Fig. 2: DFG signal and electrically tunable plasmons.
From: Nonlinear co-generation of graphene plasmons for optoelectronic logic operations
a–c Phase-matching condition (white dashed line) and graphene’s plasmonic dispersion for |EF | = 0.1, 0.2 and 0.3 eV. The red, yellow and blue dots mark the ‘frequency-momentum’ position of the nonlinearly generated plasmons. White solid lines: Phonon resonances of the silica substrate. Colour bar: normalized intensity. d–f Measured ΔIDFG peaks. Red, yellow and blue curves plot the cases when |EF | = 0.1, 0.2 and 0.3 eV, respectively. In these panels, the grey curves show the results measured in a D-shaped fibre without graphene for comparison. Colour bar of the maps shows normalized plasmonic intensity. g Pump transmission in the GDF device. The pump transmission first increases due to saturable absorption, and then decreases due to nonlinear DFG consumption. h The total ΔIDFG increases linearly with the pump power.
