Simulation And Experimental Study Of The Characteristics Of Subwavelength Metal Terahertz Transmission Array Structure

With the development of femtosecond laser technology and lithography, the generation of terahertz pulses and the application of terahertz device are progressing rapidly. Especially, because of the extraordinary transmission effect shown by the sub-wavelength periodic array structure, these structures show some special features on the application of terahertz device. Additional, the size of these structures are too small to measure in experiment directly, so they must be deposited in the substrate. Firstly, in this essay the influence of substrate materials on the terahertz transmission characteristics of metallic microstructures has been studied by numerical simulation and experiment. Secondly, the spectral characteristics of two-dimensional sub-wavelength metal wire gratings structure and asymmetric cross-shaped structures have been studied by the experiment measurements, which provide an essential reference for the research on the manufacturing of small terahertz device.The main issues in this essay include the following points:1. We have investigated how the different substrate materials and its thicknesses affect the terahertz transmission of the rectangular-hole metal structure. By the numerical simulation, we found that the transmission peak shifts into the lower frequency with increasing of the substrate thicknesses. Comparing Si and PTFE as the substrate materials, it is found that Si substrates have the higher dielectric constant and its peak shift more obvious.2. The terahertz transmission of four series asymmetric cross-shaped structures have been studied and we find that the lengths, cycle and the offset from the side to the center may influence the characters of terahertz transmission.3. The numerical simulation and experiment of the characteristics of three series two-dimensional metallic grating is carried out. The results show that reducing the width and increasing the gap between the metal wires of the well-shaped grid may enhance the high-pass of filter function; altering the length of the array of complementary square metallic pill may change the range of the low-pass of filter function; the cross wire-hole array achieves a band-pass of filter function and with the change of the metal wires, the frequency and bandwidth of the band-pass filter can be modulated.