Bi2O2Se for broadband terahertz wave switching

Many modern terahertz systems require dynamic manipulation of a terahertz wave. We proposed a terahertz wave switch based on a B i 2 O 2 S e / S i structure. The transmittance and conductivity characteristics of the B i 2 O 2 S e in a terahertz region have been measured by terahertz time-domain spectroscopy and analyzed using the Drude model. An ON–OFF switching speed as fast as 2 MHz and an extinction ratio as high as 17.7 dB was achieved at an external laser irradiance of 1.3 W / c m 2 . The switching characteristics of the device can be explained by the accumulation of carriers at the interface that induces terahertz wave intense absorption. Our approach can effectively be used to realize a wide range of dynamically tunable terahertz functional devices. This makes its use viable for a range of communication, imaging, and sensing applications.