Tunable multiresonance using complementary circular metamaterial.

We present a design of a tunable infrared (IR) resonator by using complementary circular metamaterial (CCM). CCM is composed of concentric rings. It exhibits superior characteristics of narrow multiresonance generated by the coupling between two adjacent concentric rings in the IR wavelength range. An effective modulation of reflection spectra can be realized by changing the height of each concentric ring. By slightly elevating the concentric rings, the corresponding resonances can be switched between on and off states, and the resonances become more sensitive to the surrounding refraction index. The figure of merit (FOM) is 10.91 for CCM exposed on the surrounding environment with different refraction indices. The correlation coefficient is 0.998. The proposed CCM design provides potential applications in refraction index sensors and exhibits the possibility for future multichannel IR switches, environmental sensors, bandpass filters, wavelength-division multiplexing, and so on.