Search

Devices designed to dynamically control the transmission, reflection, and absorption of terahertz (THz) radiation are essential for the development of a broad range of THz technologies. A viable approach utilizes materials which undergo an insulator‐to‐metal transition (IMT), switching from transmissive to reflective upon becoming metallic. However, for many applications, it is undesirable to have spurious reflections that can scatter incident light and induce noise to the system. We present an electrically actuated, broadband THz switch which transitions from a transparent state with low reflectivity, to an absorptive state for which both the reflectivity and transmission are strongly suppressed. Our device consists of a patterned high‐resistivity silicon metamaterial layer that provides broadband reflection suppression by matching the impedance of free space. This is integrated with a VO2 ground plane, which undergoes an IMT by means of a DC bias applied to an interdigitated electrode. THz time domain spectroscopy measurements reveal an active bandwidth of 700 GHz with suppressed reflection and more than 90% transmission amplitude modulation with a low insertion loss. We utilize finite‐difference time domain (FDTD) simulations in order to examine the loss mechanisms of the device, as well as the sensitivity to polarization and incident angle. This device validates a general approach toward suppressing unwanted reflections in THz modulators and switches which can be easily adapted to a broad array of applications through straightforward modifications of the structural parameters. [ABSTRACT FROM AUTHOR]

In this paper, a low‐cost metamaterial (MM) absorber is proposed using 3‐dimensional (3D) printing technology. The unit cell of the proposed MM absorber is motivated from a swastika symbol to minimize the footprint size. For further miniaturization, the unit cell is 3D printed by stacking two blocks. The conductive top patterns are realized by painting with a silver ink. The proposed MM absorber consists of 2 × 4 unit cell array which is loaded in the rectangular waveguide. Its absorptivity is simulated and measured to demonstrate the performance. The simulated and measured absorptivity at 1.91 GHz are 99% and 92%, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT In this letter, a transparent electromagnetic absorber that provides stability for an angle of incidence and wide absorption bandwidth is presented using resistive frequency selective surface as circuit analogue structure at X-band. The transparency of proposed structure is implemented using a transparent resistive film made of an indium-tin-oxide (ITO) and soda-lime glass as dielectric spacer. Reflection loss characteristics for different angles of both TE and TM polarizations are presented through simulations. We then fabricated the proposed structure to verify the simulation results. The comparisons between the simulation and measured results show good agreements. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2023-2025, 2015 [ABSTRACT FROM AUTHOR]