which facilitates the selection of a suitable refractive index-magnetic field sensitive liquid.

[0017] In a second aspect, the present invention also provides a tunable measurement system for a metasurface device, and the tunable measurement system is based on any one of the above-mentioned tunable measurement methods for a metasurface device. The tunable measurement system for the metasurface device comprises: a sample stage, a measuring beam system, a refractive index changing system, and a reflected beam collecting system. The sample stage has a horizontal support surface, and the sample stage is used to horizontally support the glass sheet and the metasurface device to be measured; the metasurface device to be measured is adhered to the glass sheet to form a micron cavity between the metasurface and the glass sheet; the micron cavity uses capillary phenomena to absorb refractive index sensitive fluid. The measuring beam system is used to emit a measuring beam, and the measuring beam can pass through the glass sheet and focus on the metasurface. The refractive index changing system is used to change the refractive index of the refractive index sensitive fluid absorbed into the micron cavity. The reflected beam collecting system is used to collect the light beam reflected from the metasurface to form a reflection spectrum of the metasurface device to be measured.

[0018] In the above scheme, the metasurface device to be tested is affixed to a glass sheet and, utilizing capillary phenomena, the micrometer-sized cavity between the metasurface and the glass sheet draws in a refractive index-sensitive fluid. During the measurement process, the measuring beam, while passing through the glass sheet and focusing on the metasurface, simultaneously changes the refractive index of the refractive index-sensitive fluid drawn into the micrometer-sized cavity. The beam reflected from the metasurface is then collected to form the reflection spectrum of the metasurface device to be tested. In other words, by changing the dielectric environment above the metasurface, a larger refractive index modulation range can be achieved. The reflection spectrum allows observation of the effect of the change in the equivalent refractive index of the dielectric environment above the metasurface device on the perfect absorption effect of the metasurface device to be tested, allowing the physical parameters of the metasurface device to be measured, such as the modulation depth, wavelength modulation range, and response time. Placing the glass sheet and the metasurface device to be tested horizontally minimizes the effect of gravity on the refractive index-sensitive fluid within the micrometer-sized cavity, thereby evenly covering the metasurface and improving the uniformity and tuning effect of the all-optical tuning of the metasurface device.

[0019] In a specific embodiment, the measurement beam system includes: a supercontinuum light source for emitting a supercontinuum light beam, wherein the supercontinuum light beam is directly or indirectly focused on the metasurface through a glass sheet, and the white light emitted by the supercontinuum light source is focused onto the metasurface as a measurement beam, which can measure the tuning effect of the photothermal effect on the reflectance spectrum of the metasurface sample.

[0020] In one specific embodiment, the measurement beam system further includes an acousto-optic crystal positioned between the supercontinuum light source and the optical path of the metasurface device to be measured. The acousto-optic crystal filters the supercontinuum light beam emitted by the supercontinuum light source to extract a monochromatic beam, which is then focused onto the metasurface as the measurement beam. The addition of the acousto-optic crystal enables measurement of the effect of the metasurface sample's tuning of a monochromatic beam under the photothermal effect.

[0021] In a specific embodiment, the refractive index sensitive fluid is water. The refractive index changing system includes a pump light source, which is used to emit a pump light beam, and the pump light beam can directly or indirectly penetrate the glass sheet and focus on the micron cavity between the metasurface and the glass sheet to heat the water absorbed into the micron cavity, changing the water from liquid to gas, thereby changing the refractive index of the dielectric environment above the metasurface in the micron cavity. By utilizing the phase change of water to change the refractive index of the dielectric environment above the metasurface, it is easy to achieve, while also improving the uniformity and tuning effect of the all-optical tuning of the metasurface device. In addition, by using a pump light beam to heat the water absorbed into the micron cavity, the liquid water is changed into gaseous water, thereby changing the dielectric environment above the metasurface, which is easy to achieve.

[0022] In one specific embodiment, when the intensity of the pump beam emitted by the pump light source is below a set threshold, the water in the micron cavity generates nanoscale bubbles from the corners of the metasurface, causing the refractive index tuning range of the dielectric environment above the metasurface to continuously change from one value to another. Specifically, the refractive index tuning range of the dielectric environment above the metasurface can continuously change from 1.333 to 1.0. Alternatively, when the intensity of the pump beam emitted by the pump light source exceeds a set threshold, the water in the micron cavity gradually converges from nanoscale bubbles at the corners of the metasurface to form micron-scale bubbles, causing the refractive index of the dielectric environment above the metasurface to jump from 1.333 (liquid water) to 1 (gas water). In other words, the refractive index tuning of the dielectric environment above the metasurface is discretely distributed, with a tuning range that varies discretely from 1.333 to 1. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A flow chart of a tunable measurement method for a metasurface device provided in an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of the placement of a metasurface device to be tested and a glass sheet provided in an embodiment of the present invention;

