Ultrafast heat switching device and design method thereof

Abstract

The invention discloses an ultrafast heat switching device and a design method thereof. The ultrafast heat switch device comprises a first polariton layer, a fixed near-field gap and a second polariton layer which are sequentially arranged from top to bottom. According to the design method, an external ultrafast light pulse is utilized to excite a first polariton layer, and mid-infrared transient polaritons are generated. Time-varying coupling occurs between the transient polaritons and polaritons of the second polariton layer, opening or closing of a near-field thermal radiation channel is dynamically controlled, and a thermal switch function is realized. Based on the synergistic effect of heterostructure terminal pairing and transient polaritons, the picosecond-level response speed and the switch ratio exceeding four orders of magnitude are achieved. Under the optimal design, the device can achieve the laser cooling effect on the emitting electrode in a single switching period, and an innovative solution is provided for nanoscale dynamic thermal management.

Description

Technical Field

[0001] The invention relates to the cross-technical field of micro-nanoscale heat transfer and nanophotonics, and in particular to an ultrafast thermal switch device and a design method thereof. Background Art

[0002] Ultrafast thermal switches can quickly adjust the heat transfer path driven by external stimuli, and have the ability to actively control heat flow within an ultrafast time scale (existing technology can reach nanoseconds). This ability makes it have application prospects in many fields such as on-chip lasers, high-speed optoelectronics, thermo-optical modulation devices and ultrafast thermal imaging. For example, in high-speed optoelectronic integrated chips, integrated ultrafast thermal switches are crucial for quickly dissipating hot spot heat, preventing heat accumulation, minimizing thermal crosstalk and avoiding overheating, which helps to optimize chip integration and performance. Similarly, in on-chip lasers, integrated ultrafast thermal switches will provide precise temperature control, thereby improving the overall performance of the laser and extending its service life.

[0003] The effectiveness of ultrafast thermal switches depends on two key factors: response time and thermal switching ratio (TSR). Ultrafast response time will help to immediately adjust the heat transfer path to prevent thermal damage; while high TSR enables precise control of heat flow, thereby selectively starting efficient cooling or heating processes.

[0004] To this end, a lot of work has been devoted to the development of high-performance ultrafast thermal switching devices. Traditional methods used in solid-state systems mainly rely on designing materials with switchable thermal conductivity, and regulating heat flow by changing their physical or mechanical contact, density, phase state and other factors using external control fields (such as pressure fields, thermal fields, optical fields, electric fields, magnetic fields and stress fields, etc.). For example, in the prior art, designs based on variable phonon thermal conductivity change mass density through pressure fields, and usually show response times ranging from tens of seconds to several minutes (DOI:10.1038 / S41467-021-25083-8); designs regulated by thermal fields usually show response times of seconds (DOI:10.1016 / j.ijheatmasstransfer.2018.12.154); through faster electrical pulses and optimized phonon transmission Recent research progress includes the realization of an ultra-high switching speed of about 1 MHz (microsecond response time) in self-assembled molecular junction thermal switches (DOI:10.1126 / science.abo4297); and the realization of response times of about 150 ns (DOI:10.1126 / science.adj9669) and 15 ns (DOI:10.1038 / s41928-019-0300-8) in antiferroelectric phase change films and superconducting thermal switches, respectively.

[0005] However, further improving the response speed (less than nanoseconds) is challenging due to the slow phonon diffusion process and the slow change of the external control field. In addition, the inherent broad-spectrum nature of phonons in the material leads to a weak dependence of thermal conductivity on the external field, making it difficult to increase the TSR to more than 100 at room temperature.

[0006] Another approach is to achieve a thermal switch based on thermal photon radiation by manipulating the optical dielectric constant of the material surface through an external field. The advantage of this type of thermal switch is that it is based on ultrafast photon transmission and can achieve a faster response time than phonon or electron thermal conduction, especially those designs that operate in the near field. Near-field radiation thermal switches are expected to achieve higher TSR and faster response by utilizing near-field coupled optical modes. However, near-field radiation thermal switches in the prior art are often based on symmetric terminal designs, such as graphene-based heterojunctions or nanostructure resonator schemes. However, in these schemes, once the steady-state polariton coupling between the symmetric terminals is formed, the limited modulation capability of the external field makes it difficult to completely decouple these coupled optical modes, resulting in challenges in quickly closing the thermal channel and limiting their performance (DOI: 10.1021 / acs.nanolett.7b01422; 10.1021 / acsnano.7b08231).

[0007] Therefore, how to realize ultrafast thermal switching devices with faster time response, higher TSR and higher reliability remains a challenge to be solved, which requires the exploration of new materials and mechanisms to form new technical solutions. Summary of the invention

[0008] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide an ultrafast thermal switch device and a design method thereof. The device can achieve a picosecond ultrafast thermal switch device response and a thermal switch ratio of up to four orders of magnitude through the synergistic effect of heterogeneous terminal pairing design and external ultrafast light-excited transient polaritons. Under optimized conditions, the thermal switch device achieves a laser cooling effect on the emitter within a single switching cycle. This innovation provides a new cross-nanoscale interface dynamic thermal control solution for the fields of high-speed optoelectronics, thermo-optical modulators, and on-chip lasers.

[0009] Technical solution overview:

[0010] The ultrafast thermal switch device disclosed in the present invention comprises a first polariton layer, a fixed near-field gap and a second polariton layer arranged in sequence from top to bottom; the first polariton layer is a hot-end emitter, the second polariton layer is a cold-end receiver, and the two are heterogeneous materials; the first polariton layer generates mid-infrared transient polaritons under external ultrafast light excitation, and time-varying coupling occurs with the polaritons of the second polariton layer to realize the thermal switch function. The design concept and principle of the device, such as Fig.10As shown, the design core includes:

[0011] 1) The emitter and the receiver are composed of heterogeneous materials to form an asymmetric parallel plane terminal structure and are separated by a fixed near-field gap. Those skilled in the art can understand that the fixed near-field gap is a vacuum gap, and its vacuum state and gap size should be obtained and maintained using corresponding conditions.

[0012] 2) In the absence of external ultrafast light excitation, due to the heterogeneity of the materials at the two terminals, the spectra of the mid-infrared polaritons do not overlap, and there is no polariton coupling. Therefore, the near-field radiation heat flow between the two terminals is greatly suppressed, and the thermal switch is in the off state.

