Thermal radiation from a black body increases with the fourth power of absolute temperature (T4), an effect known as the Stefan–Boltzmann law. Typical materials radiate heat at a portion of this ...limit, where the portion, called integrated emissivity (εint), is insensitive to temperature (|dεint/dT| ≈ 10−4 °C–1). The resultant radiance bound by the T4 law limits the ability to regulate radiative heat. Here, an unusual material platform is shown in which εint can be engineered to decrease in an arbitrary manner near room temperature (|dεint/dT| ≈ 8 × 10−3 °C–1), enabling unprecedented manipulation of infrared radiation. As an example, εint is programmed to vary with temperature as the inverse of T4, precisely counteracting the T4 dependence; hence, thermal radiance from the surface becomes temperature‐independent, allowing the fabrication of flexible and power‐free infrared camouflage with unique advantage in performance stability. The structure is based on thin films of tungsten‐doped vanadium dioxide where the tungsten fraction is judiciously graded across a thickness less than the skin depth of electromagnetic screening.
Unprecedented manipulation of infrared radiation is achieved by an unusual material platform based on thin films of vanadium dioxide where tungsten is judiciously graded doped across a thickness of <100 nm. The platform enables various infrared applications including a flexible and power‐free infrared camouflage with unique advantages, as well as a novel technology named “infrared decoy.”
Miniaturized spectrometers in the mid-infrared (MIR) are critical in developing next-generation portable electronics for advanced sensing and analysis. The bulky gratings or detector/filter arrays in ...conventional micro-spectrometers set a physical limitation to their miniaturization. In this work, we demonstrate a single-pixel MIR micro-spectrometer that reconstructs the sample transmission spectrum by a spectrally dispersed light source instead of spatially grated light beams. The spectrally tunable MIR light source is realized based on the thermal emissivity engineered via the metal-insulator phase transition of vanadium dioxide (VO
). We validate the performance by showing that the transmission spectrum of a magnesium fluoride (MgF
) sample can be computationally reconstructed from sensor responses at varied light source temperatures. With potentially minimum footprint due to the array-free design, our work opens the possibility where compact MIR spectrometers are integrated into portable electronic systems for versatile applications.
Miniaturized spectrometers in the mid-infrared (MIR) are critical in developing next-generation portable electronics for advanced sensing and analysis. The bulky gratings or detector/filter arrays in ...conventional micro-spectrometers set a physical limitation to their miniaturization. In this work, we demonstrate a single-pixel MIR micro-spectrometer that reconstructs the sample transmission spectrum by a spectrally dispersed light source instead of spatially grated light beams. The spectrally tunable MIR light source is realized based on the thermal emissivity engineered via the metal-insulator phase transition of vanadium dioxide (VO
2
). We validate the performance by showing that the transmission spectrum of a magnesium fluoride (MgF
2
) sample can be computationally reconstructed from sensor responses at varied light source temperatures. With potentially minimum footprint due to the array-free design, our work opens the possibility where compact MIR spectrometers are integrated into portable electronic systems for versatile applications.
The unique correspondence between mathematical operators and photonic elements in wave optics enables quantitative analysis of light manipulation with individual optical devices. Phase‐transition ...materials are able to provide real‐time reconfigurability of these devices, which would create new optical functionalities via (re)compilation of photonic operators, as those achieved in other fields such as field‐programmable gate arrays (FPGA). Here, by exploiting the hysteretic phase transition of vanadium dioxide, an all‐solid, rewritable metacanvas on which nearly arbitrary photonic devices can be rapidly and repeatedly written and erased is presented. The writing is performed with a low‐power laser and the entire process stays below 90 °C. Using the metacanvas, dynamic manipulation of optical waves is demonstrated for light propagation, polarization, and reconstruction. The metacanvas supports physical (re)compilation of photonic operators akin to that of FPGA, opening up possibilities where photonic elements can be field programmed to deliver complex, system‐level functionalities.
An all‐solid, rewritable metacanvas is demonstrated by exploiting the hysteretic phase transition of vanadium dioxide. On the metacanvas, nearly arbitrary metaphotonic devices can be rapidly and repeatedly written and erased. The writing is performed with a low‐power laser below 90 °C. Dynamic manipulation of optical waves for light‐beam steering, polarization control, and holographic reconstruction is achieved with the metacanvas.
Featuring high photon energy and short wavelength, ultraviolet (UV) light enables numerous applications such as high‐resolution imaging, photolithography, and sensing. In order to manipulate UV ...light, bulky optics are usually required, and hence do not meet the fast‐growing requirements of integration in compact systems. Recently, metasurfaces have shown unprecedented control of light, enabling substantial miniaturization of photonic devices from terahertz to visible regions. However, material challenges have hampered the realization of such functionalities at shorter wavelengths. Herein, it is experimentally demonstrated that all‐silicon (Si) metasurfaces with thicknesses of only one‐tenth of the working wavelength can be designed and fabricated to manipulate broadband UV light with efficiencies comparable to plasmonic metasurface performance in infrared (IR). Also, for the first time, photolithography enabled by metasurface‐generated UV holograms is shown. Such performance enhancement is attributed to increased scattering cross sections of Si antennas in the UV range, which is adequately modeled via a circuit. The new platform introduced here will deepen the understanding of light–matter interactions and introduce even more material options to broadband metaphotonic applications, including those in integrated photonics and holographic lithography technologies.
