Cascading of χ(2) for χ(3) Nonlinearities

The cascading of second order nonlinearities (χ(2): χ(2) to induce a nonlinear phase distortion on the input beam has recently received considerable attention[1,2] We estimate that materials with large second order nonlinearities (≃102 pm/V) will give rise to effective nonlinear refractive indices, n 2 eff , of 10–12 to 10–10 esu. These nonlinearities are truly nonresonant and can be in a lossless spectral region (i.e. loss determined by impurities and defects). An important difference between this nonlinearity and a true χ(3) nonlinearity is that the sign is readily changed by, for example, changing the phase matching condition.