Open Access
Add to BibSonomy
Abstract
In contrast to conventional emitters fashioned from traditional materials, tunable thermal emitters exhibit a distinct propensity to fulfill the demands of diverse scenarios, thereby engendering an array of prospects within the realms of communications, military applications, and control systems. In this paper, a tunable thermal emitter without continuous external excitation is introduced using Ge2Sb2Te5 (GST) and high-temperature-resistant material Mo. It is automatically optimized by inverse design with genetic algorithm (GA) to switch between different functions according to the object temperature to adapt to diverse scenarios. In “off” mode, the emitter orchestrates a blend of infrared (IR) stealth and thermal management. This is evidenced by average absorptivity values of 0.08 for mid-wave infrared (MIR, 3-5 µm), 0.19 for long-wave infrared (LIR, 8-14 µm), and 0.68 for the non-atmospheric window (NAW, 5-8 µm). Conversely, when confronted with high-temperature entities, the emitter seamlessly transitions to “on” mode, instigating a process of radiative cooling. This transformation is reflected in the augmented emissivity of the dual-band atmospheric window including MIR and LIR, attaining peak values of 0.96 and 0.97. This transition yields a cooling potential, quantified at 64 W/m2 at the ambient temperature of 25°C. In addition, our design employs a layered structure, which avoids complex patterned resonators and facilitates large-area fabrication. The emitter in this paper evinces robust insensitivity to polarization variations and the angle of incidence. We believe that this work will contribute to the development in the fields of dynamic tunability for IR stealth, dynamic radiative cooling systems, and thermal imaging.
© 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
1. Introduction
Manipulating the radiative properties of the infrared band is critical in various fields, including infrared camouflage [1,2], radiative cooling [3], energy-efficient windows [4,5], thermophotovoltaic systems [6–8], and personal thermal management [9,10], to name a few. According to the principles outlined by Stefan-Boltzmann's law, any entity existing above absolute zero will inevitably emit thermal energy in the form of electromagnetic (EM) waves, of which the IR band has the most significant thermal effect [11]. Based on this phenomenon, IR thermal imaging technology has been developed and widely used in the military field, and more and more high-precision IR thermal imaging technology has created a formidable challenge to military equipment [12–14]. IR stealth technology and IR imaging technology are two opposites. The key to IR stealth technology is to regulate the IR radiation of the target object to reduce the detectability of the object and the IR radiation of the object is proportional to the emissivity and the fourth power of the temperature. In the atmospheric window, which includes the MIR and the LIR, the atmosphere has high transmission characteristics for IR radiation so IR detection equipment can identify objects relatively easily [15,16]. The operating bands of most IR imaging devices are located in these two atmospheric windows. Therefore, high absorptivity in the dual-band atmospheric window is beneficial for IR imaging technology [17–19]. In contrast, for IR stealth technology, the emissivity of object should be kept as low as possible in the atmospheric window while increasing the emissivity in the NAW to reduce the effects of heat build-up [20–23]. Infrared imaging and stealth function are completely opposite on the emission spectrum. If the device has an ideal spectral switching characteristic at IR bands, it means that it can realize the switching of stealth and detection.
Coincidentally, the peak wavelength of typical blackbody thermal radiation at ambient temperature falls on the LIR, one of the atmospheric windows. Leveraging this salient attribute of atmospheric transmission, an innovative avenue arises wherein the dissipation of heat into the frigid expanse of outer space facilitates the cooling of terrestrial entities [24,25]. Passive radiative cooling is a strategy for achieving cooling without any electrical input, and is immensely attractive for improving energy efficiency. In order to achieve cooling, it needs to reach and maintain a temperature lower than that of the ambient air. Similar to IR imaging, ideal radiative cooling contains a uniform emissivity within wavelength range of 8-14 µm, selectively across the atmospheric window.
Among the inherent properties of natural materials, thermal emissivity exhibits irreversible and unmodifiable characteristics, which limits its application in practice. In the last decades, EM metamaterials have attracted much attention because of their ability to modulate EM waves. Free modulation of radiation using nanomaterials on the subwavelength scale interacting with light matters has become a reality [2,26–28]. EM, and absorbers [29]. However, while the metamaterials are widely used in IR imaging [30,31], radiative cooling [25,32], thermophotovoltaic systems [33], sensing [34]on properties of these studies are impressive, their resonances are non-resettable. Once the structure is fabricated, its spectral properties are subsequently determined and cannot be altered. As the research progressed, more studies showed the possibility of achieving active modulation of metamaterials. Thermally expandable materials have been applied to metamaterials to change the parameters of the unit structure and achieve dynamic tunability [35]. By setting an external voltage to change the carrier transport properties, the metamaterials obtain different spectral correspondences, the disadvantage of this strategy is that the external excitation must be kept sustainable [36]. Researchers have been intrigued by the remarkable properties of phase-change materials, which change their optical properties depending on their morphology. VO2 is a typical phase change material, with its conductivity suppressed at normal room temperature in the insulating state, and exhibiting significant metallic conductivity in the metallic state at temperatures above 68°C [37,38]. However, its response is volatile, like that of electrically tunable materials [39].
