The Filtering Property Of Micro-Nano Structure And Applied Basic Research

The micro-nano structure,which can selectively reflect,transmit and absorb the incident lights,has important applications in fields as green printing,electromagnetic shielding,stealth,flexible optoelectronics,photovoltaic solar cells and other fields.In this paper,to satisfy the requirement of large-scale structure color,green printing,upmarket anti-counterfeiting and electromagnetic shielding,face the problem that the existing structure color can’t be fabricated in large-area.Based on the accurately manipulating of light in the visible and near-infrared range,two kinds of large-area broadband absorbers,and two types of large-area color filters are numerically and experimently proposed.The main contents and innovations of this thesis are listed as following:(1)In the area of broadband absorber.Firstly,we present an omnidirectional broadband absorber whose dielectric-metal-dielectric layers are modulated by cylinder arrays.The simultaneous excitation of surface plasmon resonance and localized surface plasmon resonance affords an average optical absorption of 0.97 for the wavelength range of 400-1100 nm,and its absorptions show an angular tolerance of up to 60°.Moreover,it exhibits considerably lower emissivity(weak absorption-0.08)in the midinfrared range,which makes it promising for energy harvesting.In addition,for the application of thermal photovoltaic solar cells,we experimentally develop a metasurface with-87%absorptivity of unpolarized,ultraviolet,visible and near-infrared light covering almost the entire solar spectrum(250-2250 nm),and low hemispherical thermal emittance-29%for long-infrared range(5-13μm).The metasurface incorporates dielectric cylinder arrays,a titanium nitride and a silicon nitride layers.The metasurface absorber we proposed here has the thinnest thickness under the premise of ultrabroad bandwidth among all optically TiN-based absorbers.(2)In the color filter field.At first,this study develops a large-area pixelated filter that can achieve colors covering the entire visible range with a fixed period under normal incidence.Vivid colors as blue,green,and yellow(peak efficiency of～0.6)are experimentally achieved based on a Fano-resonance by altering the overlay’s refractive index.Furthermore,the feasibility of this device in large-area color printing(3 cm × 3 cm)and index sensors(a Figure of merit of 254)are discussed in detail.And then,we design and fabricate large-area color filter incorporating a dielectric grating,an aluminum nano-patch array and a silicon nitride layer.Its asymmetric geometry produces a strong symmetry-broken color rendering effect,wherein different transmitted colors are observed under perpendicular planes with the same incident angle.Originated from surface plasmonic resonance and guide mode resonances,peak transmission efficiency-0.6 is achieved.Furthermore,distinctive colors covering the entire visible range are generated by varying the grating period.The experimental results are coincident with the simulations,showing great potential in various applications such as large area color printings and anti-counterfeit certifications.(3)Most of the existing structure colors are fabricated by electron beam lithography,which is small in area and expensive in fabrication.In this paper,the continuously variable spatial frequency photolithography,which is much faster,low-cost,and can be easily scaled up by roll-to-roll manufacturing,allows us to fabricate structure colors at large-area scales.