KI-shaped terahertz metamaterial with tunable filtering, attenuating, and sensing characteristics

This study proposes a versatile KI-shaped terahertz metamaterial (KITM) for opto-logic operation, which is highly sensitive in environmental sensing applications. KITM consists of a fixed I-shaped metallic bar and a movable K-shaped structure that allows dynamic tuning. The optical responses of KITM are insensitive to the distance between the K-shaped and I-shaped structures. By changing the distance between the lifted K-shaped structure and substrate from 0 to 2.4 μm, the resonance is blueshifted from 0.74 to 1.10 THz and its intensities are attenuated from 0.70 to 0.15 in transverse electric mode. When changing the distance from 0 to 0.8 μm, KITM shows optical switching characteristics at 0.69 THz in transverse magnetic mode. By interpreting the vertical and horizontal displacements of reconfigurable K-shaped structure as binary inputs, KITM can support logic gate operations, such as “AND,” “NAND,” and “OR.” When KITM is exposed to the ambient background, its sensitivity to background refractive index is between 76 and 120 GHz/RIU. These properties highlight that KITM has potential in THz communication and biochemical sensing applications.