[0013] 3) When external ultrafast light excites the first polariton layer, a large number of free carriers will be generated, dynamically changing the transient dielectric properties of the material and further generating mid-infrared transient polaritons. These transient polaritons can match the polariton spectrum of the second polariton layer, so they can couple to open the near-field thermal radiation channel and enhance the near-field radiation heat flow. At this time, the thermal switch is in the on state.

[0014] Fig.10 In the equation, n represents the carrier concentration, n0 refers to the initial carrier concentration of the first polariton layer, Δn(Δt) refers to the change of free carriers in the material to Δn after the external ultrafast light excitation, and ∈ refers to the dielectric function of the first polariton layer. In the absence of external ultrafast light excitation, its static dielectric function is ∈ staic ; After the external ultrafast light, the free carriers generated by the excitation will cause the change of its dielectric function. The dielectric function changes to Δ∈(ω,Δt) at the delay time Δt. Therefore, the corresponding transient dielectric constant is ∈(ω,Δt))→∈ staic +Δ∈(ω,Δt).

[0015] 4) When the external ultrafast light excitation ends, the first polariton layer returns to its initial static state, no longer supports mid-infrared polaritons, and there is no polariton coupling between the two terminals, thereby greatly suppressing the near-field radiation heat flow and the thermal switch returns to the closed state.

[0016] 5) As mentioned above, in the ultrafast thermal switch device described in the present invention, the core of the selective pairing of the two-terminal heterogeneous materials is that the polaritons of the two materials have no spectral matching under static conditions; while under the excitation of external ultrafast light, the emitting extreme point (i.e., the first polariton layer) produces mid-infrared transient polaritons, and the transient polaritons have spectral matching with the polaritons in the receiving extreme point (the second polariton layer), so they can couple and open the near-field thermal radiation channel, thereby realizing the thermal switch function.

[0017] 6) By manipulating the excitation conditions of external ultrafast light, such as the laser pulse width and threshold of the ultrafast pump laser, the photoexcited carrier concentration and dynamic process in the first polariton layer can be precisely controlled, thereby controlling the specific operation and performance of the thermal switch. Specifically, the laser threshold controls the photoexcited carrier concentration, thereby determining the maximum radiant heat flux when the thermal switch is turned on; and the laser pulse width determines the carrier lifetime to a certain extent, which in turn affects the time when the thermal switch is turned on, that is, the thermal switch cycle.

[0018] Furthermore, by optimizing the ultrafast pump laser conditions and material parameters, the laser cooling effect of the emitter can be achieved, that is, the energy absorbed by the emitter from the ultrafast pump laser is less than the heat dissipated to the receiver through near-field thermal radiation.

[0019] Preferred technical solution:

[0020] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0021] As a preferred technical solution of the present invention, the first polariton layer includes at least one of transition metal disulfide (TMD material), graphene, black phosphorus, two-dimensional superconducting material, topological insulator material or ferromagnetic material.

[0022] Preferably, the TMD material includes at least one of WS2, MoS2, WSe2 or WTe2; the two-dimensional superconducting material includes NbSe2 and / or FeSe; the topological insulator material includes Bi2Se3; and the ferromagnetic material includes CrI3.

[0023] Preferably, the thickness of the first polariton layer is 0.334 nm to 500 nm.

[0024] As a preferred technical solution of the present invention, the size of the fixed near-field gap is 1 nm to 10 μm.

[0025] As a preferred technical solution of the present invention, the polaritons of the second polariton layer include at least one of plasmon polaritons, phonon polaritons, exciton polaritons or molecular polaritons, and have spectral overlap with the mid-infrared transient polaritons.

[0026] Preferably, the second polariton layer includes at least one of graphene, black phosphorus, boron nitride, molybdenum oxide, silicon oxide, silicon carbide or silicon nitride, and more preferably single-layer graphene.

[0027] Preferably, the thickness of the second polariton layer is 0.334 nm to 500 nm.

[0028] As a preferred technical solution of the present invention, the first polariton layer and the second polariton layer can be any one of a continuous thin film layer, a thin film layer with a nanostructure design, or a heterojunction structure layer.

[0029] As a preferred technical solution of the present invention, a first rigid substrate is provided at one end of the first polariton layer away from the fixed near-field gap.

[0030] Preferably, the first rigid substrate is transparent in the infrared range and does not overlap with the spectrum of the second polariton layer.

[0031] Preferably, the material of the first rigid substrate includes potassium chloride, potassium bromide, and calcium fluoride.

[0032] Preferably, a second rigid substrate is provided at one end of the second polariton layer away from the fixed near-field gap.

[0033] Preferably, the mid-infrared transient polaritons excited by the second rigid substrate and the first polariton layer have spectral overlap.

[0034] Preferably, the material of the second rigid substrate includes silicon dioxide, aluminum nitride, silicon carbide, or aluminum oxide.

[0035] The rigid substrate of the present invention should be set according to the actual situation and needs. It mainly plays a supporting role and has no special effect on the realization of the ultrafast thermal switch device function and the laser cooling effect. When a rigid substrate is set, a first polariton layer with a rigid substrate, such as WSe2 / KCl, and a second polariton layer with a rigid substrate. Such as graphene / SiO2, are all designs that use a heterojunction structure instead of a single thin film layer.

[0036] As a preferred technical solution of the present invention, the external ultrafast light includes an ultrafast pump laser.

[0037] Preferably, the photon energy of the ultrafast pump laser is close to the band gap of the first polariton layer, and can excite the first polariton layer to generate high-density free carriers.

[0038] Preferably, the threshold value (i.e., energy density) of the ultrafast pump laser is 1 μJ·cm -2 ~1J·cm -2 , pulse width is 30fs~1ns, and repetition frequency is 1MHz~5GHz.

[0039] In a second aspect, the present invention provides a design method for the ultrafast thermal switching device described in the first aspect, the design method comprising: designing a first polariton layer, a fixed near-field gap, and a second polariton layer to form the ultrafast thermal switching device; selecting matching external ultrafast light to control the fixed near-field gap and operate it.

[0040] As a preferred technical solution of the present invention, the design method further includes: providing a rigid substrate on the first polariton layer and / or the second polariton layer.

