Terahertz wave modulators in organic/Si bilayers

We realized optically controllable active terahertz (THz) modulators with extremely high modulation efficiencies, using organic/silicon hybrid structures. The rapid photo-induced electron transfer in thermally annealed C₆₀/silicon bilayers enables the realization of modulation efficiency up to 98%. Furthermore, we demonstrate the broadband modulation of THz waves due to the change cutoff condition caused by the formation of efficient charge separation by the photo-excitation in the structures. The realization of near-perfect modulation efficiency of THz waves opens up the possibilities of utilizing active modulators for THz spectroscopy and communications.