Fig. 3: Third harmonic emission spectra and nonlinear power dependence.
From: Plasmonic mid-infrared third harmonic generation in germanium nanoantennas
a The excitation spectra and b the corresponding third harmonic emission spectra from single resonant double-rod antennas at excitation wavelengths of 10.7, 12, and 14 µm (red, blue and green, respectively). c The nonlinear power dependence of the THG emission on a double-logarithmic scale for a 12 µm excitation wavelength (circles). The line of cubic proportionality proves the third harmonic character of the radiation and shows the start of saturating behavior for high excitation powers beyond 1.5 mW