[0041] As a preferred technical solution of the present invention, the design method includes:

[0042] A first polariton layer and a second polariton layer are selected and prepared, wherein the first polariton layer and the second polariton layer are heterogeneous materials; a first rigid substrate is provided at one end of the first polariton layer away from the fixed near-field gap, and a second rigid substrate is provided at one end of the second polariton layer away from the fixed near-field gap; one side of the first polariton layer is used as a hot-end emitter, and one side of the second polariton layer is used as a cold-end receiver, so as to form an ultrafast thermal switching device with asymmetric near-field radiation.

[0043] Initially, the temperature of the hot-end emitter is higher than that of the cold-end receiver, forming a temperature difference between the two terminals, driving the heat flow across the gap between the two terminals; selecting an ultrafast pump laser of a suitable wavelength as the external ultrafast light, and using it to excite the hot-end emitter to generate mid-infrared transient polaritons, and the mid-infrared transient polaritons and the polaritons generated by the cold-end receiver undergo time-varying coupling, so that the ultrafast thermal switch device enters the on state;

[0044] When external ultrafast light excitation is stopped, the short-lived transient polaritons in the first polariton layer decay rapidly, thereby returning the first polariton layer to its initial state, causing the spectra between the two terminals to lose matching, interrupting the time-varying coupling, suppressing the near-field radiation heat flow across the gap, and causing the ultrafast thermal switch device to enter a closed state.

[0045] Preferably, the temperature range of the hot-end emitter is 1K to 2000K, and the temperature range of the cold-end receiver is 0K to 1999K.

[0046] As a preferred technical solution of the present invention, the design method also includes: optimizing the on and off states of the ultrafast thermal switch device by adjusting the parameters of the ultrafast pump laser, realizing laser cooling within the operation cycle, and realizing dynamic adjustment of the ultrafast thermal switch device function and the laser cooling effect.

[0047] Preferably, the parameters of the ultrafast pump laser include at least one of pulse width, threshold, wavelength, power or repetition frequency.

[0048] In a third aspect, the present invention provides a use of the ultrafast thermal switch device described in the first aspect, wherein the uses include laser coolers, on-chip lasers, high-speed optoelectronics, thermo-optical modulators, and ultrafast thermal imaging.

[0049] Compared with the prior art solutions, the present invention has the following significant beneficial effects:

[0050] (1) The present invention adopts an asymmetric heterogeneous terminal structure consisting of a first polariton layer and a second polariton layer separated by a fixed near-field gap. This design can achieve efficient time-varying polariton coupling, thereby realizing the ultrafast thermal switching device function and laser cooling effect, providing a new thermal management mechanism.

[0051] (2) The present invention uses external ultrafast light, such as ultrafast pump laser, to excite high-density hot carriers in the first polariton layer to generate mid-infrared transient polaritons. These transient polaritons and polaritons in the second polariton layer undergo time-varying coupling within a fixed near-field gap, achieving dynamic opening and closing of the near-field thermal radiation channel, providing a new method for precise control of heat flow.

[0052] (3) The present invention realizes an ultrafast thermal switch device response of picoseconds, with a thermal switch ratio of up to 10 4 The above is at least two orders of magnitude higher than the existing thermal switch design. This significant improvement enables the thermal switch of the present invention to quickly and accurately control the heat flow.

[0053] (4) The present invention realizes effective cooling of the thermal emitter. Under optimized conditions, the heat dissipated to the receiving electrode through the near-field radiation channel in a single switching cycle is higher than the energy absorbed from the ultrafast pump laser, thereby introducing a new mechanism of ultrafast laser cooling.

[0054] (5) The present invention controls the intensity, frequency, lifetime, etc. of the mid-infrared transient polaritons coupling by adjusting the parameters of the ultrafast pump laser (such as pulse width, threshold, wavelength, power, and repetition frequency), thereby achieving dynamic adjustment of the thermal switch function and the laser cooling effect. This method improves the controllability and sensitivity of the thermal switch and provides more flexibility for thermal management.

[0055] (6) The present invention provides a new approach and paradigm for precise thermal control in fields such as high-speed optoelectronics, thermo-optical modulators and on-chip lasers, and is expected to promote technological progress and application development in these fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is a schematic diagram of the ultrafast thermal switch device of Example 1 working in Application Example 1.

[0057] Figure 21 is an effective radiation heat conduction diagram of the ultrafast thermal switch device of Example 1 during the opening and closing cycle operation.

[0058] Figure 3 Spectral heat flow distribution diagram of the ultrafast thermal switch device of Example 1 at different delay times after light excitation and in a steady state.

[0059] Figure 4 This is a diagram of the physical mechanism of operation of the ultrafast thermal switch device of Example 1.

[0060] Figure 5 This is a graph showing the variation of the near-field radiation thermal conductivity and thermal switching ratio of the ultrafast thermal switch device of Example 1 in the on / off state with a fixed near-field gap size.

[0061] Figure 6 It corresponds to Figure 5 Ultrafast laser cooling effect driven by thermal switch under 250ps single switching cycle under working conditions (Q c ) with a fixed near-field gap.

[0062] Figure 7a is a comparison diagram of spectral heat flux distribution in the thermal switching state of the ultrafast thermal switching device of Example 2; Figure 7b It is the near-field thermal evanescent photon tunneling cloud diagram corresponding to the on and off states of the thermal switch.

[0063] Figure 8a is a comparison diagram of spectral heat flux distribution in the thermal switching state of the ultrafast thermal switching device of Example 3; Figure 8b It is the near-field thermal evanescent photon tunneling cloud diagram corresponding to the on and off states of the thermal switch.

[0064] Figure 9a is a comparison diagram of spectral heat flux distribution in the thermal switching state of the ultrafast thermal switching device of Example 4; Figure 9b It is the near-field thermal evanescent photon tunneling cloud diagram corresponding to the on and off states of the thermal switch.

[0065] Fig.10 It is a basic principle diagram of the ultrafast thermal switch device described in the present invention. DETAILED DESCRIPTION

[0066] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0067] It should be clear to those skilled in the art that the embodiments are only intended to help understand the present invention and should not be considered as specific limitations of the present invention.

