Articles written in Bulletin of Materials Science

• An ultrafast laser micromachined broadband terahertz frequency selective surface

The purpose of this paper is to focus on the frequency selective surface (FSS) filter structure which exhibits a broadband frequency response operating in the terahertz (THz) frequency regime. The achievement of the broadbandfrequency response has been accomplished by means of only invoking the FSS structure excluding the presence of a ground plane and also excluding the multilayered FSS technique. The FSS filter is simulated using CST Microwave Studio. This simulation has been carried out using Teflon as the substrate which is a dielectric over which the conductive material gold with a thickness of 2 $\mu$m is coated in which the FSS filter structure is designed with periodic hexagonal aperture unit cells. The structure of the proposed frequency selective surface filter helps in achieving a broadband frequency response witha bandwidth of 300 GHz centred at 0.36 THz. The designed FSS structure is a bandpass filter and it exhibits the most imperative properties of angle resolvability and polarization insensitivity. The fabrication of the same has been carried outusing the laser micromachining process.

• Terahertz dual-band/broadband metamaterial absorber enabled by SiO$_2$: polyimide and PET dielectric substrates with absorption characteristics

A compact dual-band/broadband polarization in-sensitive terahertz (THz) metamaterial absorber (MMA) is discussed in this article. It consists of a simple planar structure as a unit cell and an optically transparent indium tin oxide(ITO) ground plane, which are separated by a 50 $\mu$m dielectric substrate. We designed three combinations of MMA, which are ITO–SiO$_2$–ITO, ITO–polyimide–ITO and ITO–polyethylene terephthalate (PET)–ITO for the same planar structure. The proposed structure has dual-band absorbance with peak absorptivity of[98% for all three given combinations. By changing the substrate of the structure, the resonant frequency and bandwidth of the absorber structure is varied and by adjusting the design parameters, broadband absorbance is achieved for the same planar structure. The numerical simulation of the absorber shows that the broadband absorptivity is >98% for all three substrates. Polyimide, PET and SiO$_2$ based absorbers are demonstrated with bandwidth of 0.467, 0.527 and 0.6 THz with covered broadband frequency rangeof 0.390–0.857, 0.407–0.934 and 0.433–1.03 THz, respectively. ITO–PET–ITO absorber structures also possess optical transparency. These bandwidths are convenient and compatible with electronic and magnetic sources in the terahertzregion. This study provides applications in THz detection, sensing, bolometric imaging, and stealth and communication systems. All three absorbers have greater absorbance characteristics for transverse electric and transverse magnetic polarizations. The proposed structure is working well for wide angles of incident and polarization angles wave up to 90$^{\circ}$.

• # Bulletin of Materials Science

Volume 44, 2021
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020