Determination of focal length photoinduced lens in ionic liquids

We study nonlinear optical properties of 1-buthyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF
₄
]), 1-ethyl-3-methylimidazolium Bis((trifluoromethyl)sulfonyl)imide ([EMIM][TF
₂
N]), 1-ethyl-3-methylimidazolium trifluoroacetate ([EMIM][CF
₃
COO]), 1-buthyl-3-ethylimidazoliumtrifluoroacetate ([BMIM][CF
₃
COO]), 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF
₄
]) and 1-buthyl-3-methylimidazolium Bis((trifluoromethyl)sulfonyl)imide ([BMIM][TF
₂
N]). We determinated the focal length photo-induced lens using z-scan technique by adjusting the characteristic curves of nonlinear refraction index. This indicated the presence of thermal and electronic effects.