Shant Arakelyan

Memory metamaterials allowing persistent tuning of their unusual electromagnetic responses are an emerging group of artificial electromagnetic materials. Here, the memory metamaterial operating at microwave frequency based on the hybrid resonance of the metamaterial‐ferromagnetic system is reported. It is demonstrated that the hybrid resonance can be tuned reversibly as a function of frequency and amplitude of the input microwave signal. The principle underlying the persistent hybrid resonance tuning is the adaptive structural modification of the magnetic domain structure for the input microwave signal.

The visualization of the microwave radiation intensity in the middle-field region by the thermo-elastic optical indicator microscopy (TEOIM) system for the sub-skin-depth metallic layers was performed. An indicator with the 10 nm Al deposition for the 50 GHz microwave radiation intensity visualization was used. Modeled simulation results were in good agreement with the experimental data. A defect discovering technique of the sub-skin-depth conductive layers was proposed. For the 20 nm Al indicator the scratched defect by the TEOIM visualization was successfully discovered. The relation of the Al layer thickness and its skin-depth was around 1:18.

The visualization of carbon fibers polyether ether ketone (PEEK) composite material heating for a grounded coplanar waveguide and a stepped impedance low-pass filter by the thermal camera is performed. The purpose of such visualization is to characterize electromagnetic field influence on the diagonally anisotropic composite material and find out its application opportunity. COMSOL Multiphysics simulation has been done in order to understand heating principles and origin. Experimental results were in a good agreement with simulations and they showed that the characteristics of the microstrip structures can be modulated/tuned by simple rotation of the composite material. Finally, a tunable application by the carbon/PEEK composite material for the microstrip low-pass filter was developed due to the microwave absorption selectivity dependence on the composite material orientation.

A high resolution imaging of the temperature and microwave near field can be a powerful tool for the non-destructive testing of materials and devices. However, it is presently a very challenging issue due to the lack of a practical measurement pathway. In this work, we propose and demonstrate experimentally a practical method resolving the issue by using a conventional CCD-based optical indicator microscope system. The present method utilizes the heat caused by an interaction between the material and an electromagnetic wave, and visualizes the heat source distribution from the measured photoelastic images. By using a slide glass coated by a metal thin film as the indicator, we obtain optically resolved temperature, electric, and magnetic microwave near field images selectively with a comparable sensitivity, response time, and bandwidth of existing methods. The present method provides a practical way to characterize the thermal and electromagnetic properties of materials and devices under various environments.