Extraction of dielectric and magnetic material properties for a periodic hole array THz filter

2015-08-28
Özkarslıgil, Zeynep Tuğçe
Nebioğlu, Mehmet Ali
Takan, Taylan
Altan, Hakan
With the increase in optical applications in the terahertz frequency range there is a greater need for devices that work at these frequencies. One such device which has applications which range from spectroscopy to imaging is the band pass filter. The frequency selective nature of this component can be used for filtering noise during signal processing or can be even used for reducing radiation background levels for imaging purposes [1, 2]. The simplest form of this filter structure has been shown to be that of a free-standing metal sheet with a hole array. The frequency selective nature of the filter is realized by changing the structural parameters of the hole array with respect to the propagating input THz wave. Due to the sub-millimeter wave nature of the radiation the patterns are easier to fabricate for low frequency terahertz radiation applications (<1THz). Here, by using a high power Yb:doped pulsed nanosecond fiber laser system with exceptional beam quality, aluminum metal surfaces were machined with high precision leading to a high quality band pass filter that was shown to work in the terahertz frequency range [3]. We modeled the THz transmission through the the structure that was produced using FDTD simulation tools and also characterized them using the existing home-built time-domain terahertz spectrometers in our laboratories. Results of FDTD simulations are found to be consistent with transmission coefficient which is obtained from the experiment. In order to understand the efficiency of the composite structure which can be described as a frequency selective surface, the electrical permittivity (ε) and magnetic permeability (μ) is extracted from the transmission and reflection simulations [4]. The significance of these values is discussed with respect to the width and transmission observed for the fabricated and measured filter.
Citation Formats
Z. T. Özkarslıgil, M. A. Nebioğlu, T. Takan, and H. Altan, “Extraction of dielectric and magnetic material properties for a periodic hole array THz filter,” presented at the PHOTONICA 2015 (24 - 28 Ağustos 2015), Belgrad, Sırbistan, 2015, Accessed: 00, 2021. [Online]. Available: http://www.photonica.ac.rs/photonica2015/UserFiles/File/BookOfA/BookOfAbstracts.pdf.