Polyethylene terephthalate cubic nonlinearity coefficient measurement with a modified Z-scan technique

Abstract

A modified Z-scan technique was used to measure the polyethylene terephthalate (PET) cubic nonlinearity coefficient n2 at two different wavelengths (1030 and 515 nm). The proposed technique was benchmarked with the well-studied fused silica (FS) sample. The obtained n2 values for fused silica n2(FS,1030nm)=1.72, n2(FS,515nm)=3.1 and for PET n2(PET,1030nm)=11.5 in the units of 10−7cm2/GW agree well with the previously published data. The nonlinear coefficient for PET at the wavelength of 515 nm n2(PET,515nm)=26.5⋅10−7cm2/GW was obtained in this work, presumably, for the first time, and demonstrates high nonlinearity of PET in the visible band. The proposed modified Z-scan technique exhibits a factor of three better sensitivity with respect to the traditional one, which was crucial for PET measurements due to its low damage threshold.