[0025] Figure 3 A horizontal optical path diagram of a tunable measurement system for a metasurface device provided by an embodiment of the present invention;

[0026] Figure 4 for Figure 3 A vertical optical path diagram of a tunable measurement system for a metasurface device is shown;

[0027] Figure 5 A horizontal optical path diagram of a tunable measurement system for another metasurface device provided by an embodiment of the present invention;

[0028] Figure 6 for Figure 5 A vertical optical path diagram of a tunable measurement system for a metasurface device is shown;

[0029] Figure 7 for Figure 5 Another vertical optical path diagram of the tunable measurement system of the metasurface device is shown.

[0030] Reference numerals:

[0031] 11-Metasurface Device 12-Glass Slide 13-Micron Cavity DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0033] To facilitate understanding of the tunable measurement method for metasurface devices provided by an embodiment of the present invention, the following first describes an application scenario of the tunable measurement method provided by an embodiment of the present invention. This tunable measurement method is applied to the all-optical tunable measurement process of a metasurface device. The following describes the tunable measurement method for a metasurface device in detail with reference to the accompanying drawings.

[0034] refer to Figure 1 and Figure 2 The tunable measurement method of a metasurface device provided in an embodiment of the present invention includes:

[0035] Step 10: Glue the metasurface device 11 to be tested onto a glass sheet 12 to form a micron cavity 13 between the metasurface and the glass sheet 12;

[0036] Step 20: Place the glass sheet 12 and the metasurface device 11 to be tested horizontally;

[0037] Step 30: The micro cavity 13 absorbs the refractive index sensitive fluid by using capillary phenomenon;

[0038] Step 40: While the measuring light beam is focused on the metasurface through the glass sheet 12, the refractive index of the refractive index sensitive fluid sucked into the micro cavity 13 is changed, and the light beam reflected from the metasurface is collected to form a reflection spectrum of the metasurface device 11 to be measured.

[0039] In the above scheme, the metasurface device 11 to be tested is affixed to a glass sheet 12, and the capillary phenomenon is utilized to cause the micron cavity 13 between the metasurface and the glass sheet 12 to absorb a refractive index-sensitive fluid. Thus, during the measurement process, while the measuring light beam is focused on the metasurface through the glass sheet 12, it also changes the refractive index of the refractive index-sensitive fluid absorbed into the micron cavity 13, and collects the light beam reflected from the metasurface to form a reflection spectrum of the metasurface device 11 to be tested. In other words, by changing the dielectric environment above the metasurface, a larger refractive index modulation range can be obtained. Through the reflection spectrum, it is possible to observe the effect of the change in the equivalent refractive index of the dielectric environment above the metasurface device 11 to be tested on the perfect absorption effect of the metasurface device 11 to be tested, and measure physical parameters such as the modulation depth, wavelength modulation range, and response time of the metasurface device 11 to be tested. Placing the glass sheet 12 and the metasurface device 11 to be tested horizontally can minimize the degree to which the refractive index-sensitive fluid in the microcavity 13 and the bubbles generated by the photothermal effect are affected by gravity, allowing them to be evenly distributed on the metasurface. This allows the refractive index-sensitive fluid or bubbles in the microcavity 13 to be evenly covered on the metasurface, improving the uniformity and tuning effect of the all-optical tuning of the metasurface device 11. The following describes each of the above steps in detail with reference to the accompanying figures.

[0040] First, refer to Figure 1 and Figure 2 The metasurface device 11 to be tested is adhered to a glass sheet 12 to form a micron cavity 13 between the metasurface and the glass sheet 12. That is, although the metasurface and the surface of the glass sheet 12 are bonded together, a tiny micron cavity 13 structure still exists between the metasurface and the surface of the glass sheet 12.

[0041] Next, if Figure 1 and Figure 2As shown, the glass sheet 12 and the metasurface device 11 to be tested are placed horizontally. In the specific setting, a sample stage can be provided, which has a horizontal support end surface, and the glass sheet 12 and the metasurface device 11 to be tested can be placed on the sample stage in an upper and lower stack. By placing the glass sheet 12 and the metasurface device 11 to be tested horizontally, the degree to which the refractive index sensitive fluid in the micron cavity 13 is affected by gravity can be minimized, so that it is evenly distributed on the metasurface, thereby making the refractive index sensitive fluid or bubbles in the micron cavity 13 evenly covered on the metasurface, thereby improving the uniformity and tuning effect of the all-optical tuning of the metasurface device 11.

