Design of Arm Asymmetry Structure Based on Metamaterial for THz Sensor

Abstract

Metamaterials which can induce Fano resonance have a promising application. Thanks to the Fano resonance, a window will emerge in the transmission spectral of resonator. Both radiative damping and non-radiative damping exist in the window. Non-radiative damping is very easy to be interfered, a little change in the background can result in big change of the window, so it is promising for sensor application. Here, an Arm asymmetric metamaterial has been proposed. In X-axis direction the arm is asymmetry, the Fano resonance can be tuned by changing the asymmetric factor $S$. The sum of $S_{11}^{2}+S_{21}^{2}=0.239$ when $S=5\mu \mathrm{m}$, energy have been loss since non-radiative damping, so the sensor will be sensitive. And when $S\geq 12\mu \mathrm{m}$, a length of the spectral of window is above −3 dB. So, the resonator can be used as switch. A column of biased diodes has been proposed to add in the metamaterial. Changing the electric potential difference between biased diode, on and off of biased diodes can be controlled. So, the switch on and off state is realized. And the length of arm is decided by how many biased diodes are needed to be ON, the passband of switch can be tuned.