Optimization of Characteristics of Reconfigurable Nonlinear THz and IR Devices Based on 1D Reflective Graphene Gratings

The performances of THz third harmonic sources and THz-IR up-converters, IR-THz down-converters (THz sources) based on the 1D reflective graphene gratings are numerically investigated by solving the nonlinear boundary diffraction problems. First, the linear performances of the 1D reflective gratings of graphene ribbons on the dielectric substrate (GGs), containing the N-layers dielectric mirror (GGDMs) and the gold film mirror (GGMMs) having a resonant character in the case of the incident p-polarized waves were calculated in the THz and IR bands. It is shown that the GGMMs manifests itself in almost complete absorption at the resonant frequencies of the fundamental and higher-order surface plasmon polaritons modes compared to the GGs. At the second stage, the nonlinear performances of THz third harmonic sources were obtained. It is shown that the GGDM-based THz source demonstrates an increase in the third harmonic intensity of reflective wave R
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by more than 10 dB compared to the GG and GGMM-based THz sources. Next, the nonlinear performances of IR-THz down-converters (THz sources) and THz-IR up-converters were obtained. It is shown that the use of mirrors allows an increase in the level of conversion by 25 dB compared to the GGs without mirrors.