Practical metasurfaces across the broadband ultraviolet range based on silicon, which was previously considered not useful in the ultraviolet, are demonstrated. High‐efficiency beam steering and photolithography enabled by metasurface‐generated ultraviolet holograms are achieved for the first time. Such performance enhancement is due to the large permittivity‐induced high scattering efficiency, which is well explained with a circuit model.
We propose an all-solid-state tunable Bragg filter with a phase transition material as the defect layer. Bragg filters based on a vanadium dioxide defect layer sandwiched between silicon ...dioxide/titanium dioxide Bragg gratings are experimentally demonstrated. Temperature dependent reflection spectroscopy shows the dynamic tunability and hysteresis properties of the Bragg filter. Temperature dependent Raman spectroscopy reveals the connection between the tunability and the phase transition of the vanadium dioxide defect layer. This work paves a new avenue in tunable Bragg filter designs and promises more applications by combining phase transition materials and optical cavities.
Thermal radiation from a black body increases with the fourth power of absolute temperature (T4), an effect known as the Stefan-Boltzmann law. Typical materials radiate heat at a portion of this ...limit, where the portion, called integrated emissivity (εint), is insensitive to temperature (|dεint /dT| ≈ 10-4 °C-1). The resultant radiance bound by the T4 law limits the ability to regulate radiative heat. Here, an unusual material platform is shown in which εint can be engineered to decrease in an arbitrary manner near room temperature (|dεint /dT| ≈ 8 × 10-3 °C-1), enabling unprecedented manipulation of infrared radiation. As an example, εint is programmed to vary with temperature as the inverse of T4 , precisely counteracting the T4 dependence; hence, thermal radiance from the surface becomes temperature-independent, allowing the fabrication of flexible and power-free infrared camouflage with unique advantage in performance stability. In this work, the structure is based on thin films of tungsten-doped vanadium dioxide where the tungsten fraction is judiciously graded across a thickness less than the skin depth of electromagnetic screening.
Lacking the atmosphere for temperature neutralization, objects in outer space without thermal control undergo large temperature swings. Effective temperature management technologies (TMTs) are ...essential to avoid undesirable effects caused by extreme thermal conditions. However, existing high-performance TMTs impose additional burden on the limited mass and power budgets of spacecrafts. Very recently, temperature-adaptive solar coatings (TASCs) and temperature-adaptive radiative coatings (TARCs) emerged as novel light-weight, energy-free temperature-regulation approaches for terrestrial objects with excellent thermal performance. Here, we simulate and present the great potential of TASCs and TARCs as future passive TMTs for space objects. A case study of a geosynchronous satellite with body-mounted solar panels covered by TARC exhibits an interior temperature swing as small as 20.3°C–25.6°C in an orbital period even with solar eclipses. These findings provide insight into the superior performance of TASCs and TARCs in space and will promote their application in extraterrestrial missions.
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•TASCs and TARCs are promising for passive temperature management in outer space•TASCs and TARCs do not bring in extra mass, volume, or power burdens to spacecrafts•The thermal performance of TASCs and TARCs is simulated with satellite thermal models•Simulations show a temperature swing as low as 5.3°C in a 1U-CubeSat covered by TARCs
Advanced high-performance passive temperature management technologies without additional mass/volume/power burdens are required for space exploration. Dong et al. propose use of emerging temperature-adaptive solar or radiative coatings (TASCs or TARCs, respectively) on space objects and simulate their temperature-regulation performance with satellite thermal models, demonstrating the potential of TARCs and TARCs in outer space.
The atomic thickness and flatness allow properties of 2D semiconductors to be modulated with influence from the substrate. Reversible modulation of these properties requires an “active,” ...reconfigurable substrate, i.e., a substrate with switchable functionalities that interacts strongly with the 2D overlayer. In this work, the photoluminescence (PL) of monolayer molybdenum disulfide (MoS2) is modulated by interfacing it with a phase transition material, vanadium dioxide (VO2). The MoS2 PL intensity is enhanced by a factor of up to three when the underlying VO2 undergoes the thermally driven phase transition from the insulating to metallic phase. A nonvolatile, reversible way to rewrite the PL pattern is also demonstrated. The enhancement effect is attributed to constructive optical interference when the VO2 turns metallic. This modulation method requires no chemical or mechanical processes, potentially finding applications in new switches and sensors.
Photoluminescence of monolayer MoS2 is reversibly modulated by interfacing MoS2 with a phase transition material, VO2. A nonvolatile, reversible way to rewrite the photoluminescence pattern by a laser beam is also demonstrated. This modulation method requires no chemical or mechanical processes, potentially finding applications in new switches, displays, and sensors.
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