Ge2Sb2Te5 is non-volatile which remains in a phase transition state without sustained external excitation, and is widely used in tunable photonic computing, IR thermionics, etc. It is due to the non-volatile properties that it also excels in the field of information storage and preserves messages for a long time. The crystalline state of GST (cGST) has high absorption in the IR region, while the amorphous state of GST (aGST) is transparent [40]. The crystalline ratio of GST can be transformed by heating, laser pulses and applied voltage [41]. Once crystallization or amorphisation is complete, it can remain unchanged at ambient temperature for many years therefore GST is one of the ideal candidates for multifunctional devices [42–44].
In traditional forward design, researchers usually use transmission line theory, coupled mode theory and other theoretical analyses to simplify the solution of Maxwell's system of equations, and the selection of the initial structure is closely linked to the final optimization result [45–47]. It is necessary to introduce inverse design, which is directly related to the characteristics of the target spectrum and is able to continuously and autonomously optimize the structural parameters based on the target spectrum. In the process of functionalization of metamaterials, their intended spectral targets become more and more complex. The general solution is to include more parameters and provide more degrees of freedom by extending a larger design horizon. Unfortunately, complex structures require very precise nanofabrication processes, which increase the difficulty of fabrication. Therefore, it is worthwhile to inverse design the unpatterned multilayers to achieve multifunctional devices with individual and adjustable “on” and “off” states.
In this study, we demonstrate a functionally switchable multilayer membrane device based on an inverse design by controlling the crystallization ratio of GST to achieve the on-off state transition for switching between IR stealth, IR imaging, and passive radiation cooling functions. GA is applied to maximize the absorptivity difference of the dual-band atmospheric window and the NAW to obtain good switching characteristics. Compared with static IR emitters, the design in this paper overcomes the difficulties of non-adjustability, single function, and preparation.
2. Model and method
2.1 Target spectra and structure
According to Kirchhoff's theorem, objects in thermal equilibrium have comparable emissivity and absorptivity [48]. The ideal spectrum of the designed multifunctional device is shown in Fig. 1, including a realistic atmospheric transmittance model [49] shown as a blue-shaded region of 3-14 µm. The selective emitters within the NAW are effective in meeting the requirement for low emissivity at MIR and LIR, being able to camouflage an object as another one radiating temperature at a much lower, thus hiding it in the background environment. Its ideal spectrum requires a unit absorptivity in the NAW bands and zero in the dual-band atmospheric window. Conversely, high absorptivity in the atmospheric window is a requirement for IR detection imaging/radiation cooling. To ensure perfect switching the two ideal spectra should complement each other. Compared to the IR stealth with high emissivity thermal management, it needs low emissivity in the NAW band. In this work, we use Mo and GST alternately stacked to form a six-layer membrane system, with the whole structure at the subwavelength cell size, as shown in the schematic diagram in Fig. 2. Among them, the bottom layer is Mo acting as a reflector, with a thickness thicker than the skin depth, to block the transmission of EM waves. Since the multilayer membrane extends infinitely in the x-axis direction and y-axis direction with perfect periodicity and symmetry, only the longitudinal structural depth of the xz cross-section needs to be considered in the simulation, which is considered a two-dimensional model.
Fig. 1. Atmospheric transmittance (shades of blue) in the IR band (3−14µm) and ideal spectra (black line) for different state of GST.
2.2 Inverse design
Optimization algorithms such as direct binary search algorithms, neural networks, topology optimization, and GA have been applied to design optical metamaterials. GA is a stochastic search optimizer based on the concepts of evolution and natural selection and is essentially a parallel algorithm that has a greater advantage in dealing with multi-objective optimization and discrete domain problems. We use GA for the inverse design of multilayer film systems, which includes the ideal spectrum of Fig. 1, and the design details of the GA are shown in Fig. 3. The setup of initial population is that a metal layer is from 1 to 80 nm thick, and the GST is from 50 to 700 nm thick. Individual of GA is defined by six binary numbers. The thickness information of each layer constitutes a gene fragment of individuals. Here, we define the fitness function (FOM) inspired by previous work [1,2,8]:
Here, due to the consistency between FOM and ideal spectral features, FOM is adopted as the evaluation criterion for stealth and imaging function switching in IR band. $I{R_{eff}}$ represents the IR stealth performance, which involves the reflectance of MIR, LIR and the absorbance of NAW, represented by RMIR, RLIR and ANAW respectively. $\triangle ({I{R_{eff}}} )$ represents the difference in performance between amorphous and crystalline states of GST, including the difference of reflectance of MIR, LIR, and the difference of absorptance of NAW, represented by $\varDelta {R_{MIR}}({a,c} )$, $\varDelta {R_{LIR}}({a,c} )$, and $\varDelta {A_{NAW}}({a,c} )$ respectively. Superior switching characteristics and desirable IR stealth spectral properties become a reality requiring $I{R_{eff}}$ and $\triangle ({IR} )$ infinitely close to 1. In other words, the closer the FOM value is to 1, the better the performance of the multifunctional device. The number of populations of GA is set to 300, the hybridization rate is 70%, the mutation rate is 10%, and the number of iterations is 20 generations. Our implementation of GA went through the construction of the initial population, the calculation of FOM, the selection, hybridization and the mutation operation. The initial population of 300 individuals was constructed within the range above mentioned, and FOM was calculated for each individual and sorted from high to low. The next generation population is generated by the selection, hybridization and mutation operations, and so on until the end of the iteration. Note that the hybridization and mutation operations exclude the best individuals in each generation in order that the best individual is not eliminated.
