Modulation of THz radiation via enhanced Dirac plasmon-dual phonon interaction

Abstract

Imaging with terahertz (THz) radiation is a crucial technique that promotes its applications in security inspection, crack detection, biomedical imaging, and so forth. THz modulation is one of the critical factors (others include generation, propagation, and detection) of the THz fast imaging technique. In this work, an efficient THz radiation modulator is realized based on the as-grown Bi2Se3 nanowires. Different from the conventional metamaterials or plasmonic devices, fabrication of subwavelength structures is unnecessary in this manipulation. The modulation is facilitated via synergistic Fano-type interaction of topological surface plasmons with two phonons in Bi2Se3 nanowires. The comprehensive control of the modulation is realized in a direct optical manner. A high modulation depth of 1826% has been demonstrated in this modulator. The realization of such a THz modulator based on an as-grown system indicates the possibility of the modulation extricating from fabrication of complicated postgrowth micro/nanostructures.