LBO$(LiB_3O_5)$ is an important nonlinear optical material which shows wide transparency range from 155 nm to 3.2㎛. However the study of second-order cascading effect and nonlinear refractive index has not been reported.
In this thesis, the noncritical phase matching condition and dependency of phase mismatch ΔkL on temperature were investigated. Based on the temperature tuning curve, the nonlinear transmittance and the nonlinear phase shift induced by the cascading effect in LBO crystals were measured using a traditional phase measurment method, the ellipsometric method. A Nd:YAG laser operating at 1.064 ㎛ with the pulse width 33ps was used.
When the incident fundamental beam intensity was 54.8 MW/㎠, the nonlinear transmittance was measured to be 0.7 at the phase-matching condition and the nonlinear phase shift due to the cascading effect was 0.13 radian and the corresponding nonlinear refractive index was estimated to be $8.5\times10^{-14} cm^2/W$ at ΔkL=3.0.
