Third-Order Nonlinear Optical Properties of Pseudoazulenes

The hyperpolarizabilities of several pseudoazulenes are evaluated using a semiempirical quantum chemistry package MOPAC-93 and compared with hyperpolarizabilities of simple molecules like chloroform, benzene, naphthalene and azulene. The third-order hyperpolarizability γ is measured for a derivative of 1,2-5,6 dibenzoxalene using a femtosecond Z-scan method at 800 nm. The resulting hyperpolarizability of 1.7×10-34 esu corroborates the theoretical prediction that pseudoazulene structures behave similar to other aromatic molecules provided the experiments are carried out in a non-resonant regime.