The complex tensor components of the nonlinear susceptibility χ(2) of C(100) and of the interface

Generation of microwave fields in cavities with laser-excited nonlinear media: competition between the second- and third-order optical nonlinearities

“…It is convenient to introduce the complex amplitude ξ(t) =Q + iω c Q. Its evolution according to equation (18) is given by the well known formula…”

“…Numerical evaluations can differ by many orders of magnitude, since different authors gave rather different values of the surface second order nonlinear coefficients for the diamond. A model considered in [17] resulted in the values ofχ (2) up to 10 −20 m 2 /V in the SI units, while experimental data given in [18] corresponded to the values from 10 −26 m 2 /V to 6 × 10 −24 m 2 /V. To transform these values to the Gaussian units one has to multiply them by the factor 3 × 10 4 /(4π) [15].…”

“…This case has already been analyzed in [14], so here we show the main results of the study with some modifications. Considering the excitation of the fundamental cavity mode, we omit hereafter the index n in equation (18) and write…”

“…In this connection, it is necessary to have in mind that real crystals always possess nonzero second-order nonlinear susceptibility coefficients χ (2) . Although it is known that χ (2) must be zero in crystals possessing the inversion symmetry [15], this is true, as a matter of fact, in the idealized case of infinite ideal crystals, whereas real crystals of finite size do show second-order nonlinear effects, either due to the presence of impurities/defects or due to the loss of inversion symmetry in the regions near the surface [16][17][18][19][20]. The generation of microwave radiation in the cavity containing different nonlinear materials with high χ (2) coefficients, irradiated with intense infrared pulse trains, was reported in [21,22].…”