[0042] Next, if Figure 1 and Figure 2 As shown, the micron cavity 13 between the glass sheet 12 and the metasurface device 11 to be tested uses the capillary phenomenon to absorb the refractive index sensitive fluid, that is, the refractive index sensitive fluid is filled in the micron cavity 13 between the glass sheet 12 and the metasurface device 11 to be tested. The specific filling method is to use the capillary phenomenon of the micron cavity 13 between the glass sheet 12 and the metasurface device 11 to be tested.

[0043] Next, refer to Figure 1 and Figure 2 While the measuring light beam is focused on the metasurface through the glass sheet 12, it changes the refractive index of the refractive index-sensitive fluid drawn into the microcavity 13, and collects the light beam reflected from the metasurface to form the reflection spectrum of the metasurface device 11 to be tested. That is, by changing the dielectric environment above the metasurface, a larger refractive index modulation range can be achieved. Through the reflection spectrum, it is possible to observe the effect of the change in the equivalent refractive index of the dielectric environment above the metasurface device 11 to be tested on the perfect absorption effect of the metasurface device 11 to be tested, and measure the physical parameters of the metasurface device 11 to be tested, such as the modulation depth, wavelength modulation range, and response time.

[0044] In the above-mentioned step Step 30, when the refractive index sensitive fluid is specifically selected, the refractive index sensitive fluid can be a refractive index-temperature sensitive liquid. At this time, the change of the refractive index of the refractive index sensitive fluid absorbed into the micro cavity 13 in the above-mentioned step Step 40 specifically includes: changing the temperature of the refractive index-temperature sensitive liquid absorbed into the micro cavity 13 to change the refractive index of the refractive index-temperature sensitive liquid absorbed into the micro cavity 13. By selecting the refractive index-temperature sensitive liquid as the refractive index sensitive fluid, the refractive index of the refractive index-temperature sensitive liquid can be changed by changing the temperature of the refractive index-temperature sensitive liquid, thereby simplifying the difficulty of changing the dielectric environment above the metasurface. The above-mentioned refractive index-temperature sensitive liquid can specifically be toluene, chloroform, ethanol, liquid crystal or magnetic fluid, which facilitates the selection of a suitable refractive index-temperature sensitive liquid.

[0045] When specifically changing the temperature of the refractive index-temperature sensitive liquid sucked into the micro cavity 13, refer to Figure 3 and Figure 4 A pump light source can emit a pump beam, which directly or indirectly passes through the glass sheet 12 and is focused on the micro cavity 13 between the metasurface and the glass sheet 12 to heat the refractive index-temperature sensitive liquid absorbed into the micro cavity 13, thereby changing the refractive index of the refractive index-temperature sensitive liquid absorbed into the micro cavity 13. By using the pump beam to heat the refractive index-temperature sensitive liquid absorbed into the micro cavity 13, the temperature of the refractive index-temperature sensitive liquid absorbed into the micro cavity 13 is changed, thereby changing the dielectric environment above the metasurface, which is easy to achieve. Figure 3 and Figure 4 The pump light source may be a 532 nm pump light source, or other types of pump light sources.

[0046] Of course, it should be noted that the refractive index sensitive material is not limited to the above-mentioned method, and other methods can also be used.

[0047] For example, the refractive index sensitive fluid can also be water. At this time, changing the refractive index of the refractive index sensitive fluid sucked into the micro cavity 13 is specifically to change the temperature of the water sucked into the micro cavity 13, and change the water from liquid to gas phase to change the refractive index of the dielectric environment above the metasurface in the micro cavity 13. By using the phase change of water to change the refractive index of water, it is easy to achieve, and at the same time, it also improves the uniformity and tuning effect of the all-optical tuning of the metasurface device. When specifically changing the temperature of the water sucked into the micro cavity 13, it can also be done by means of a pump light source. Reference Figure 3 and Figure 4 , a pump light source can emit a pump beam, which directly or indirectly passes through the glass sheet 12 and is focused on the micron cavity 13 between the metasurface and the glass sheet 12 to heat the water absorbed into the micron cavity 13, changing the water from liquid to gas, thereby changing the refractive index of the dielectric environment above the metasurface in the micron cavity 13. By using a pump beam to heat the water absorbed into the micron cavity 13, the liquid water is changed into gaseous water, thereby changing the dielectric environment above the metasurface, which is easy to achieve. Figure 3 and Figure 4 The pump light source can also be a 532nm pump light source, or other types of pump light sources. Of course, in addition to the above-mentioned method, other methods can also be used to change the temperature of the water sucked into the micro cavity 13.

