Direct observation of the transient thermal-lensing effect using the phase-object Z-scan technique

Abstract

A phase-object (PO) Z-scan technique, which can conveniently distinguish the transient thermal-lensing effect from the third-order nonlinear refraction, is described. The PO Z-scan trace of the transient thermal-lensing effect shows a valley–peak shape that is very different from the single-valley (peak) shape of the pure negative (positive) third-order nonlinearity. The nonlinear refraction of the ${\mathrm{C}}_{70}$/toluene solution is investigated by using the PO Z scan with $8\mathrm{ns}$ pulses at $532\mathrm{nm}$ wavelength as a test.

© 2009 Optical Society of America