Enhanced transmission through a Si-InSb-Si bimaterial subwavelength grating with slits at the terahertz range

Two groups of grating structures with subwavelength slits, composed of different materials are investigated to realize an extraordinary optical transmission (EOT) phenomenon. We find that the transmittance of a InSb grating at the frequencies corresponding to surface plasmon (SP) excitation is almost zero, which verifies the negative role of SPPs in transmission anomalies. And optical characteristics of these bimaterial grating structures are thoroughly analyzed by the transmittance spectrum and optical field intensity. In addition, the greatly enhanced transmission was achieved by changing the temperature, doping concentration, and the geometrical parameters of the InSb-Si-InSb bimaterial grating structure, and the optimized transmission can reach almost 94%. Besides, it is verified that the position of the peaks is strongly dependent on the depth of the slits. Last, we demonstrate the transmission of the InSb-Si-InSb bimaterial grating is higher than its counterparts, and the collimated beaming effect is also realized through it. These features make this structure an excellent candidate for plasmonic components in all optical and optoelectronic fields.