[0048] In the above-mentioned process of using a pump beam to change the temperature of the water sucked into the micron cavity 13, when the light intensity of the pump beam emitted by the above-mentioned pump light source is lower than the set threshold, the pump light source can first heat the refractive index-temperature sensitive liquid above the corners of the metasurface device 11 to be tested. At this time, the refractive index change effect of the dielectric environment at the corners of the metasurface device 11 to be tested is more obvious. The water in the micron cavity 13 generates nanometer-scale bubbles from the corners of the metasurface, so that the refractive index tuning range of the dielectric environment above the metasurface continuously changes from a certain value to another value. Specifically, the refractive index tuning range of the dielectric environment above the metasurface can continuously change from 1.333 to 1.0.

[0049] Of course, when the intensity of the pump light beam emitted by the above-mentioned pump light source exceeds the set threshold, the pump light source can also first heat the refractive index-temperature sensitive liquid above the corners of the metasurface device 11 to be tested. At this time, the refractive index change effect of the dielectric environment at the corners of the metasurface device 11 to be tested is more obvious. The water in the micron cavity 13 gradually converges from nanometer-scale bubbles at the corners of the metasurface to form micron-scale bubbles, causing the refractive index of the dielectric environment above the metasurface to jump from 1.333 of liquid water to 1 of gaseous water, that is, the refractive index tuning of the dielectric environment above the metasurface is discretely distributed, and its tuning range is discretely changed from a certain value to another value, and its tuning range is discretely changed from 1.333 to 1.

[0050] In another embodiment, the refractive index sensitive fluid may also be a refractive index-electric field sensitive liquid. At this time, the step Step40 of changing the refractive index of the refractive index sensitive fluid absorbed into the microcavity 13 specifically includes: changing the electric field strength around the refractive index-electric field sensitive liquid absorbed into the microcavity 13 to change the refractive index of the refractive index-electric field sensitive liquid absorbed into the microcavity 13. Selecting the refractive index-electric field sensitive liquid as the refractive index sensitive fluid, the refractive index of the refractive index-electric field sensitive liquid can be changed by changing the electric field strength around the refractive index-electric field sensitive liquid, thereby simplifying the difficulty of changing the dielectric environment above the metasurface. The above-mentioned refractive index-electric field sensitive liquid can specifically be liquid crystal, which facilitates the selection of a suitable refractive index-electric field sensitive liquid. When specifically changing the electric field strength of the refractive index-electric field sensitive liquid absorbed into the microcavity 13, refer to Figure 5 and Figure 6 A tunable measurement system for a metasurface device is shown. In this case, no pump light source is required. Two electrodes can be added to the left and right sides of the metasurface device 11 and the glass sheet 12 to be measured to form a capacitor. The capacitor changes the electric field strength around the metasurface device 11 and the glass sheet 12 to be measured, thereby changing the electric field strength of the refractive index-electric field sensitive liquid sucked into the microcavity 13, thereby achieving the purpose of changing the refractive index of the refractive index-electric field sensitive liquid sucked into the microcavity 13.

[0051] In other embodiments, the refractive index sensitive fluid may also be a refractive index-magnetic field sensitive liquid. At this time, the change in the refractive index of the refractive index sensitive fluid absorbed into the microcavity 13 in the above-mentioned step Step 40 specifically includes: changing the magnetic field strength around the refractive index-magnetic field sensitive liquid absorbed into the microcavity 13, so as to change the refractive index of the refractive index-magnetic field sensitive liquid absorbed into the microcavity 13. Selecting the refractive index-magnetic field sensitive liquid as the refractive index sensitive fluid, the refractive index of the refractive index-magnetic field sensitive liquid can be changed by changing the magnetic field strength around the refractive index-magnetic field sensitive liquid, thereby simplifying the difficulty of changing the dielectric environment above the metasurface. The above-mentioned refractive index-magnetic field sensitive liquid is specifically a magnetic fluid, which facilitates the selection of a suitable refractive index-magnetic field sensitive liquid. When specifically changing the magnetic field strength of the refractive index-magnetic field sensitive liquid absorbed into the microcavity 13, refer to Figure 5 and Figure 7 A tunable measurement system for a metasurface device is shown. In this case, no pump light source is required. An energized solenoid coil can be added below the metasurface device 11 and glass sheet 12 to be measured. By controlling the current flowing through the solenoid coil, the magnetic field strength around the metasurface device 11 and glass sheet 12 to be measured is changed, thereby changing the magnetic field strength of the refractive index-electric field sensitive liquid sucked into the microcavity 13, thereby achieving the purpose of changing the refractive index of the refractive index-magnetic field sensitive liquid sucked into the microcavity 13.

