Polarization-dependent Z-scan characterization for optical nonlinearity in pyran dye

Polarization-dependent Z-scan characterization is made for DCM (4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran) dye encapsulated in a polymer matrix (DCM/PMMA). A continuous wave Ar+ laser beam operating at ∼514 nm wavelength is employed as the source. The normalized transmittance for a linear, elliptical and circular polarization state of incident light with corresponding nonlinear refractive and nonlinear absorptive changes is studied. Intensity-dependent change in the refractive index (Δn) and change in the absorption coefficient (Δβ) with photoisomerization as well as two independent tensor components χxxyy3 and χxyyx3 of third order susceptibility (χ3) are reported. It is observed that nonresonant electronic nonlinearities dominate to give rise to an optical nonlinear response that can be exploited for use as optical switching. (paper)