[0068] Existing ultrafast thermal switching device solutions cannot achieve faster response speed (<10ns), higher thermal switching ratio (>100) and higher reliability (no mechanical moving parts, etc.), and it is difficult to meet the needs of active control of heat flow on ultrafast time scales in fields such as high-speed optoelectronics, thermo-optical modulators and on-chip lasers. Considering that the current technical solutions have various limitations and defects, the purpose of the present invention is to provide an asymmetric heterogeneous terminal ultrafast thermal switching device structure design based on fixed near-field gap separation, by using external ultrafast light to excite the mid-infrared transient polaritons of the emitter, and generate time-varying polaritons coupling between the two terminals, thereby realizing the picosecond ultrafast thermal switching device function and laser cooling effect, providing a new solution for precise thermal control across nanoscale interfaces, and proposing a new mechanism for ultrafast laser cooling.

[0069] In some specific embodiments, the present invention provides an ultrafast thermal switching device, comprising a first polariton layer, a fixed near-field gap and a second polariton layer arranged in sequence from top to bottom; the first polariton layer is a hot end emitter, the second polariton layer is a cold end receiver, and the first polariton layer and the second polariton layer are heterogeneous materials; under the excitation of external ultrafast light, the first polariton layer generates mid-infrared transient polaritons, and the mid-infrared transient polaritons and the polaritons of the second polariton layer undergo time-varying coupling.

[0070] The first polariton layer of the present invention has excellent photoelectric response characteristics, and its key feature is that when excited by external ultrafast light of appropriate wavelength, it can generate a high density of free carriers in the thin film layer. Taking WSe2 as an example, this material can produce high-density excitons with a Rydberg energy structure similar to that under the excitation of sub-bandgap near-infrared ultrafast light. These Rydberg excitons contribute persistent spectral features in the mid-infrared range through quantum transitions between their discrete energy levels. Since these transition energies are usually on the order of tens of meV, the transient polariton response is mainly concentrated in the mid-infrared spectral range. These transitions couple with photons to form Rydberg exciton polaritons, thereby producing significant optical responses in the mid-infrared region.

[0071] The key feature of the second polariton layer is that it can achieve good spectral overlap with the mid-infrared transient polaritons excited by light in the first polariton layer. This means that under light excitation conditions, the polaritons between the two terminals can be effectively coupled, thereby opening a near-field radiation heat transfer channel. This coupling is the key to achieving the ultrafast thermal switch device function and laser cooling effect of the present invention.

[0072] In one embodiment, the first polaritonic layer includes at least one of transition metal dichalcogenides (TMD materials), black phosphorus, graphene, two-dimensional superconducting materials, topological insulator materials, or ferromagnetic materials.

[0073] In one embodiment, the TMD material includes MX2, wherein M=Mo and / or W, and X=at least one of S, Se or Te; further, the TMD material includes at least one of WS2, MoS2, WSe2 or WTe2.

[0074] In one embodiment, the two-dimensional superconducting material includes NbSe2 and / or FeSe; the topological insulator material includes Bi2Se3; and the ferromagnetic material includes CrI3.

[0075] In one embodiment, the thickness of the first polariton layer is 0.334nm to 500nm, for example, it can be 0.334nm, 0.5nm, 1nm, 10nm, 25nm, 50nm, 80nm, 100nm, 130nm, 150nm, 180nm, 200nm, 230nm, 250nm, 280nm, 300nm, 320nm, 350nm, 380nm, 430nm, 450nm, 480nm or 500nm, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0076] In one embodiment, the fixed near-field gap is a vacuum gap, and the size of the fixed near-field gap is 1nm to 10μm, for example, it can be 1nm, 3nm, 5nm, 8nm, 10nm, 25nm, 40nm, 50nm, 65nm, 80nm, 90nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0077] Generally speaking, if the size of the gap is too large, the effect of enhancing heat transfer by near-field thermal radiation will disappear, and the thermal switch will fail. If the gap is too small, some quantum effects such as phonon and electron tunneling may occur, resulting in performance deviations. For the selection of a fixed near-field gap size, the principle should be to separate the first polariton layer and the second polariton layer, and to allow the mid-infrared transient polaritons and polaritons generated by the two to couple in the fixed near-field gap. It can be reasonably adjusted according to actual design requirements and needs.

[0078] In one embodiment, the polaritons of the second polariton layer include at least one of plasmon polaritons, phonon polaritons, exciton polaritons, or molecular polaritons, and have spectral overlap with the mid-infrared transient polaritons.

[0079] In one embodiment, the second polariton layer includes at least one of graphene, black phosphorus and a polar dielectric, and the polar dielectric includes at least one of boron nitride, molybdenum oxide, silicon oxide, silicon carbide or silicon nitride; preferably a single-layer or few-layer (1≤number of layers≤10) graphene, and more preferably a single-layer graphene.

[0080] In one embodiment, the thickness of the second polariton layer is 0.334nm to 500nm, for example, it can be 0.334nm, 0.5nm, 1nm, 10nm, 25nm, 50nm, 80nm, 100nm, 130nm, 150nm, 180nm, 200nm, 230nm, 250nm, 280nm, 300nm, 320nm, 350nm, 380nm, 430nm, 450nm, 480nm or 500nm, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are equally applicable.

[0081] It should be noted that the thickness of the first polariton layer and the thickness of the second polariton layer will affect the performance of the polariton mode, such as field strength and loss, and the effects of these two on the polariton mode need to be balanced with each other. Generally, the thinner the thickness, the stronger the field of the polariton confinement, but the corresponding loss is also greater, so there is an optimized thickness range. The selection of specific thickness also needs to depend on the different polariton characteristics brought about by different material selections. Therefore, technicians in this field should aim to achieve mid-infrared transient polaritons and their coupling with polaritons, and reasonably adjust the material selection and thickness of the film according to actual design requirements and needs.

[0082] In one embodiment, the first polariton layer and the second polariton layer are independently modularly designed functional layers, continuous thin film layers, thin film layers with nanostructure designs, or corresponding heterojunction structure layers with different materials and nanostructure designs.

[0083] The core of the design of the present invention is that for the first polariton layer and the second polariton layer separated by a fixed near-field gap, time-varying polariton coupling can occur when appropriate light is excited, thereby opening a near-field radiation heat transfer channel; when light excitation stops and the transient polaritons are completely attenuated, the coupling is cut off and the heat transfer channel is closed. Therefore, as long as the above core functions can be met, there is no restriction on the specific form and structure of the thin film layer, which can be a multi-layer heterojunction thin film layer, or a single layer or multi-layer thin film with periodic patterning, etc., and should be reasonably adjusted according to actual design requirements and needs.

