Multiphoton absorbing materials: Molecular designs, characterizations, and applications

There has been a significant progress in the past decade in the study of multiphoton absorbing materials, such as the design and synthesis of two-photon absorbing materials with a very large cross section. Although it is still possible to further enhance the molecular 2PA cross section value by using an optimized molecular design strategy, for certain applications the two-photon-property requirement has basically been met with the new available materials. As such, there have been research on the major applications of multiphoton excitation (MPE) and multiphoton active materials. One of them, multiphoton pumped lasing have been used to achieve tunable frequency up-conversion of coherent light without the phase-matching requirement. It has the advantage of negligible initial attenuation for a strong signal. As such, it can be utilized for protection of optical sensors or human eyes from laser radiation-induced damage.