In centrosymmetric media, in addition to the third- and fifth-order nonlinearity, a cascaded [Formula Presented] nonlinearity contributes to the nonlinear refraction. The described effect takes place when the input beam is involved in nearly phase-matched third-harmonic generation. The nonlinear phase shift produced by this new cascaded nonlinearity is comparable to the nonlinear phase shift caused by the direct third-order nonlinearity [Formula Presented] A new analytical approach, low depletion approximation, was developed and used to study the cascaded third-order processes in the conditions of not very high third-harmonic conversion coefficients. At higher conversion coefficients the effect was studied by numerical simulations. The presence of a seeded third-harmonic wave gives another possibility of controlling the additional phase shift of the fundamental wave. The conditions for stationary copropagation of the fundamental and the generated wave are presented.
Physical Review A - Atomic, Molecular, and Optical Physics
Sprott School of Business

Saltiel, S. (S.), Koynov, K. (K.), Tzankov, P. (P.), Boardman, A. (A.), & Tanev, S. (1998). Nonlinear phase shift as a result of cascaded third-order processes. Physical Review A - Atomic, Molecular, and Optical Physics, 57(4), 3028–3035. doi:10.1103/PhysRevA.57.3028