Design and fabrication of sub-terahertz filter using maskless femto second laser micromachining process

Anovel mask lessand rapid fabrication of frequency selective surface on the low-cost Copper/Polyimide substrate for sub-terahertz filter applications is discussed in this paper.The geometry of the unit cell is in hexagonal geometry with rectangular strips on its sides.The proposed frequency selective surface exhibits minimum reflection (S11) characteristics at 106.75 GHz. Parametric studies on the width of rectangular strip (W), periodicity of the unit cell (P), angle of incidence (theta) and thickness of copper layer (Ct)are conducted to demonstrate its effect on the transmission and reflection characteristics of the filter.A prototype of the proposed frequency selective surface is fabricated using femto second laser micromachining processand tested using Terahertz frequency domain spectroscopysystem. Measured and simulated results are compared where an agreeable correspondence is observed.