[0084] In one embodiment, since the first polariton layer and the second polariton layer are separated by the fixed near-field gap and serve as two terminals of the near-field radiation thermal switch device, the two terminals can be suspended or a rigid substrate can be selectively added to the bottom of the two terminals to provide necessary support.

[0085] In one embodiment, a first rigid substrate is disposed at one end of the first polariton layer away from the fixed near-field gap.

[0086] In one embodiment, the first rigid substrate is transparent in the infrared range and does not overlap with the spectrum of the second polariton layer.

[0087] In one embodiment, the material of the first rigid substrate includes potassium chloride (KCl), potassium bromide, and calcium fluoride.

[0088] In one embodiment, a second rigid substrate is disposed at one end of the second polariton layer away from the fixed near-field gap.

[0089] In one embodiment, the mid-infrared transient polaritons excited by the second rigid substrate and the first polariton layer have spectral overlap.

[0090] In one embodiment, the material of the second rigid substrate includes silicon dioxide (SiO2), aluminum nitride, silicon carbide, or aluminum oxide.

[0091] The criterion for selecting the rigid substrate of the present invention is to minimize the influence of the substrate on the performance of the thermal switch. Specifically, the substrate integrated with the first polariton layer is preferably transparent in the infrared range and has no spectral overlap with the second polariton layer, thereby effectively suppressing the heat flux when the switch is closed; the substrate integrated with the second polariton layer is preferably a material whose spectrum overlaps with the light-excited mid-infrared transient polaritons of the first polariton layer, which can further enhance the on-state heat flux. For example, KCl is selected as the substrate material of WSe2, and SiO2 is selected as the substrate material of graphene.

[0092] In some specific embodiments, the external ultrafast light comprises an ultrafast pump laser.

[0093] In one embodiment, the photon energy of the ultrafast pump laser is close to the band gap of the first polariton layer, and can excite the first polariton layer to generate high-density free carriers.

[0094] In one embodiment, the threshold value (i.e., energy density) of the ultrafast pump laser is 1 μJ·cm -2 ~1J·cm -2 , pulse width (i.e. duration) is 30fs~1ns, and repetition frequency is 1MHz~5GHz.

[0095] In some specific embodiments, the present invention provides a design method for the ultrafast thermal switch device described in the above embodiments, the design method comprising: designing a first polariton layer, a fixed near-field gap, and a second polariton layer to form the ultrafast thermal switch device; selecting matching external ultrafast light to control the fixed near-field gap and operate it.

[0096] In one embodiment, the design method further includes: providing a rigid substrate on the first polariton layer and / or the second polariton layer.

[0097] In one embodiment, the design method includes:

[0098] Selecting and preparing a first polariton layer and a second polariton layer, wherein the first polariton layer and the second polariton layer are heterogeneous materials; providing a first rigid substrate at one end of the first polariton layer away from the fixed near-field gap, and providing a second rigid substrate at one end of the second polariton layer away from the fixed near-field gap; using one side of the first polariton layer as a hot-end emitter and one side of the second polariton layer as a cold-end receiver, thereby forming an ultrafast thermal switch device with asymmetric near-field radiation;

[0099] Initially, the temperature of the hot-end emitter is higher than the temperature of the cold-end receiver, that is, the first polariton layer is at a relatively high temperature (T h ), while the second polaritonic layer is at a relatively low temperature (T c ), thus forming a certain temperature difference between the two terminals (ΔT = T h -T c , ΔT>0) to drive the heat flow across the gap between the two terminals; select an ultrafast pump laser of a suitable wavelength as the external ultrafast light to excite the hot end emitter to generate mid-infrared transient polaritons. These transient polaritons are time-varyingly coupled with the polaritons generated by the cold end receiver, causing the ultrafast thermal switch device to enter the on state;

[0100] When the external ultrafast light excitation stops, the short-lived transient polaritons in the first polariton layer decay rapidly, returning to their initial state, which results in a spectral mismatch between the two terminals, interrupting the time-varying coupling and suppressing the near-field radiation heat flow across the gap, thereby turning the ultrafast thermal switch device into the off state.

[0101] Preferably, the temperature of the hot end emitter (ie, T h ) is in the range of 1K to 2000K, for example, 1K, 5K, 10K, 50K, 100K, 300K, 500K, 800K, 1000K, 1300K, 1500K, 1800K, 1900K or 2000K, etc. The temperature of the cold end receiving electrode (i.e., T c ) is in the range of 0K to 1999K, such as 0K, 4K, 8K, 25K, 45K, 90K, 200K, 400K, 700K, 900K, 1200K, 1300K, 1600K, 1800K or 1999K, etc.; and the temperature difference ΔT formed between the two terminals is ensured to be equal to (T h -T c )>0.

[0102] It should be noted that the specific temperature selection of the hot end and the cold end should be determined according to the stability of the selected material and the requirements of the application scenario.

[0103] In one embodiment, the design method further includes: optimizing the on and off states of the ultrafast thermal switch device by adjusting the parameters of the ultrafast pump laser, such as at least one of the pulse width, threshold, wavelength, power or repetition frequency, to achieve laser cooling within the operating cycle.

[0104] Specifically, when the thermal emitter terminal, such as WSe2, is excited with sub-bandgap external ultrafast light, a high density of electron-hole pairs, i.e., excitons, are excited in the material during this process. These excitons have discrete energy levels similar to Reed Paul's, and there are mid-infrared quantum transitions between different energy levels. Their strong interaction with photons will form transient Reed Paul exciton polaritons in WSe2. These transient polaritons produce time-varying coupling with polaritons in the second polariton layer, such as surface plasmons in graphene, thereby opening up an energy transfer channel for near-field thermal radiation. This causes the thermal switch to enter the "on" state, promoting heat flow between the two terminals, at which time the heat flux through the fixed near-field gap is maximum (Q on ). When the external ultrafast light excitation is stopped, the photoexcited carriers in WSe2 completely decay and the system returns to its steady-state configuration. In this state, the polariton coupling between the two terminals is cut off, resulting in a minimum heat flux through the fixed near-field gap (Q off), corresponding to the "off" state of the thermal switch. In this way, by controlling the external ultrafast light, the thermal switch function within the ultrafast time scale can be realized. In a single thermal switch operation cycle, the hot end emitter in the thermal switch, i.e., the first polariton layer, is subjected to energy analysis, wherein ultrafast laser absorption is its main energy input mode, and near-field thermal radiation transmission to the cold end receiving pole is the main energy output mode. If the input energy is much smaller than its output energy, the overall thermal switch operation can achieve effective cooling of the thermal emitter.