2.3 Material characteristics
Figure 4(a) plots the dielectric constant of GST in the crystalline and amorphous state [50,51]. The analysis reveals that the imaginary component of aGST closely approximates zero, signifying minimal loss in the IR range and rendering it effectively transparent to IR radiation. Conversely, cGST exhibits a substantial elevation in its optical constants, resulting in its transformation into a proficient IR-absorbing material. At an annealing temperature of about 160 °C, GST can be transformed from the amorphous to the crystalline state, and then back to the amorphous state by a rapid cooling down when the temperature rises to 600 °C [52,53]. Interestingly, GST materials can be made to be in an intermediate state between the crystalline and amorphous states by controlling the annealing temperature, laser irradiation, etc. The Lorentz-Lorenz relation is used to approximate the effective permittivity of the GST phase state [51,54,55].
Fig. 4. (a) Dielectric permittivity dispersion of crystalline and amorphous GST. (b) Dielectric permittivity dispersion of Mo.
3. Results and discussion
3.1 Simulation result and physical mechanism
Finite difference time domain (FDTD) is an approximate method for solving Maxwell's system of equations for numerical simulations, and the commercial software of Lumerical FDTD Solutions is employed. In our simulation, a plane wave propagates into the structure along the z-direction. x-direction boundary condition is a periodic layer. z-direction upper and lower boundary conditions are perfectly matched layers (PMLs), and the unit cell size is set to 0.4µm. The monitor is used to obtain the reflectivity $R(\lambda )$ at a wavelength of $\lambda $. Due to the metal layer at the bottom, the presence of transmittance can be neglected and the absorptivity at the corresponding wavelength $\lambda $ is obtained using $A(\lambda )= 1 - R(\lambda )$. For the Mo/GST/Mo/GST/Mo/GST/Mo/GST six-layer film presented in this paper, the thickness of each layer optimized by GA is 40/394/28/573/15/362 nm, and the results are shown in Fig. 5. When GST is in the amorphous state, the absorptivity is well suppressed in the MIR and LIR bands, with average absorptivity of 0.08 and 0.19 respectively. The absorptivity peak is 0.98 occurring at 5.25 µm and another peak is 0.79 at 6.8 µm. The rather low emissivity level of the object in the IR band makes it difficult to work for IR detection systems, which implies that the likelihood of being detected is greatly reduced. Meanwhile, it has a high average absorptivity of 0.68 in the NAW band, providing a good radiative cooling effect, which helps to dissipate the accumulated energy and thus reduce the temperature, further improving the IR stealth effect. When the GST is modulated to the crystalline state, the function is converted to IR imaging and nighttime passive radiative cooling. This is because the multifunctional device at this time provides high absorptivity in the MIR and LIR bands and the largest possible difference in absorptivity within the NAW. The average absorptivity within the MIR and LIR are 0.37 and 0.71, with peak absorptivity of 0.96 and 0.97 at 3.35 µm and 10.5 µm, respectively. The difference between the peak absorptivity in the MIR, NAW and LIR bands is 0.9, 0.85 and 0.77 for the two different states, respectively, a huge difference that is exactly what is desired for excellent switching characteristics.
A planar cavity consisting of a dielectric film deposited on a metal mirror can resonate to absorb a specific range of wavelengths and reflect the remaining wavelengths [57]. The resonant wavelength depends on the optical thickness of the film, and the phase shift is determined by the interference of the reflected wave with the incident wave inside the cavity. The specific analyses is found in Supplement 1. The incident light acting on the film interferes with the multiple reflected light and enhances the absorption, and more of the light field energy is confined within the film cavity [58]. To explain the physical mechanism of the absorption phenomenon in this work, we provide the electric field distribution diagrams of the multifunctional device at three absorption peaks. When the GST is amorphous, the EM field distribution at the peak is shown in Fig. 6(a)(b). Due to the low extinction coefficient of aGST in the IR band, the incident EM wave has a chance to enter into the Fabry–Pérot cavity (F-P). The 2nd and 3rd metal layers have opposite potential shift vectors, similar to a capacitor, and a strong electric field appears in the cavity. It is also clear from the magnetic field distribution that the incident and reflected EM waves interfere. The role of the F-P cavity is the main reason for the strong absorption at 5.25 µm. When the GST is transformed into the crystalline state, a significant difference is exhibited, as demonstrated in Fig. 6(c)(d). Due to the change in the dielectric constant of cGST, which leads to the gradual decay of the EM wave energy, most of the electric field is concentrated in the topmost layer of cGST. A small amount of EM wave can reach the next layer of GST, and the energy is mainly consumed in the topmost metal. The specific analyses is in Supplement 1.
Fig. 6. Electric and magnetic field distribution in the indicated zx cross sections. (a) Electric field at 5.25 µm. (b) Magnetic field at 5.25 µm. (c) Electric field at 10.5 µm. (d) Magnetic field at 10.5 µm.
