Femtosecond and continuous wave nonlinear optical properties

Herein we report our experimental results on nonlinear optical properties of (H2)2SnPc (I) , Sn(OH)2Pc (II), and Sn(Cl)2Pc (III) studied using Z-scan technique with 800 nm, 100 fsec pulses, and 633 nm continuous wave (cw) laser excitation. Femtosecond open-aperture Z-scan data revealed these molecules exhibited strong 3PA coefficient (α3). The estimated values of α3 were ~4.0×10-5, ~2.0×10-5 cm3/GW2, and ~1.5×10-5 cm3/GW2 for I, II, and III respectively obtained after deducting the solvent contribution. Closed aperture data recorded with femtosecond pulses revealed positive nonlinearity for all the molecules. We also observed large nonlinear response in the cw regime at 633 nm. Closed aperture scans performed with 633 nm indicated strong negative nonlinearity while open aperture scans depicted mixed response. The performance of these alkyl phthalocyanines in various time domains vis-à-vis recently reported phthalocyanines is discussed in detail