Fabrication of frequency-selective surface by picosecond laser direct writing

In this paper, a terahertz (THz) frequency-selective surface (FSS) is fabricated through picosecond (ps) laser direct writing on the silicon-based silver film. The time-domain spectroscopy (TDS) technique is used to test its electromagnetic modulation performance. Based on the finite-difference time-domain method, CST microwave studio 2016 was used to simulate its resonance characteristic. By optimizing the process parameters, the square ring structures on the FSS with the size error below 2% are fabricated. It is found that the center frequencies of the experimental and simulated resonance peaks are nearly both at 0.293 THz, and the transmission is about 0.01%. From the simulation results, when the size error is controlled below 2 mu m, the resonant frequency shift is about 2.2 GHz. Combining the simulation and experimental results, if the size error of inner square is controlled below 2%, it has little effect on the THz metasurfaces' modulation performance. By optimizing the laser scanning strategy and processing parameters, ps laser direct writing provides a new choice for the convenient fabrication of THz metamaterials.