3.2 IR stealth and thermal management with aGST
Many objects in nature have a radiation spectrum similar to that of a blackbody, so the radiant temperature of an object can be obtained by detecting the radiant power in the IR band with an IR camera [59–61]:
here, ${T_r}$ is the temperature obtained from the inverse function of the blackbody radiation spectrum. P is the radiant power detected by the IR camera. ${\alpha _{IR}}$ is the emissivity of the IR camera in the operating band (8-14µm), usually ${\alpha _{IR}} = 1$. The detection power of IR imaging is generally made up of the emitted power of the object ${P_{rad}}$ and the reflected power of the ambient radiation ${P_{ref}}$.We consider the size of the unit area and an ambient temperature of 25°C. Based on the emissivity spectra, the detected power in the operating wavelength range of the IR camera is plotted, including the radiated power and the reflected power from the ambient radiation. It can be observed from Fig. 7(a) that although the object's radiation is increasing with temperature, it is significantly lower than the blackbody radiation flux at any given temperature. Below the ambient temperature of 25°C, the detected power is higher than the blackbody radiated power due to the compensation of the ambient radiation. Figure 7(b) reveals the curve of the relationship between the surface temperature of the object and the radiation temperature. When the temperature is 160°C, the detected radiated power of the object is 276.5 W/m2, which is about 37% of that of a blackbody, and this corresponds to the radiation of a blackbody at 61°C. It means that at a temperature of 160°C, the object can masquerade as another object with a temperature of 61°C. In addition, we provide the radiative heat flux curve of the metamaterial at 433 k as shown in Fig. 7(c). With the blackbody as the reference object, the metamaterial we propose has obvious selective emission within 5-8µm.
Fig. 7. (a) The integrated power of the design (solid orange line), self-radiation Prad (dotted yellow line), environmental reflection Pref (dotted green line) and blackbody ((blue line). (b) The relation be-tween detected and real temperature. (c) The spectral radiation intensity of the blackbody (blue line), the design (orange line) at 433 K.
3.3 IR thermal imaging and radiation cooling with cGST
When GST is modulated to the crystalline state, the function is converted to IR imaging detection and nighttime radiative cooling. As can be seen from Fig. 5, its peak absorptivity of 0.96 and 0.97 exist in MIR and LIR, respectively. By controlling the crystalline fraction of GST, the peak absorptivity can be tuned to different wavelengths without changing the structure, which provides options for thermal imaging configurations in aerospace and military fields. Figure 8 shows the absorption spectral characteristics for different crystallization fractions. According to Eq. (4) we can get the dielectric constant of GST under different crystalline fractions. For example, when the crystalline fraction is 75%, the selective emission spectrum is blue-shifted and the absorption peak appears at 8.85 µm with a near-perfect absorptivity. At the same time, the absorptivity within the MIR tends to increase, which is favorable for IR imaging applications [62]. The 25% crystal fraction reduction achieves a tunable absorption of 1.65 µm within the LIR band, including the selective emission of the MIR. This has potential applications in IR color encryption and adaptive thermal management [63]:
The cooling performance of a multifunctional device when used as a radiator is related to the atmospheric radiation, the non-radiative heat gain of the surrounding medium (thermal conduction and thermal convection), and the incident solar radiation. Taking all heat transfer processes into account, the net cooling power (per unit area) of a radiant cooler is defined by Eq. (7) [25,64].
Here, ${P_a}$ is the amount of the incident atmospheric radiation that is absorbed by the radiator. The atmosphere emissivity is given by ${\alpha _a} = 1 - t{(\lambda )^{1/cos\theta }}$, where $t(\lambda )$ is the atmosphere transmittance in the zenith direction. An effective transmittance plateau of between 8-14 µm. ${P_{nonrad}}$ is the nonradiative heat gain of the radiator with the surrounding media, and $q = {q_{cond}} + {q_{conv}}$ is the combined nonradiative heat coefficient from conductive and convective heat exchange of the radiator with the surrounding air. The non-radiant heat gain coefficient can take values from 2 to 6 W/m2/°C [25,65]. The last term on the right-hand side of Eq. (7) expresses the absorbed solar power by the radiator, which is related to radiative cooling in the daytime. Here, we mainly focus on night radiation cooling performance, so we don't take solar radiation into account.
Two metrics can indicate radiative cooling [66]. The first is ${P_{net}}$, the cooling power. Only when the radiative output power exceeds the net absorbed power can the radiator provide actual cooling, that is, ${P_{net}} > 0$. The second is the cooling steady state temperature ${T_s}$. ${P_{net}}$ is positive at ambient temperatures, and the radiator temperature ${T_r}$ decreases to the steady-state temperature ${T_s}$, at which point ${P_{net}}({{T_s}} )= 0$. The cooling power with and without nonradiative heat gain is given in Fig. 9. At ambient temperature, the radiator without nonradiative heat gain has a cooling power of 64 w/m2, which indicates that cooling is still possible at ambient temperature. When the net cooling power is 0, the temperature difference between the radiator and the ambient temperature is 46°C, which means that the radiator can achieve a very low steady-state temperature. In the range of temperatures above ambient, the cooling power increases due to the positive role of heat conduction and convection. As the temperature decreases, the cooling power decreases to 0, and the temperature difference with the ambient temperature is 18 °C. The above two indicators show that the radiator proposed in this paper can achieve a good night cooling effect, which is of unusual significance for reducing energy consumption.
