Third-Order Optical Nonlinearity of a 1,3-Bis(2,4,6-Trihydroxy-Phenyl)Squaraine

Abstract

The magnitude and dynamic response of the third-order optical nonlinearity of a 1,3-bis(2,4,6-trihydroxy-phenyl)squaraine was measured by femtosecond degenerate four-wave mixing (DFWM) technique at 800 nm. Ultrafast optical response has been observed and the magnitude of the second-order hyperpolarizability of the studied squaraine was measured as large as 3.8 ×10-31 esu. The large optical nonlinearities of the squaraine can be attributed to their rigid and intramolecular charge transfer structure, and the instantaneous NLO response of squaraine is mainly contributed from the electron delocalization.