[0052] In the various embodiments shown above, the metasurface device 11 to be tested is attached to a glass sheet 12, and the capillary phenomenon is utilized to cause the micron cavity 13 between the metasurface and the glass sheet 12 to absorb a refractive index-sensitive fluid. Thus, during the measurement process, while the measuring light beam is focused on the metasurface through the glass sheet 12, it also changes the refractive index of the refractive index-sensitive fluid absorbed into the micron cavity 13, and collects the light beam reflected from the metasurface to form a reflection spectrum of the metasurface device 11 to be tested. That is, by changing the dielectric environment above the metasurface, a larger refractive index modulation range can be obtained. Through the reflection spectrum, the effect of the change in the equivalent refractive index of the dielectric environment above the metasurface device 11 to be tested on the perfect absorption effect of the metasurface device 11 to be tested can be observed, and physical parameters such as the modulation depth, wavelength modulation range, and response time of the metasurface device 11 to be tested can be measured. Placing the glass sheet 12 and the metasurface device 11 to be tested horizontally can minimize the degree to which the refractive index-sensitive fluid in the microcavity 13 and the bubbles generated by the photothermal effect are affected by gravity, so that they are evenly distributed on the metasurface, thereby making the refractive index-sensitive fluid or bubbles in the microcavity 13 evenly covered on the metasurface, thereby improving the uniformity and tuning effect of the all-optical tuning of the metasurface device 11.

[0053] In addition, an embodiment of the present invention further provides a tunable measurement system for a metasurface device, and the tunable measurement system is based on any one of the above-mentioned tunable measurement methods for a metasurface device. Figure 1 、 Figure 2 、 Figure 3 and Figure 4 The tunable measurement system of the metasurface device includes: a sample stage (not shown in the figure), a measuring beam system, a refractive index changing system, and a reflected beam collecting system. The sample stage has a horizontal supporting surface, which is used to horizontally support the glass sheet 12 and the metasurface device 11 to be measured; the metasurface device 11 to be measured is adhered to the glass sheet 12 to form a micron cavity 13 between the metasurface and the glass sheet 12; the micron cavity 13 uses capillary phenomena to absorb refractive index sensitive fluid. The measuring beam system is used to emit a measuring beam, which can pass through the glass sheet 12 and focus on the metasurface. The refractive index changing system is used to change the refractive index of the refractive index sensitive fluid absorbed into the micron cavity 13. The reflected beam collecting system is used to collect the light beam reflected from the metasurface to form a reflection spectrum of the metasurface device 11 to be measured.

[0054] In the above scheme, the metasurface device 11 to be tested is affixed to a glass sheet 12, and the capillary phenomenon is utilized to cause the micron cavity 13 between the metasurface and the glass sheet 12 to absorb a refractive index-sensitive fluid. Thus, during the measurement process, while the measuring light beam is focused on the metasurface through the glass sheet 12, it also changes the refractive index of the refractive index-sensitive fluid absorbed into the micron cavity 13, and collects the light beam reflected from the metasurface to form a reflection spectrum of the metasurface device 11 to be tested. In other words, by changing the dielectric environment above the metasurface, a larger refractive index modulation range can be obtained. Through the reflection spectrum, it is possible to observe the effect of the change in the equivalent refractive index of the dielectric environment above the metasurface device 11 to be tested on the perfect absorption effect of the metasurface device 11 to be tested, and measure physical parameters such as the modulation depth, wavelength modulation range, and response time of the metasurface device 11 to be tested. Placing the glass sheet 12 and the metasurface device 11 to be tested horizontally can minimize the degree to which the refractive index-sensitive fluid in the microcavity 13 and the bubbles generated by the photothermal effect are affected by gravity, allowing them to be evenly distributed on the metasurface. This allows the refractive index-sensitive fluid or bubbles in the microcavity 13 to be evenly covered on the metasurface, improving the uniformity and tuning effect of the all-optical tuning of the metasurface device 11. The following describes each of the above structures in detail with reference to the accompanying drawings.

