Third-Order Optical Nonlinearity in Novel Porphyrin Dimers

We investigate the third-order optical nonlinearities in four novel porphyrin dimers (dimers A to D) and a monomeric porphyrin H₂ CPTPP measured by using the single-beam z-scan technique with a pulsed Q-switched Nd:YAG nanosecond laser at 532nm. All the samples show strong excited state absorption (ESA) and high value of χ⁽³⁾ in the ns domain at this wavelength. We perform a comparison between dimer A and its monomer H₂ CPTPP in their third-order optical nonlinearity, and discuss the relationships between the values of χ⁽³⁾ and the different bridging groups for all the dimers.