Microfabrication of Low Cost Frequency Selective Surface for Terahertz Wave by Laser Ablation

Abstract

A method of fabricating and characterizing terahertz frequency selective surface filters from a low-cost silver adhesive tape has been reported in this paper. The proposed filter was initially evaluated numerically using the method of moment’s simulation and verified experimentally by terahertz time-domain spectroscopy technique. The numerical results show that the cross aperture frequency selective surface has angle-resolved and polarization independent operation. The proposed silver adhesive tape and conventional copper-based frequency selective surface have been fabricated using a laser micromachining process. A 20 ns-pulsed laser operating at 1064 nm wavelength was used to create the desired structure by ablation mechanism in the copper film. The pattern ablated by the laser is a cross-shaped slit on copper and silver adhesive tape. The patterned structure was designed to resonate at 0.25 THz by the cross-arm structure. The fabricated structure shows the peak transmittance of 90% with a full-width half maximum of 48% with respect to the resonance. The adhesive tape based frequency selective surface provides similar transmission characteristics compared to a conventional frequency selective surface.