[0105] It should be emphasized that the key to achieving ultrafast response of thermal switches lies in the simultaneous realization of fast heat transfer mechanisms and high-speed modulation of external ultrafast light. The heat transfer speed within the thermal switch structure itself determines the upper limit potential of the response time, and the specific level of display depends on the modulation speed of the external ultrafast light. For example, if the thermal switch structure itself has a nanosecond response time capability, when it is excited by laser pulses ranging from microseconds to attoseconds, it can only achieve microsecond to nanosecond thermal switch responses. Therefore, if the laser pulse speed of the external ultrafast light is too fast, the main factor affecting the thermal switch response is its own heat transfer mechanism, that is, the excitation, coupling and attenuation of mid-infrared transient polaritons. The device described in the present invention can achieve picosecond response, so the sub-bandgap external ultrafast light can choose a femtosecond pump laser to fully excite the first polariton layer.

[0106] Furthermore, the external ultrafast light of suitable wavelength is preferably of "sub-bandgap" photon energy to meet the excitation conditions and generate a high density of electron-hole pairs (below the Mott threshold), thereby exciting mid-infrared transient polaritons.

[0107] Furthermore, by adjusting the parameters of the sub-bandgap external ultrafast light, such as wavelength, threshold, pulse width, repetition frequency, etc., the intensity, frequency, lifetime, etc. of the transient polariton coupling can be controlled, thereby achieving dynamic adjustment of the thermal switching function and laser cooling effect.

[0108] Exemplarily, in one embodiment, the first polariton layer is a WSe2 layer, and the photon energy of the sub-bandgap external ultrafast light can be taken from a value smaller than the bandgap of the WSe2 layer between 1.51eV and 1.59eV, for example, it can be 1.51eV, 1.52eV, 1.53eV, 1.54eV, 1.55eV, 1.56eV, 1.57eV, 1.58eV or 1.59eV, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0109] Exemplarily, in one embodiment, the threshold of the sub-bandgap external ultrafast light is 1 μJ·cm -2 ~1J·cm -2 , for example, it can be 1 μJ·cm -2, 5μJ·cm -2 , 10μJ·cm -2 , 25μJ·cm -2 , 50μJ·cm -2 、80μJ·cm -2 , 100μJ·cm -2 、300μJ·cm -2 , 500μJ·cm -2 、700μJ·cm -2 , 900μJ·cm -2 、1mJ·cm -2 , 5mJ·cm -2 、10mJ·cm -2 、25mJ·cm -2 、50mJ·cm -2 、80mJ·cm -2 、100mJ·cm -2 、200mJ·cm -2 、400mJ·cm -2 、600mJ·cm -2 、800mJ·cm -2 or 1J·cm -2 The pulse width is 30fs to 1ns, for example, 30fs, 50fs, 80fs, 100fs, 200fs, 300fs, 400fs, 500fs, 600fs, 700fs, 800fs, 900fs, 1ps, 5ps, 8ps, 10ps, 25ps, 50ps, 80ps, 100ps, 200ps, 300ps, 400ps, 500ps, 600ps, 700ps, 800ps, 900ps or 1ns, etc.; the repetition frequency is 1MHz to 5GHz, for example, 1MHz, 5MHz, 8MHz z, 10MHz, 25MHz, 50MHz, 80MHz, 100MHz, 200MHz, 400MHz, 600MHz, 800MHz, 900MHz, 1GHz, 1.3GHz, 1.5GHz, 1.8GHz, 2GHz, 2.3GHz, 2.5GHz, 2.8GHz, 3GHz, 3.2GHz, 3.5GHz, 3.8GHz, 4GHz, 4.3GHz, 4.5GHz, 4.8GHz or 5GHz, but are not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0110] In some specific embodiments, the present invention provides a use of the ultrafast thermal switch device described in the above embodiment, and the uses include laser coolers, on-chip lasers, high-speed optoelectronics, thermo-optical modulators and ultrafast thermal imaging.

[0111] Example 1

[0112] This embodiment provides an ultrafast thermal switch device, including:

[0113] The first polariton layer, the fixed near-field gap and the second polariton layer are arranged in sequence from top to bottom; the first polariton layer is suspended and consists of a WSe2 thin film with a thickness of 300nm; the second polariton layer is arranged opposite to the first polariton layer and consists of a single layer of graphene with a thickness of 0.334nm; by controlling the fixed near-field gap (vacuum gap) to 10nm, the second polariton layer is separated from the first polariton layer to serve as cold and hot terminals respectively.

[0114] Example 2

[0115] This embodiment provides an ultrafast thermal switching device, which has a rigid substrate KCl disposed at one end of the first polariton layer away from the fixed near-field gap, and a rigid substrate SiO2 disposed at one end of the second polariton layer away from the fixed near-field gap. Except for the above, other conditions are exactly the same as those in Embodiment 1.

[0116] Example 3

[0117] This embodiment provides an ultrafast thermal switching device, in which the first polariton layer is replaced by 300nm WSe2, and the second polariton layer is replaced by 100nm thick SiC. Except for the above, other conditions are exactly the same as those in Example 1.

[0118] Example 4

[0119] This embodiment provides an ultrafast thermal switching device, in which the first polariton layer is replaced by 300nm WSe2, and the second polariton layer is replaced by 200nm thick hBN. Except for the above, other conditions are exactly the same as those in Example 1.