Fig. 9. The cooling of ideal radiator (black) and our radiator(yellow). The inset shows the emission spectrum of an ideal radiator. The solid curves represent the cooling with the exclusion of any solar and nonradiative contributions. The dashed curves include a practical nonradiative heat gain coefficient of 2 W /m2 /°C.
3.4 Performance comparison
According to Kirchhoff’s law, the emissivity of an object at a certain temperature and wavelength is equal to the absorptivity under thermal equilibrium conditions [67]. When we discuss device performance, we consider the absorptivity and emissivity to be equal. To compare the performance of multifunctional devices, we defined the IR stealth performance as ${A_{NAW}} - {A_{MIR}} - {A_{LIR}}$, and the imaging/cooling performance as $({{A_{MIR}} + {A_{LIR}} - {A_{NAW}}} )/2$ based on the target spectrum. Ideally, both reach unity. The absorptivity differences between crystalline and amorphous states of GST within the MIR, NAW, and LIR bands are normalized and used to characterize the modulation depth by $\overline {\varDelta {A_{MIR}}({a,c} )} + \overline {\varDelta {A_{NIR}}({a,c} )} + \overline {\varDelta {A_{LIR}}({a,c} )} $. The comparison results are shown in Table 1. A selective infrared stealth emitter based on Ag/Ge multilayers was demonstrated in Ref. [68] by utilizing an ultrathin metal film and impedance matching to tune the infrared radiation characteristics. In Ref [29], a dual-band absorber based on the composite cross structure was proposed with nearly perfect absorption peaks in both MWIR and LWIR bands. Unfortunately, they have superior performance but cannot be compatible at the same time and do not have tunable properties. Reference [69] investigated an intelligent thermally controlled radiation emitter based on VO2 to realize the switching from high-temperature heat dissipation to low-temperature insulation. Reference [70] investigated the switching between infrared stealth and non-stealth states based on GST. These works possess tunable characteristics, but the performance is not good enough when used as stealth and imaging and cooling functional devices respectively. Compared with previous work, our design realizes IR camouflage with thermal management when GST is in the crystalline state. GST in the amorphous state can be used as an IR imaging detector or a radiation cooling device, which takes into account good switching characteristics (modulation depth 0.34). While Ref. [2] has comparable performance in our work, the complex top grating structure increases the difficulty of large-area preparation and limits the usage scenarios.
Table 1. Performance Comparison of Multifunctional Devices
3.5 Discussion of polarization and incident angle sensitivity
Finally, we discussed the polarization and angle sensitivity of the proposed multifunction device. As shown in Fig. 10(a)(b), the multifunctional devices have polarization- independent properties when the GST is both crystalline and amorphous. In addition, as shown in Fig. 10(c)–(g), both p-polarized light and s-polarized light support a large incident angle with 60°. The independence of polarization and incidence angle mentioned above is due to the high symmetry of the membrane structure, which provides robust conditions for practical applications.
Fig. 10. Emissivity of the range of 3–14 µm. Insensitive to polarization on (a) “off state” and (b) “on state”. (c)-(g) Insensitive to incident angle on “off state” and “on state” under transverse magnetic (TM) polarization wave and transverse electric (TE) polarization wave.
4. Conclusion
In summary, this paper proposes a layered device with multifunctional deep modulation characteristics for IR stealth, thermal imaging, and radiative cooling based on the phase-change material GST through an inverse design method. The inverse design method eliminates the tedious process of considering the adjustment of parameters and automatically finds the structural parameters that are most compatible with the target. As an IR stealth device, the emissivity in the IR detection band can be highly suppressed while being compatible with thermal management in the NAW. It has the function of adjustable absorption for thermal imaging detection and good cooling performance when used as a radiative cooling device. It is worth mentioning that the design in this paper is a highly symmetric multilayer film system structure without adding additional micro-nano structures, which bypasses many complex nano-processing preparation flows facilitating large-area preparation and integration. Due to the nature of phase-change materials, the ability to achieve functional switching without changing structural parameters is also one of its advantages. In addition, the design in this paper has good insensitivity properties to polarization and supports large angle (60°) incidence, which is crucial for practical applications.
Funding
National Key Research and Development Program of China (2022YFF0706005); National Natural Science Foundation of China (12272407, 60907003, 61805278, 62275269, 62275271); Program for New Century Excellent Talents in University (NCET-12-0142); Natural Science Foundation of Hunan Province (13JJ3001); Foundation of NUDT (JC13-02-13, ZK17-03-01); China Postdoctoral Science Foundation (2018M633704); Key research & development program of Guangxi (AB22080048); Science and Technology Major Project of Guangxi (2020AA21077007, 2020AA24002AA); the Postgraduate Scientific Research Innovation Project of Hunan Province (CX20230009).
Disclosures
The authors declare no conflicts of interest.
Data availability
The data that support the findings of this study are available from the corresponding author upon reasonable request.
Supplemental document
See Supplement 1 for supporting content.
