ABSTRACT
Abstract This chapter introduces basic mechanism of two-photon absorption (2PA) and its unique feature of spatial resolution with near-infrared (NIR) excitation. Principles of designing materials to exhibit large two-photon absorptivities are explained. Difference in excitation selection rule between one-photon and two-photon excitation (2PE) for these materials is discussed. Potential applications for 2PA, such as three-dimensional (3D) data storage, fl uorescent imaging, 3D microfabrication, photodynamic therapy (PDT) and optical power limiting are briefl y described. Requirements of material optimization for the particular applications are also discussed. The chapter concludes with a brief introduction of future challenges.
