Terahertz metallic waveguide with meta-holes for bidirectional conversion between two-dimensional guided waves and free-space waves.

The conversion between guided and free-space waves is crucial for achieving integrated terahertz (THz) communication and signal processing. Herein, a bidirectional conversion mechanism is proposed for bridging two-dimensional (2D) guided waves and free-space waves, which is demonstrated by the wave manipulation of a metallic waveguide with meta-holes (MWMH). Compared with the conventional conversion between one-dimensional guided waves and free-space waves, in the proposed bidirectional conversion process, meta-holes can arbitrarily manipulate the phase of THz waves in higher dimensions, which enables stronger beam-manipulation capability and a higher gain. When used as a transmitting antenna, the MWMH exhibits excellent performance, i.e., a high gain (33.3 dBi), a high radiation efficiency (∼90%), and flexible beam manipulation. When the MWMH is reversely employed as a receiving antenna to obtain the focus of 2D guided waves, it achieves a gain of 27 dB and a focusing efficiency of 50.4%. The measured results for both the transmitting and receiving antennas agree well with the simulation results. The proposed bidirectional conversion mechanism facilitates the development of THz integrated photonic devices and is promising for application in the sixth-generation mobile communication, radar detection, and nondestructive testing. [ABSTRACT FROM AUTHOR]