[0120] Application Example 1

[0121] This application example provides a design method for an ultrafast thermal switch device, including:

[0122] (1) Designing a first polariton layer, a fixed near-field gap, and a second polariton layer according to various embodiments to form an ultrafast thermal switching device;

[0123] (2) controlling a fixed near-field gap to separate the first polariton layer from the second polariton layer;

[0124] (3) Select a matching femtosecond pump laser as the external ultrafast light and run the operation:

[0125] The first polaritonic layer is placed at a relatively high temperature (T h =400K), as the thermal emitter terminal of near-field radiation; at the same time, the polariton layer is at a relatively low temperature (T c =300K), acting as a receiving terminal, thereby forming a certain temperature difference between the two terminals (ΔT = 100K);

[0126] Ultrafast laser pulses are emitted by femtosecond pump laser, with laser photon energy of about 800nm ​​and laser threshold of 30μJ·cm -2 , the pulse width is 160fs, the thermal emitter terminal is excited, the mid-infrared transient polaritons are generated and coupled with the polaritons generated by the thermal excitation of the receiving terminal, and the ultrafast thermal switch device enters the on state; the femtosecond pump laser is stopped to excite the thermal emitter terminal, the coupling is interrupted, and the ultrafast thermal radiation switch enters the off state. By controlling the on and off states of the ultrafast thermal radiation switch, laser cooling is achieved within the operation cycle.

[0127] Figure 1 FIG. 1 is a schematic diagram of the ultrafast thermal switch device of Example 1 working in Application Example 1, where WSe2 and graphite are integrated into an asymmetric terminal separated by a vacuum fixed near-field gap of 10 nm in size. Specifically, WSe2 is h , while graphene acts as an emitter at a lower temperature T c The lower part acts as a receiving pole, generating ΔT=T between the terminals h -T c temperature difference. When the WSe2 film is irradiated with this ultrafast pump laser, a high density of electron-hole pairs, i.e., excitons, are excited in the material, resulting in a transient change in the optical dielectric constant on the WSe2 film. In WSe2, these hot carriers will produce discrete energy levels similar to Reed Paul's, and there will be quantum transitions between different exciton energy levels (transition energies are on the order of ~10 meV), thereby interacting strongly with photons to produce mid-infrared transient Reed Paul exciton polaritons in WSe2. Subsequently, the transient polaritons thus generated couple with the thermally excited surface plasmons in graphene, and this coupling mediates the time-varying near-field radiation heat transfer characteristics, significantly enhancing the near-field radiation heat flux (Q on ), which causes the thermal switch to enter the "on" state, promoting heat flow between the terminals. Once the femtosecond pump laser stops and the photoexcited electron-hole pairs decay completely, the system returns to its steady-state configuration. In this state, the polariton coupling between the two terminals is cut off, resulting in a minimum heat flux across the gap (Q off ), which corresponds to the "off" state of the thermal switch. Therefore, by controlling the femtosecond pump laser, this design enables thermal switching on an ultrafast time scale.

[0128] Figure 2: This is the effective radiation thermal conductivity diagram of the ultrafast thermal switch device of Example 1 during the opening and closing cycle operation (the repetition frequency of the femtosecond pump laser is about 4 GHz). When ΔT=100K, the response time of the thermal switch is 250 ps.

[0129] Figure 3 is a spectral heat flow distribution diagram of the ultrafast thermal switch device of Example 1 at different delay times and in a steady state after light excitation, and Figure 3 Corresponding to, Figure 4 Schematic diagram of the physical mechanism of operation of the ultrafast thermal switch device of Example 1.

[0130] Figure 5 is a graph showing the variation of the near-field radiation thermal conductivity and thermal switching ratio of the ultrafast thermal switch device of Example 1 in the on / off state with the fixed near-field gap size, Figure 6 The result diagram of the ultrafast laser cooling effect (η>1) driven by thermal switching under a single switching cycle of 500ps corresponding to the conditions of single-layer WSe2 as a function of laser threshold / carrier concentration and temperature difference distribution; Figure 5 Medium G on and G off are the radiation thermal conductances when the thermal switch is turned on and off, respectively, and are calculated according to the following formulas:

[0131]

[0132] Q r is the near-field radiation heat dissipation rate, Q a is the laser energy absorption rate, Q c is the cooling rate of the thermal emitter, which is calculated according to the following formula:

[0133]

[0134] Among them, τ p is the thermal switch switching cycle, α is the light absorption coefficient, P0 is the laser power, A is the incident laser spot area on the emitter surface, and η is the laser cooling effect. Figure 6 In the figure, the black dashed line (η=1) represents Q a Equal to Q r The blue region (η<1) corresponds to the condition where laser cooling occurs, that is, the heat dissipated through the near-field radiation channel is greater than the energy absorbed by the emitter, especially at high temperatures. η<1, that is, Q a r , which means that the energy absorbed by the transmitter from the ultrafast pump laser is less than the heat dissipated to the receiver through the near-field channel, achieving a laser cooling effect.

[0135] Table 1 records the working performance results of the ultrafast thermal switch devices of Examples 1-4 in Application Example 1. ​

[0136] Table 1

[0137] Thermal switch Response time (ps) Thermal switch ratio <![CDATA[Single-switching-cycle average cooling rate (MW·m -2 )]]> Example 1 250 <![CDATA[10 4 ]]> 2.52 Example 2 250 <![CDATA[3.83×10 3 ]]> 2.23 Example 3 250 152 0.28 Example 4 250 83 0.13

[0138] Figure 7a This is a comparison diagram of spectral heat flux distribution in the thermal switching state of the ultrafast thermal switching device of Example 2; Figure 7b The near-field thermal evanescent photon tunneling cloud diagrams corresponding to the on and off states of the thermal switch. Example 2 is a thermal switch configuration supported by a rigid substrate, that is, WSe2 / KCl and graphene / SiO2 are separated by a vacuum gap as cold and hot terminals. The thermal switch response cycle time is still about 250ps, which depends on the pulse width of the ultrafast pump laser and the transient polariton relaxation time. The corresponding thermal switch ratio reaches about 3.83×10 3 .

[0139] Figure 8a This is a comparison diagram of spectral heat flux distribution in the thermal switching state of the ultrafast thermal switching device of Example 3; Figure 8b The cloud diagrams of near-field thermal evanescent photon tunneling correspond to the on and off states of the thermal switch. Example 3 is a design in which 300nm WSe2 and 100nm SiC are separated by a vacuum gap as a cold and hot terminal pairing. The radiative heat flux when turned on (5.59×10 5 W / m 2 ), the radiation heat flux when closed (3.67×10 3 W / m 2 ), corresponding to a thermal switching ratio of about 152, and the switching response time is the same as above, showing a switching period of 250ps.

