Femtosecond Laser-Induced Vanadium Oxide Metamaterial Nanostructures and the Study of Optical Response by Experiments and Numerical Simulations

Abstract

Surface patterning is a popular approach to produce photonic metasurfaces that are tunable when electro-optic, thermooptic, or magneto-optic materials are used. Vanadium oxides (V y O x ) are well-known phase change materials with many applications, especially when used as tunable metamaterial photonic structures. Particularly, VO 2 is a well-known thermochromic material for its near-room-temperature phase transition from the insulating to the metallic state. One-dimensional (1D) VO 2 nanograting structures are studied by numerical simulation, and the simulation results reveal that the VO 2 nanograting structures could enhance the luminous transmittance (T lum ) compared with a pristine flat VO 2 surface. It is worth mentioning that T lum is also polarization-dependent, and both larger grating height and smaller grating periodicity give enhanced T lum , particularly at TE polarization in both insulating (20 °C) and metallic (90 °C) states of VO 2 . Femtosecond laser-patterned VO 2 films exhibiting nanograting structures with an average periodicity of ≈500−700 nm have been fabricated for the first time to enhance thermochromic properties. Using X-ray photoelectron spectroscopy, it is shown that at the optimum laser processing conditions, VO 2 dominates the film composition, while under extra processing, the existence of other vanadium oxide phases such as V 2 O 3 and V 2 O 5 increases. Such structures show enhanced transmittance in the near-infrared (NIR) region, with an improvement in NIR and solar modulation abilities (ΔT NIR = 10.8%, ΔT sol = 10.9%) compared with a flat VO 2 thin film (ΔT NIR = 8%, ΔT sol = 10.2%). The slight reduction in transmittance in the visible region is potentially due to the scattering caused by the imperfect nanograting structures. This new patterning approach helps understand the polarization-dependent optical response of VO 2 thin films and opens a new gateway for smart devices.

Superhydrophobic VO2 Nanoparticle/PDMS Composite Films as Thermochromic, Anti-icing, and Self-Cleaning Coatings

“…As previously reported by our group and other groups, VO 2 as a typical thermochromic material exhibits the dramatic self-regulating ability of optical transmission/reflection with temperature changes, which has attracted extensive attention for the development of energyefficient strategies and renewable resources. 17,18,20,23,26,28,59 In this work, the large-scale production of the multifunctional thermochromic film was achieved with a 4 in. diameter.…”

“…16−18 Nevertheless, due to its intrinsic physical properties, the application of VO 2 nanoparticles (NPs) to energysaving smart windows still faces a series of challenges, such as undesired/noncustomizable color, instability, biosafety, and integration technologies. 19−22 Various approaches have been applied to address these issues, including doping, 14 antire-flection coating, 23 biomimetic structuring, 24 compositing, 25 photonic structuring, 26 kirigami-inspired structuring, 27 and so forth. However, the trade-off relationship among the three major indexes luminous transmission (T lum ), solar modulation (ΔT sol ), and phase transition temperature (τ c ) is observed in most cases, which is extraordinarily challenging to balance.…”

Research on the Response Characteristics of Vanadium Pentoxide Film to the Irradiation of Ultrafast Pulsed Laser

“…The valence state and composition information of the sample were obtained by XPS, and the results are shown in Figure 2 . The binding energy for V2p 3/2 peak was 517.039 eV, which corresponded to the characteristic binding energy of V 5+ , proving that the film prepared is V 2 O 5 film [ 19 ].…”

Achieving Rewritable Fluorescent Patterning on Dye-Doped Polymers Using Programmable Laser Direct Writing

“…As one of the most common lasers, carbon dioxide (CO 2 ) laser has been widely used in food, medicine, machinery and electronics, aerospace, and other fields with the characteristics of low-cost, simple operation, and high photothermal conversion efficiency. − The interaction between CO 2 laser and materials is mainly manifested as the thermal effect, which can be used in the surface treatment, cutting, patterning, and perforation of materials. − Recently, laser direct writing (LDW) as new technology has been widely used for the surface patterning of metals, ceramics, plastics, and other materials. LDW exhibits great potential in designing patterns, especially for polymers, in that the high-energy laser beam irradiates the materials to generate instantaneous high temperature, leaving permanent patterns on the polymers’ surface by carbonization, discoloration, vaporization, or foaming. − Typical applications are to make logos, images, texts, two-dimensional codes, or barcodes to ensure the identification and traceability of various commodities. Although the applications of polymers’ LDW are very extensive, people have always hoped that the patterns produced by lasers have more functions to achieve personal performance and anticounterfeiting functions further.…”