Abstract
Phase-transition materials provide exciting opportunities for controlling optical properties of photonic devices dynamically. Here, we systematically investigate the infrared emission from a thin film of vanadium dioxide (VO2). We experimentally demonstrate that such thin films are promising candidates to tune and control the thermal radiation of an underlying hot body with different emissivity features. In particular, we studied two different heat sources with completely different emissivity features, i.e. a black body-like and a mirror-like heated body. The infrared emission characteristics were investigated in the 3.5–5.1 μm spectral range using the infrared thermography technique which included heating the sample, and then cooling back. Experimental results were theoretically analyzed by modelling the VO2 film as a metamaterial for a temperature range close to its critical temperature. Our systematic study reveals that VO2 thin films with just one layer 80 nm thick has the potential to develop completely different dynamic tuning of infrared radiation, enabling both black-body emission suppression and as well as mirror emissivity boosting, in the same single layer device. Understanding the dynamics and effects of thermal tuning on infrared emission will benefit wide range of infrared technologies including thermal emitters, sensors, active IR filters and detectors.
Highlights
Phase-transition materials provide exciting opportunities for controlling optical properties of photonic devices dynamically
We experimentally investigate infrared emission from a single VO2 thin film on sapphire substrate using infrared thermography technique[30,31]
The system under investigation consists of an 80 nm thick VO2 film layer (d ~ λ/50 at central wavelength λ = 4 μm) on c-plane sapphire substrate by pulsed-laser-deposition (PLD), allowing high transmission through the entire operational wavelength range of the infrared camera (3.3–5.1 μm)
Summary
Phase-transition materials provide exciting opportunities for controlling optical properties of photonic devices dynamically. The possibility to tune the spectral features of a device, triggered by a thermal, electrical or optical stimulation, paves the way for many applications such as perfect infrared a bsorbers[1,2,3,4], smart intelligent window c oatings[5,6], thermal rectification d evices[7] or diodes/rectifiers[8] Thermochromic materials, such as niobium dioxide ( NbO2), vanadium sesquioxide ( V2O3), and vanadium dioxide ( VO2) undergo an abrupt phase transition from semiconductor to metallic state at a specific phase transition temperature[9,10,11]. Efficient terahertz modulation performance was experimentally demonstrated, in terms of strong modulation depth of transmittance (83%), using 120 nm thick films[16]
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