[0055] First of all, it needs to be explained that Figures 3 to 6 The xy plane is the optical platform plane, and the xz plane is perpendicular to the optical platform. Figure 3 and Figure 4 1 and 2 show the horizontal optical path portion (top view) and the vertical optical path portion (front view) of the same tunable measurement system. Figure 5 and Figure 6 Figure 1 shows the horizontal optical path portion (top view) and the vertical optical path portion (front view) of the same tunable measurement system. Figure 5 and Figure 7 In combination, the horizontal optical path portion (top view) and the vertical optical path portion (front view) of another tunable measurement system can also be shown.

[0056] When setting up the sample stage, a platform structure with a horizontal support surface can be used as the sample stage. The sample stage is used to horizontally support a glass sheet 12 and a metasurface device 11 to be tested. The metasurface device 11 to be tested is adhered to the glass sheet 12 to form a microcavity 13 between the metasurface and the glass sheet 12. As described in the method section above, the microcavity 13 can absorb a refractive index-sensitive fluid by capillary action. The selection of the refractive index-sensitive fluid is described in the method section above and will not be repeated here.

[0057] When setting up the above-mentioned measuring beam system, if Figure 3 and Figure 5 As shown, the measurement beam system may include a supercontinuum light source for emitting a supercontinuum light beam, wherein the supercontinuum light beam is directly or indirectly focused on the metasurface through the glass sheet 12, and the white light emitted by the supercontinuum light source is focused on the metasurface as the measurement beam, which can measure the tuning effect of the photothermal effect on the reflectance spectrum of the metasurface sample. Specifically, refer to Figure 3 and Figure 4 The supercontinuum light beam emitted by the supercontinuum light source can be focused onto the metasurface device 11 to be tested through multiple mirrors, choppers, semi-transparent and semi-reflective mirrors, and objective lenses.

[0058] Continue to refer Figure 3 and Figure 5 , an acousto-optic crystal can also be added to the measurement beam system. The acousto-optic crystal is located between the supercontinuum light source and the optical path of the metasurface device 11 to be measured. After filtering out a monochromatic beam from the supercontinuum light source, the monochromatic beam is focused on the metasurface as the measurement beam. At this time, the reference Figure 3 and Figure 4 The supercontinuum beam emitted by the supercontinuum light source can first be filtered by an acousto-optic crystal for monochromatic beam filtering, and then focused onto the metasurface device 11 under test through multiple mirrors, a chopper, a semi-transparent and semi-reflective mirror, and an objective lens. By adding an acousto-optic crystal, the tuning effect of the metasurface sample on a monochromatic beam under the action of the photothermal effect can be measured. Of course, if monochromatic beam detection is not performed, there is no need to place an acousto-optic crystal in the measurement beam system.

[0059] The above refractive index changing system is specifically related to the selected refractive index sensitive fluid. For example, when the refractive index sensitive fluid is water, refer to Figure 3 and Figure 4, the refractive index changing system may include a pump light source, which is used to emit a pump light beam, and the pump light beam can directly or indirectly pass through the glass sheet 12 and focus on the micron cavity 13 between the metasurface and the glass sheet 12 to heat the water absorbed into the micron cavity 13, and change the water from liquid to gas, thereby changing the refractive index of the dielectric environment above the metasurface in the micron cavity 13. By utilizing the phase change of water to change the refractive index of water, the dielectric environment above the metasurface is changed, which is easy to achieve, and at the same time, the uniformity and tuning effect of the all-optical tuning of the metasurface device 11 are improved. And by using a pump light beam to heat the water absorbed into the micron cavity 13, the liquid water is changed into gaseous water, thereby changing the dielectric environment above the metasurface, which is easy to achieve. In specific implementation, such as Figure 3 and Figure 4 As shown, the pump beam emitted by the pump light source can pass through the half-reflecting half-mirror and the objective lens and be incident on the micron cavity 13 between the metasurface device 11 to be tested and the glass sheet 12. A power detector can also be added to obtain the parameters of the pump beam in real time through the half-reflecting half-mirror for monitoring and adjustment.

[0060] As described in the aforementioned method section, when the intensity of the pump beam emitted by the pump light source is below a set threshold, the water in the microcavity 13 generates nanometer-scale bubbles from the corners of the metasurface, causing the refractive index tuning range of the dielectric environment above the metasurface to continuously change from a certain value to another value. Specifically, the refractive index tuning range of the dielectric environment above the metasurface can continuously change from 1.333 to 1.0. Similarly, when the intensity of the pump beam emitted by the pump light source exceeds a set threshold, the water in the microcavity 13 gradually converges from nanometer-scale bubbles at the corners of the metasurface to form micrometer-scale bubbles, causing the refractive index of the dielectric environment above the metasurface to jump from 1.333 of liquid water to 1 of gaseous water. In other words, the refractive index tuning of the dielectric environment above the metasurface is discretely distributed, and its tuning range varies discretely from 1.333 to 1. The details are described in the aforementioned method section and will not be repeated here.

