Theory of surface sum frequency generation spectroscopy

Energy Conservation and the Manley-Rowe Relations in Surface Nonlinear-Optical Spectroscopy

“…For instance, for simple model flat surfaces like jellium [5] or continuous dipolium [7] surfaces, a tangential field does not induce a response in the normal direction; hence ͑x S ͒ Ќkk IJK 0. On the other hand, ͑x S ͒ kkЌ IJK fi 0, since a normal external field E Ќ K induces a screening charge which is moved by the tangential field E k J and thus gives rise to a tangential current at frequency v K 1 v J [10,11]. As schematically illustrated in Fig.…”

“…An enormous progress has been achieved in experimental applications of the surface nonlinear-optical spectroscopy to study different systems [4]. On the other hand, although a number of theoretical studies of surface SHG [5][6][7][8] and a few extensions of the theory to surface SFG spectroscopy [9][10][11] have been reported, there are still various unsolved problems in understanding the fundamental physics of the surface nonlinear interactions. For threewave interactions in centrosymmetric bulk media the energy relations were first considered by Pershan [12], who constructed the free energy for transparent centrosymmetric systems with quadrupole-allowed nonlinearity.…”

“…(3) However, examination of the existing theoretical results [10,11] shows that the surface nonlinear susceptibility x S does not obey the overall permutation symmetry (3). For instance, for simple model flat surfaces like jellium [5] or continuous dipolium [7] surfaces, a tangential field does not induce a response in the normal direction; hence ͑x S ͒ Ќkk IJK 0.…”

“…For SFG, this parametrization is generalized to quantities that depend on the three frequencies involved, namely, a IJK and b IJK . According to the jellium model [10,11] the parameter b IJK takes the value 21, but this need not be true for other systems. However, a more general statement can be made based on the relations derived here.…”

Giant spectral transformations in plasmon-enhanced difference-frequency generation with polychromatic light

“…To evaluate the DFW, we use the hydrodynamic model of the difference-frequency surface susceptibility developed in [44]. ( )…”