Low power third harmonic generation and all-optical switching by graphene surface plasmons

In this study, we aimed at optimizing the nonlinear properties of the guiding structure of graphene surface plasmon polaritons. The structure is a graphene–metal hybrid waveguide with applicable mode confinement. Focusing electromagnetic power in the graphene sheet improves the harmonic conversion efficiency (0.2% (−27 dB)) and high self-phase modulation. The third harmonic generation phase-matching condition was satisfied in three-dimensional simulations for longer harmonic generation length. Low loss performance is vital for devices that operate in the terahertz regime (0.3–30 THz), because of the low efficiency offered by the available terahertz pulse generation methods. In this study, low loss propagation was achieved by engineering the chemical potential of graphene. Finally, a frequency-selective all-optical switch was designed by placing a subwavelength resonator in the waveguide. Self-phase modulation enabled optical control of the frequency-selective switch. (paper)