2019). Nonlinear optical response of the alpha-T-3 model due to the nontrivial topology of the band dispersion. Physical Review B, 100 (3), 035440-1-035440-16. Nonlinear optical response of the alpha-T-3 model due to the nontrivial topology of the band dispersion AbstractWe study the electronic contribution to the nonlinear optical response of the α-T3 model. This model is an interpolation between a graphene (α = 0) and dice (α = 1) lattice. Using a second-quantized formalism, we calculate the first-and third-order responses for a range of α and chemical potential values as well as considering a band gap in the first-order case. Conductivity quantization is observed for the first-order, while higher-order harmonic generation is observed in the third-order response with the chemical potential determining which applied field frequencies both quantization and harmonic generation occur at. We observe a range of experimentally accessible critical fields between 102-106 V/m with dynamics depending on α, μ, and the applied field frequency. Our results suggest an α-T3-like lattice could be an ideal candidate for use in terahertz devices.We study the electronic contribution to the nonlinear optical response of the α-T 3 model. This model is an interpolation between a graphene (α = 0) and dice (α = 1) lattice. Using a second-quantized formalism, we calculate the first-and third-order responses for a range of α and chemical potential values as well as considering a band gap in the first-order case. Conductivity quantization is observed for the first-order, while higher-order harmonic generation is observed in the third-order response with the chemical potential determining which applied field frequencies both quantization and harmonic generation occur at. We observe a range of experimentally accessible critical fields between 10 2 -10 6 V/m with dynamics depending on α, μ, and the applied field frequency. Our results suggest an α-T 3 -like lattice could be an ideal candidate for use in terahertz devices.

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We demonstrate a strong and anisotropic photomixing effect in an electronic system whose energy-momentum dispersion is parabolic in the ? direction and linear in the ? direction, such as a TiO 2 /VO 2 multilayered structure. The third-order photoresponses along the linear and parabolic directions have been analyzed and determined quantitatively. We have found a remarkable tunability of the mixing efficiency along the parabolic direction by a small electric field in the linear direction, up to two orders of magnitude. In the terahertz (THz) regime, the third-order response is comparable to the linear response under an applied field of 10 3-10 4 V/cm. Additionally, the nonlinear response persists at room temperature. The results may have applications where different current responses are required along different directions in the THz regime. We demonstrate a strong and anisotropic photomixing effect in an electronic system whose energy-momentum dispersion is parabolic in the ? direction and linear in the ? direction, such as a TiO2/VO2 multilayered structure. The third-order photoresponses along the linear and parabolic directions have been analyzed and determined quantitatively. We have found a remarkable tunability of the mixing efficiency along the parabolic direction by a small electric field in the linear direction, up to two orders of magnitude. In the terahertz (THz) regime, the third-order response is comparable to the linear response under an applied field of 103-104 V/cm. Additionally, the nonlinear response persists at room temperature. The results may have applications where different current responses are required along different directions in the THz regime.

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