[0061] In addition, when the refractive index sensitive fluid is a refractive index-electric field sensitive liquid or a refractive index-magnetic field sensitive liquid, the specific refractive index changing system can refer to Figure 6 or Figure 7 The setting method shown is described in the above method section and will not be repeated here.

[0062] When setting up the above-mentioned reflected beam collection system, if Figure 2 、 Figure 4 、 Figure 6 and Figure 7As shown, the reflected light beam reflected from the metasurface device 11 to be tested passes through the objective lens, half-reflective half-mirror, reflector, half-reflective half-mirror, reflector, filter, half-reflective half-mirror in sequence, and enters the spectrometer for collection, thereby forming the reflection spectrum of the metasurface device 11 to be tested. In addition, as Figure 4 、 Figure 6 and Figure 7 As shown, a CCD camera can also be set to monitor the collected reflected light beam in real time.

[0063] In addition, reference Figure 4 、 Figure 6 and Figure 7 A white light illumination source system may also be added, which includes a white light illumination source and a lens for emitting an illumination source toward the metasurface device 11 to be tested and the glass sheet 12 to find the specific position of the metasurface device 11 to be tested on the glass sheet 12.

[0064] In the various embodiments shown above, the metasurface device 11 to be tested is attached to a glass sheet 12, and the capillary phenomenon is utilized to cause the micron cavity 13 between the metasurface and the glass sheet 12 to absorb a refractive index-sensitive fluid. Thus, during the measurement process, while the measuring light beam is focused on the metasurface through the glass sheet 12, it also changes the refractive index of the refractive index-sensitive fluid absorbed into the micron cavity 13, and collects the light beam reflected from the metasurface to form a reflection spectrum of the metasurface device 11 to be tested. That is, by changing the dielectric environment above the metasurface, a larger refractive index modulation range can be obtained. Through the reflection spectrum, the effect of the change in the equivalent refractive index of the dielectric environment above the metasurface device 11 to be tested on the perfect absorption effect of the metasurface device 11 to be tested can be observed, and physical parameters such as the modulation depth, wavelength modulation range, and response time of the metasurface device 11 to be tested can be measured. Placing the glass sheet 12 and the metasurface device 11 to be tested horizontally can minimize the degree to which the refractive index-sensitive fluid in the microcavity 13 and the bubbles generated by the photothermal effect are affected by gravity, so that they are evenly distributed on the metasurface, thereby making the refractive index-sensitive fluid or bubbles in the microcavity 13 evenly covered on the metasurface, thereby improving the uniformity and tuning effect of the all-optical tuning of the metasurface device 11.

[0065] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A tunable measurement method for a metasurface device, characterized in that: include: gluing a metasurface device to be tested onto a glass sheet to form a microcavity between the metasurface and the glass sheet; Placing the glass sheet and the metasurface device to be tested horizontally; The micro cavity utilizes capillary phenomenon to absorb the refractive index sensitive fluid; The measuring light beam is focused on the metasurface through the glass sheet, while changing the refractive index of the refractive index sensitive fluid sucked into the microcavity, and collecting the light beam reflected from the metasurface to form a reflection spectrum of the metasurface device to be measured; The refractive index sensitive fluid is a refractive index-temperature sensitive liquid; Changing the refractive index of the refractive index-sensitive fluid absorbed into the microcavity includes: emitting a pump light beam, wherein the pump light beam is directly or indirectly transmitted through the glass sheet and focused into the microcavity between the metasurface and the glass sheet to heat the refractive index-temperature sensitive liquid absorbed into the microcavity, thereby changing the refractive index of the refractive index-temperature sensitive liquid absorbed into the microcavity.

2. The tunable measurement method according to claim 1, wherein: The refractive index-temperature sensitive liquid is toluene, chloroform, ethanol, liquid crystal or magnetic fluid.