References
1. X. Jiang, H. Yuan, X. He, et al., “Implementing of infrared camouflage with thermal management based on inverse design and hierarchical metamaterial,” Nanophotonics 12(10), 1891–1902 (2023). [CrossRef]
2. X. Jiang, Z. Zhang, H. Ma, et al., “Tunable mid-infrared selective emitter based on inverse design metasurface for infrared stealth with thermal management,” Opt. Express 30(11), 18250–18263 (2022). [CrossRef]
3. Y. Chen, J. Mandal, W. Li, et al., “Colored and paintable bilayer coatings with high solar-infrared reflectance for efficient cooling,” Sci. Adv. 6(17), eaaz5413 (2020). [CrossRef]
4. Y. Ke, Q. Zhang, T. Wang, et al., “Cephalopod-inspired versatile design based on plasmonic VO2 nanoparticle for energy-efficient mechano-thermochromic windows,” Nano Energy 73, 104785 (2020). [CrossRef]
5. T. Tian, X. Huang, Y. Xu, et al., “A Wideband Energy Selective Surface With Quasi-Elliptic Bandpass Response and High-Power Microwave Shielding,” IEEE Trans. Electromagn. Compat. (2023).
6. F. Qin, X. Chen, Z. Yi, et al., “Ultra-broadband and wide-angle perfect solar absorber based on TiN nanodisk and Ti thin film structure,” Sol. Energy Mater. Sol. Cells 211, 110535 (2020). [CrossRef]
7. H. Liu, K. Yu, K. Zhang, et al., “Pattern-free solar absorber driven by superposed Fabry–Perot resonances,” Phys. Chem. Chem. Phys. 25(15), 10628–10634 (2023). [CrossRef]
8. X. Jiang, H. Yuan, D. Chen, et al., “Metasurface based on inverse design for maximizing solar spectral absorption,” Adv. Opt. Mater. 9(19), 2100575 (2021). [CrossRef]
9. J. Yang, X. Zhang, X. Zhang, et al., “Beyond the visible: bioinspired infrared adaptive materials,” Adv. Mater. 33(14), 2004754 (2021). [CrossRef]
10. H. K. Woo, K. Zhou, S. K. Kim, et al., “Visibly transparent and infrared reflective coatings for personal thermal management and thermal camouflage,” Adv. Funct. Mater. 32(38), 2201432 (2022). [CrossRef]
11. D. G. Baranov, Y. Xiao, I. A. Nechepurenko, et al., “Nanophotonic engineering of far-field thermal emitters,” Nat. Mater. 18(9), 920–930 (2019). [CrossRef]
12. D. C. Kohlgraf-Owens, S. Sukhov, L. Greusard, et al., “Optically induced forces in scanning probe microscopy,” Nanophotonics 3(1-2), 105–116 (2014). [CrossRef]
13. X. Wang, L. Liu, and Z. Tang, “Infrared dim target detection based on fractal dimension and third-order characterization,” Chin. Opt. Lett. 7(10), 931–933 (2009). [CrossRef]
14. L. Xiao, H. Ma, J. Liu, et al., “Fast Adaptive Thermal Camouflage Based on Flexible VO2/Graphene/CNT Thin Films,” Nano Lett. 15(12), 8365–8370 (2015). [CrossRef]
15. J. Zhang, R. Wei, M. ElKabbash, et al., “Thin-film perfect infrared absorbers over single- and dual-band atmospheric windows,” Opt. Lett. 45(10), 2800–2803 (2020). [CrossRef]
16. N. Lee, T. Kim, J. S. Lim, et al., “Metamaterial-Selective Emitter for Maximizing Infrared Camouflage Performance with Energy Dissipation,” ACS Appl. Mater. Interfaces 11(23), 21250–21257 (2019). [CrossRef]
17. T. Maier and H. Brueckl, “Multispectral microbolometers for the midinfrared,” Opt. Lett. 35(22), 3766–3768 (2010). [CrossRef]
18. W. Ma, D. Jia, Y. Wen, et al., “Diode-based microbolometer with performance enhanced by broadband metamaterial absorber,” Opt. Lett. 41(13), 2974–2977 (2016). [CrossRef]
19. Y. Tang, D. Meng, Z. Liang, et al., “An Infrared Metamaterial Broadband Absorber Based on a Simple Titanium Disk with High Absorption and a Tunable Spectral Absorption Band,” Ann. Phys. 532(9), 2000145 (2020). [CrossRef]
20. K.-T. Lin, H.-L. Chen, Y.-S. Lai, et al., “Silicon-based broadband antenna for high responsivity and polarization-insensitive photodetection at telecommunication wavelengths,” Nat. Commun. 5(1), 3288 (2014). [CrossRef]
21. S. Bhattacharyya, S. Ghosh, D. Chaurasiya, et al., “Bandwidth-enhanced dual-band dual-layer polarization-independent ultra-thin metamaterial absorber,” Appl. Phys. A 118(1), 207–215 (2015). [CrossRef]
22. S. Daniel and P. Bawuah, “Highly polarization and wide-angle insensitive metamaterial absorber for terahertz applications,” Opt. Mater. 84, 447–452 (2018). [CrossRef]
23. C. Wu, B. Neuner, G. Shvets, et al., “Large-area wide-angle spectrally selective plasmonic absorber,” Phys. Rev. B 84(7), 075102 (2011). [CrossRef]
24. D. Zhao, A. Aili, Y. Zhai, et al., “Radiative sky cooling: Fundamental principles, materials, and applications,” Appl. Phys. Rev. 6(2), 021306 (2019). [CrossRef]
