Rk. Meyer et al., NONLINEAR-OPTICAL SUSCEPTIBILITIES MEASURED IN POLY(PARA-PHENYLENE CUMULENE[3]) BY THE Z SCAN TECHNIQUE, Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals, 256, 1994, pp. 605-610
Optical nonlinear susceptibilities were measured in Poly(paraphenylene
cumulene[3]) (PPC) at 590nm and 1064nm. Both the real and imaginary p
arts of chi((3)) were evaluated with the Z scan technique using closed
and open apertures, respectively. Open aperture Z scans on PPC at 590
nm displayed a negative Im chi((3)), indicating saturation at this ene
rgy, as expected due to the close proximity to the absorption band edg
e. Due to accumulated long time effects, closed aperture scans gave er
roneously high Re chi((3)) values and second hyperpolarizabilities of
-3.9x10(-11)esu and -4.67x10(-28)esu, respectively.(1) The presence of
a long time effect was verified by mechanically modulating the 1 kHz
pulse train and observing radical changes in Re chi((3)) while peak an
d average powers remained constant.