Full text loading...
Schematic energy level diagrams describing the difference-frequency generation on metal surface (a) without and (b) with localized surface plasmons excitation. The Dirac notations |a> and |b> denote two virtual energy states, |g> the ground state, and |LSP> an eigenstate of the localized surface plasmons. The frequencies of the pump light, the probe light, and the idler light are ω 1, ω 2, and ω 3, respectively. The gray area in (b) represents the approximate range of the eigenstates of the localized surface plasmons for one of the two samples we investigate, which covers |b> and replaces it with |LSP>. Vertical arrows connecting the energy states are thicker in (b) than in (a), indicating an increase in nonlinear efficiency.
Transmission spectra of two MgF2-Au films measured by a visible spectrometer. The thickness of the MgF2 layer is 200 nm in both films, while the mass thicknesses of the gold layers are 4 and 40 nm, respectively. The localized surface plasmons band for the 4-nm film ranges approximately from 500 to 950 nm, covering the wavelength of the probe light in pump-probe measurements.
Time-dependent differential transmission ΔT/T for the two MgF2-Au films. The pump and the probe fluences are 1.1 and 2.9 μJ/cm2, respectively, for both films. (a) The differential transmission for the 4-nm film. (b) The differential transmission around zero delay for both films.
Power dependence of the DFG efficiency for the 4-nm film. The pump fluence is 1.1 μJ/cm2, while the probe fluence changes from 2.9 to 33.5 μJ/cm2. (a) Three representative differential transmission curves with the probe fluence at 2.9 (red), 15.3 (blue) and 33.5 μJ/cm2 (magenta), respectively. (b) The height of the DFG peak versus the probe fluences. (c) Average power of the DFG light versus the probe fluences. The red dashed line shows predicted dependence with the damping being very weak or absent. In both (b) and (c), the error bar on each point represents the deviation of five measurements.
Article metrics loading...