25. A. P. Raman, M. A. Anoma, L. Zhu, et al., “Passive radiative cooling below ambient air temperature under direct sunlight,” Nature 515(7528), 540–544 (2014). [CrossRef]
26. Y. Zhou, Z. Qin, Z. Liang, et al., “Ultra-broadband metamaterial absorbers from long to very long infrared regime,” Light: Sci. Appl. 10(1), 138 (2021). [CrossRef]
27. S. Liu, Z. Ma, J. Pei, et al., “A review of anomalous refractive and reflective metasurfaces,” Nanotechnology and Precision Engineering (NPE) 5(2), 025001 (2022). [CrossRef]
28. A. Singh, H. Srivastava, R. Chari, et al., “Effect of the orientation of non-spherical metal nanoparticle with respect to light polarization on its transient optical response,” Nanotechnology and Precision Engineering (NPE) 6(2), 023005 (2023). [CrossRef]
29. E. Hou, Z. Qin, Z. Liang, et al., “Dual-band metamaterial absorber with a low-coherence composite cross structure in mid-wave and long-wave infrared bands,” Opt. Express 29(22), 36145–36154 (2021). [CrossRef]
30. D. Costantini, A. Lefebvre, A. L. Coutrot, et al., “Plasmonic Metasurface for Directional and Frequency-Selective Thermal Emission,” Phys. Rev. Appl. 4(1), 014023 (2015). [CrossRef]
31. A. Raponi, M. Ciarniello, F. Capaccioni, et al., “Infrared detection of aliphatic organics on a cometary nucleus,” Nature Astronomy 4(5), 500–505 (2020). [CrossRef]
32. S.-R. Wu, K.-L. Lai, and C.-M. Wang, “Passive temperature control based on a phase change metasurface,” Sci. Rep. 8(1), 7684 (2018). [CrossRef]
33. H. Ghasemi, G. Ni, A. M. Marconnet, et al., “Solar steam generation by heat localization,” Nat. Commun. 5(1), 4449 (2014). [CrossRef]
34. J. W. Stewart, J. H. Vella, W. Li, et al., “Ultrafast pyroelectric photodetection with on-chip spectral filters,” Nat. Mater. 19(2), 158–162 (2020). [CrossRef]
35. X. Liu and W. J. Padilla, “Thermochromic Infrared Metamaterials,” Advanced materials (Deerfield Beach, Fla.) 28(5), 871–875 (2016). [CrossRef]
36. Y. Liu, R. Huang, and Z. Ouyang, “Terahertz absorber with dynamically switchable dual-broadband based on a hybrid metamaterial with vanadium dioxide and graphene,” Opt. Express 29(13), 20839–20850 (2021). [CrossRef]
37. A. Hendaoui, N. Émond, M. Chaker, et al., “Highly tunable-emittance radiator based on semiconductor-metal transition of VO2 thin films,” Appl. Phys. Lett. 102(6), 061107 (2013). [CrossRef]
38. H. Kim, Y. Kim, K. S. Kim, et al., “Flexible Thermochromic Window Based on Hybridized VO2/Graphene,” ACS Nano 7(7), 5769–5776 (2013). [CrossRef]
39. E. Petronijevic and C. Sibilia, “Thin films of phase change materials for light control of metamaterials in the optical and infrared spectral domain,” Opt. Quantum Electron. 52(2), 110 (2020). [CrossRef]
40. D.-X. Zhu, W.-D. Shen, and H.-Y. Zhen, “Anisotropic optical constants of in-plane oriented polyfluorene thin films on rubbed substrate,” J. Appl. Phys. 106(8), 084504 (2009). [CrossRef]
41. S. Raoux, W. Wełnic, and D. Ielmini, “Phase Change Materials and Their Application to Nonvolatile Memories,” Chem. Rev. 110(1), 240–267 (2010). [CrossRef]
42. B. Gholipour, J. Zhang, K. F. MacDonald, et al., “An All-Optical, Non-volatile, Bidirectional, Phase-Change Meta-Switch,” Adv. Mater. 25(22), 3050–3054 (2013). [CrossRef]
43. S. Abdollahramezani, O. Hemmatyar, H. Taghinejad, et al., “Tunable nanophotonics enabled by chalcogenide phase-change materials,” Nanophotonics 9(5), 1189–1241 (2020). [CrossRef]
44. K.-K. Du, Q. Li, Y.-B. Lyu, et al., “Control over emissivity of zero-static-power thermal emitters based on phase-changing material GST,” Light: Sci. Appl. 6(1), e16194 (2016). [CrossRef]
45. X. Jiang, Z. Zhang, D. Chen, et al., “Tunable multilayer-graphene-based broadband metamaterial selective absorber,” Appl. Opt. 59(35), 11137–11145 (2020). [CrossRef]
46. Y. Ying, B. Ma, J. Yu, et al., “Whole LWIR Directional Thermal Emission Based on ENZ Thin Films,” Laser Photonics Rev. 16(8), 2200018 (2022). [CrossRef]
47. Q.-Y. Wen, Y.-S. Xie, H.-W. Zhang, et al., “Transmission line model and fields analysis of metamaterial absorber in the terahertz band,” Opt. Express 17(22), 20256–20265 (2009). [CrossRef]
48. W. C. Snyder, Z. Wan, and X. Li, “Thermodynamic constraints on reflectance reciprocity and Kirchhoff’s law,” Appl. Opt. 37(16), 3464–3470 (1998). [CrossRef]
49. “IR Transmission Spectra and Gemini Observatory,”, retrieved http://<url><url>www.gemini.edu</url></url>/?q=node/10789.
