Second order cascading is the process by which the exchange of energy between fundamental wavc and second harmonic wave leada to effective third order nonlinear optical effect such as nonlinear phase shifts.
In this thesis, nonlinear phase shifts induced by second order cacading in $LBO(LiB_3O_5)$ crystals were measured for various phase mismatching conditions as increasing input intensity. The ellipsometric method was used with a Nd:Yag laser operating at 1.064 ㎛ with the pulse width 33 ps.
Near the phase matching condition Nonlinear phase shift is rapidly and stepwise increased. However in the limit of negligible fundamental depletion, that is, in the large phase mismatch nonlinear phase shift is linearly increased and it is possible to introduce an effective nonlinear index of refraction $n_2^{eff}$. When the input intensity was 2.2 GW/㎠, $n_2^{eff}$ was estimated to be 3.5×$10^{-15}$ ㎠/W at ΔkL = 10π.