3. A tunable measurement method for a metasurface device, characterized in that: include: gluing a metasurface device to be tested onto a glass sheet to form a microcavity between the metasurface and the glass sheet; Placing the glass sheet and the metasurface device to be tested horizontally; The micro cavity utilizes capillary phenomenon to absorb the refractive index sensitive fluid; The measuring light beam is focused on the metasurface through the glass sheet, while changing the refractive index of the refractive index sensitive fluid sucked into the microcavity, and collecting the light beam reflected from the metasurface to form a reflection spectrum of the metasurface device to be measured; The refractive index sensitive fluid is water; Changing the refractive index of the refractive index sensitive fluid sucked into the micro cavity comprises: changing the temperature of the water sucked into the micro cavity to change the phase of the water from liquid to gas, thereby changing the refractive index of the dielectric environment above the metasurface in the micro cavity; Changing the temperature of the water sucked into the micro cavity comprises: A pump beam is emitted, and the pump beam is focused directly or indirectly through the glass sheet into the micron cavity between the metasurface and the glass sheet to heat the temperature of the water absorbed into the micron cavity, changing the phase of the water from liquid to gas, thereby changing the refractive index of the dielectric environment above the metasurface in the micron cavity.

4. The tunable measurement method according to claim 3, wherein: The light intensity of the pump beam is lower than a set threshold, and the water in the micron cavity generates nanometer-scale bubbles from the corners of the metasurface; or When the light intensity of the pump beam exceeds a set threshold, the water in the micron cavity gradually converges from nanometer-scale bubbles at the corners of the metasurface to form micron-scale bubbles.

5. A tunable measurement system for a metasurface device, the tunable measurement system being based on the tunable measurement method for a metasurface device according to any one of claims 1 to 4, characterized in that: include: A sample stage having a horizontal support surface, the sample stage being used to horizontally support the glass sheet and the metasurface device to be tested; wherein the metasurface device to be tested is adhered to the glass sheet to form a micron cavity between the metasurface and the glass sheet; the micron cavity utilizes capillary action to absorb a refractive index sensitive fluid; a measuring beam system, configured to emit a measuring beam, wherein the measuring beam can be focused on the metasurface through the glass sheet; a refractive index changing system for changing the refractive index of the refractive index sensitive fluid sucked into the microcavity; a reflected beam collection system, configured to collect the light beam reflected from the metasurface to form a reflection spectrum of the metasurface device to be measured; Wherein, the refractive index sensitive fluid is a refractive index-temperature sensitive liquid; The refractive index changing system includes a pump light source, which is used to emit a pump light beam. The pump light beam is directly or indirectly transmitted through the glass sheet and focused into the micron cavity between the metasurface and the glass sheet to heat the refractive index-temperature sensitive liquid absorbed into the micron cavity, thereby changing the refractive index of the refractive index-temperature sensitive liquid absorbed into the micron cavity.

6. The tunable measurement system according to claim 5, wherein: The measuring beam system comprises: A supercontinuum light source for emitting a supercontinuum light beam, wherein the supercontinuum light beam is focused on the metasurface directly or indirectly through the glass sheet.

7. The tunable measurement system according to claim 6, wherein: The measuring beam system further comprises: An acousto-optic crystal is located between the supercontinuum light source and the optical path of the metasurface device to be measured, and is used to filter out a monochromatic beam from the supercontinuum light source and focus the monochromatic beam as the measurement beam on the metasurface.

8. A tunable measurement system for a metasurface device, the tunable measurement system being based on the tunable measurement method for a metasurface device according to any one of claims 1 to 4, characterized in that: include: A sample stage having a horizontal support surface, the sample stage being used to horizontally support the glass sheet and the metasurface device to be tested; wherein the metasurface device to be tested is adhered to the glass sheet to form a micron cavity between the metasurface and the glass sheet; the micron cavity utilizes capillary action to absorb a refractive index sensitive fluid; a measuring beam system, configured to emit a measuring beam, wherein the measuring beam can be focused on the metasurface through the glass sheet; a refractive index changing system for changing the refractive index of the refractive index sensitive fluid sucked into the microcavity; a reflected beam collection system, configured to collect the light beam reflected from the metasurface to form a reflection spectrum of the metasurface device to be measured; The refractive index sensitive fluid is water; The refractive index changing system comprises: A pump light source is configured to emit a pump light beam, wherein the pump light beam is capable of directly or indirectly penetrating the glass sheet and focusing on the micron cavity between the metasurface and the glass sheet to heat the water drawn into the micron cavity, thereby changing the water from a liquid phase to a gas phase, thereby changing the refractive index of the dielectric environment above the metasurface in the micron cavity.

9. The tunable measurement system according to claim 8, wherein: The light intensity of the pump light beam emitted by the pump light source is lower than a set threshold, and the water in the micron cavity first generates nanometer-scale bubbles from the corners of the metasurface; or, When the light intensity of the pump light beam emitted by the pump light source exceeds a set threshold, the water in the micron cavity gradually converges from nanometer-scale bubbles to micron-scale bubbles.

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