50. K. Shportko, S. Kremers, M. Woda, et al., “Resonant bonding in crystalline phase-change materials,” Nat. Mater. 7(8), 653–658 (2008). [CrossRef]
51. J.-W. Park, S. H. Eom, H. Lee, et al., “Publisher's Note: Optical properties of pseudobinary GeTe, Ge2Sb2Te5, GeSb2Te4, GeSb4Te7, and Sb2Te3 from ellipsometry and density functional theory,” Phys. Rev. B 80(2009).
52. E.-R. Sittner, K. S. Siegert, P. Jost, et al., “(GeTe)x–(Sb2Te3)1–x phase-change thin films as potential thermoelectric materials,” Physica Status Solidi (a) 210(1), 147–152 (2013). [CrossRef]
53. R. L. Cotton and J. Siegel, “Stimulated crystallization of melt-quenched Ge2Sb2Te5 films employing femtosecond laser double pulses,” J. Appl. Phys. 112(12), 123520 (2012). [CrossRef]
54. Z. Zhang, J. Yang, W. Bai, et al., “All-optical switch and logic gates based on hybrid silicon-Ge2Sb2Te5 metasurfaces,” Appl. Opt. 58(27), 7392–7396 (2019). [CrossRef]
55. H. Li, “Refractive index of alkaline earth halides and its wavelength and temperature derivatives,” J. Phys. Chem. Ref. Data 9(1), 161–290 (1980). [CrossRef]
56. V. B. Rajkumar, Y. Du, S. Liu, et al., “Measurements of the melting points, liquidus, and solidus of the Mo, Ta, and MoTa binary alloys using a novel high-speed pyrometric technique,” International Journal of Refractory Metals and Hard Materials 93, 105335 (2020). [CrossRef]
57. M. Seo, J. Kim, H. Oh, et al., “Printing of Highly Vivid Structural Colors on Metal Substrates with a Metal-Dielectric Double Layer,” Adv. Opt. Mater. 7(13), 1900196 (2019). [CrossRef]
58. Y. Kim, C. Kim, and M. Lee, “Parallel Laser Printing of a thermal emission Pattern in a phase-change thin film Cavity for Infrared Camouflage and security,” Laser Photonics Rev. 16(3), 2100545 (2022). [CrossRef]
59. M. Pan, Y. Huang, Q. Li, et al., “Multi-band middle-infrared-compatible camouflage with thermal management via simple photonic structures(Article),” Nano Energy 69, 104449 (2020). [CrossRef]
60. C. Yuan, J. Huang, Y. Dong, et al., “Record-High Transparent Electromagnetic Interference Shielding Achieved by Simultaneous Microwave Fabry–Pérot Interference and Optical Antireflection,” ACS Appl. Mater. Interfaces 12(23), 26659–26669 (2020). [CrossRef]
61. J. J. Foley, C. Ungaro, K. Sun, et al., “Design of emitter structures based on resonant perfect absorption for thermophotovoltaic applications,” Opt. Express 23(24), A1373–A1387 (2015). [CrossRef]
62. J. Feldmann, N. Youngblood, C. D. Wright, et al., “All-optical spiking neurosynaptic networks with self-learning capabilities,” Nature 569(7755), 208–214 (2019). [CrossRef]
63. M. Song, D. Wang, Z. A. Kudyshev, et al., “Enabling Optical Steganography, Data Storage, and Encryption with Plasmonic Colors,” Laser Photonics Rev. 15(3), 2000343 (2021). [CrossRef]
64. M. M. Hossain and M. Gu, “Radiative Cooling: Principles, Progress, and Potentials,” Adv. Sci. 3(7), 1500360 (2016). [CrossRef]
65. A. R. Gentle and G. B. Smith, “Radiative Heat Pumping from the Earth Using Surface Phonon Resonant Nanoparticles,” Nano Lett. 10(2), 373–379 (2010). [CrossRef]
66. E. Rephaeli, A. Raman, and S. Fan, “Ultrabroadband photonic structures to achieve high-performance daytime radiative cooling,” Nano Lett. 13(4), 1457–1461 (2013). [CrossRef]
67. B. Zhao, Y. Shi, J. Wang, et al., “Near-complete violation of Kirchhoff’s law of thermal radiation with a 0.3 T magnetic field,” Opt. Lett. 44(17), 4203–4206 (2019). [CrossRef]
68. L. Peng, D. Liu, H. Cheng, et al., “A multilayer film based selective thermal emitter for infrared stealth technology,” Adv. Opt. Mater. 6(23), 1801006 (2018). [CrossRef]
69. S. Liang, F. Xu, W. Li, et al., “Tunable smart mid infrared thermal control emitter based on phase change material VO2 thin film,” Appl. Therm. Eng. 232, 121074 (2023). [CrossRef]
70. C. Quan, S. Gu, J. Zou, et al., “Phase change metamaterial for tunable infrared stealth and camouflage,” Opt. Express 30(24), 43741–43751 (2022). [CrossRef]