[0140] Figure 9a This is a comparison diagram of spectral heat flux distribution in the thermal switching state of the ultrafast thermal switching device of Example 4; Figure 9b The cloud diagram of near-field thermal evanescent photon tunneling in the on and off states of the thermal switch. Example 4 is a design of 300nm WSe2 and 200nm hBN separated by a vacuum gap as a cold and hot terminal pairing. The radiation heat flux when turned on (2.70×10 5 W / m 2 ), the radiation heat flux when closed (3.24×10 3 W / m 2 ), corresponding to a thermal switching ratio of about 83, and the switching response time is the same as above, showing a switching period of 250ps.

[0141] From the above, it can be seen that the ultrafast thermal switch device provided by the present invention can achieve a picosecond ultrafast thermal switch device response and a thermal switch ratio of up to four orders of magnitude under optimized configuration. Under a single-layer WSe2 and optimized laser threshold and temperature difference configuration, it can be achieved that the heat radiated from the receiving end through the near-field channel is higher than the energy absorbed by the transmitting end from the ultrafast pump laser, thereby realizing a new mechanism for ultrafast laser cooling, and providing a new solution for precise thermal control across nanoscale interfaces in the fields of high-speed optoelectronics, thermo-optical modulators and on-chip lasers.

[0142] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0143] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0144] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. An ultrafast thermal switch device, characterized in that: The invention comprises a first polariton layer, a fixed near-field gap and a second polariton layer which are sequentially arranged from top to bottom; the first polariton layer is a hot-end emitter, the second polariton layer is a cold-end receiver, and the first polariton layer and the second polariton layer are heterogeneous materials; Under external ultrafast light excitation, the first polariton layer generates mid-infrared transient polaritons, which are time-varyingly coupled with the polaritons of the second polariton layer.

2. The ultrafast thermal switch device according to claim 1, characterized in that: The first polaritonic layer is composed of one or more of the following materials: transition metal disulfide, black phosphorus, graphene, two-dimensional superconducting material, topological insulator material or ferromagnetic material; Preferably, the transition metal disulfide comprises WS2, MoS2, WSe2 or WTe2; the two-dimensional superconducting material comprises NbSe2 and / or FeSe; the topological insulator material comprises Bi2Se3; the ferromagnetic material comprises CrI3; Preferably, the thickness of the first polariton layer is 0.334 nm to 500 nm; Preferably, the size of the fixed near-field gap is 1 nm to 10 μm.

3. The ultrafast thermal switch device according to claim 1, characterized in that: The polaritons of the second polariton layer include at least one of plasmon polaritons, phonon polaritons, exciton polaritons, or molecular polaritons, and have spectral overlap with the mid-infrared transient polaritons; Preferably, the second polariton layer is composed of one or more of the following materials: graphene, black phosphorus, boron nitride, molybdenum oxide, silicon oxide, silicon carbide or silicon nitride; preferably single-layer graphene; Preferably, the thickness of the second polariton layer is 0.334 nm to 500 nm.

4. The ultrafast thermal switch device according to any one of claims 1 to 3, characterized in that: The first polariton layer and the second polariton layer may be any one of a continuous thin film layer, a thin film layer with a nanostructure design, or a heterojunction structure layer.

5. The ultrafast thermal switch device according to any one of claims 1 to 4, characterized in that: A first rigid substrate is disposed at one end of the first polariton layer away from the fixed near-field gap; Preferably, the first rigid substrate is transparent in the infrared range and does not overlap with the spectrum of the polaritons of the second polariton layer; Preferably, the material of the first rigid substrate includes potassium chloride, potassium bromide, and calcium fluoride; Preferably, a second rigid substrate is provided at one end of the second polariton layer away from the fixed near-field gap; Preferably, the second rigid substrate has spectral overlap with the mid-infrared transient polaritons; Preferably, the material of the second rigid substrate includes silicon dioxide, aluminum nitride, silicon carbide, or aluminum oxide.

6. The ultrafast thermal switch device according to any one of claims 1 to 5, characterized in that: The external ultrafast light includes an ultrafast pump laser; Preferably, the photon energy of the ultrafast pump laser is close to the band gap of the first polariton layer, and can excite the first polariton layer to generate high-density free carriers; Preferably, the threshold of the ultrafast pump laser is 1 μJ·cm -2 ~1J·cm -2 , pulse width is 30fs~1ns, and repetition frequency is 1MHz~5GHz.

7. A method for designing an ultrafast thermal switch device according to any one of claims 1 to 6, characterized in that: The design method comprises: Designing the first polariton layer, the fixed near-field gap, and the second polariton layer to form the ultrafast thermal switching device; A matching external ultrafast light is selected to control the fixed near-field gap and operate the work.

8. The design method of the ultrafast thermal switch device according to claim 7, characterized in that: The design method includes: arranging a rigid substrate on the first polariton layer and / or the second polariton layer.

9. The design method of the ultrafast thermal switch device according to claim 7 or 8, characterized in that: The design method comprises: Selecting and preparing a first polariton layer and a second polariton layer to form an ultrafast thermal switching device with asymmetric near-field radiation; Initially, the temperature of the hot-end emitter is higher than that of the cold-end receiver, forming a temperature difference between the two terminals, driving the heat flow across the gap between the two terminals; an ultrafast pump laser of a suitable wavelength is selected as the external ultrafast light to excite the hot-end emitter, generate mid-infrared transient polaritons, and generate time-varying coupling with the polaritons generated by the cold-end receiver, so that the ultrafast thermal switch device enters the on state; Stop external ultrafast light excitation, the short-lived transient polaritons in the first polariton layer decay rapidly, so that the first polariton layer returns to an initial state, the spectrum between the two terminals loses matching, the time-varying coupling is interrupted, the near-field radiation heat flow across the gap is suppressed, and the ultrafast thermal switch device enters a closed state; Preferably, the temperature range of the hot-end emitter is 1K to 2000K, and the temperature range of the cold-end receiver is 0K to 1999K.

10. The design method of the ultrafast thermal switch device according to claim 9, characterized in that: The design method further comprises: By adjusting the parameters of the ultrafast pump laser, the on and off states of the ultrafast thermal switch device are optimized to achieve laser cooling during the operation cycle; Preferably, the parameters of the ultrafast pump laser include at least one of pulse width, threshold, wavelength, power or repetition frequency.

Images