Study On Transparent Electromagnetic Shielding Material Based On Subwavelength-grid Structure

Transparent electromagnetic shielding,which possesses the ability to transmit the visible light and shield the microwave(or radio wave)has extensive applications in the fields of national defense,communication,and aerospace.Transparent conducting films(TCF)fall into the contradiction between transparency and shielding effectiveness(SE)for lacking in degrees of designing freedoms.Sub-wavelength materials(SWM),as a kind of artificial construction,can dominate the electromagnetic response by the arrangement of the geometry.SWM can manipulate the phase,amplitude and polarization state of the electromagnetic wave.Metallic mesh,which shares thin shape and high designing freedom from SWM,is expected to exceed the limited performance of traditional TCFs.However,SWM-based metallic mesh still suffers from issues like imperfect theoretical framework,low shielding effectiveness,and low transparency.Moreover,demands for large areas and small feature sizes bring new challenges to the manufacturing methods.Hence,this work focus on metallic mesh then has further research on the SWM-based transparent electromagnetic shielding materials to study the designing methodology and processing technique.The main contents are as follows:1,A optimization scheme is proposed based on the numerical calculation method and equivalent circuit model.This scheme is fast and efficient to simulate the photoelectric performance of the material,which is expected to improve the theoretical designing method.Metallic mesh with a nano-scale feature size is proven to surpass the micromesh considering the optical transmittance,SE,shielding bandwidth,and distribution of high-order diffractive energies.Moreover,the proposed nanomesh possesses moderate robustness with the incident angle from 0 to 50 degrees.2,A manufacturing method is proposed by combing the ultraviolet photolithography and ion beam etching technique.A copper nanomesh with a small feature size of 850 nm is fabricated on a large aperture of 100 mm.SE above 40 dB is performed on the wideband from 0.5 to 40 GHz while the transparency of 85% is achieved at 550 nm and the average visible transmittance of 83.2% is achieved.The nanomesh is transparent in the visible and near-infrared regions.These outstanding performances will meet the strict demands of the operating ambient.At last,a method based on the ion beam etching technique is proposed to optimize the manufacturing method,which is beneficial to shrink the feature sizes.The proposed fabricating methodology may broaden the way to apply the SWM-based metallic mesh to optoelectronic devices.