Ultrafast broadband optical limiting in simple pyrene-based molecules with high transmittance from visible to infrared regions

Pyrene is considered as one of the most promising nonlinear functional building blocks. The nonlinear optical properties of materials can be improved by modifying the main nonlinear group possession ratio occupied in frontier molecular orbitals. Accordingly, we designed and synthesized two isomeric molecules based on pyrene for ultrafast broadband optical limiters. Different pyrene possession ratios occupied in frontier molecular orbitals were calculated through quantum chemical methods between two molecules. The higher average pyrene possession ratio occupied in frontier molecular orbitals exhibited better nonlinear properties in such structures, which was consistent with the experimental data. Excellent optical limiting behaviors were observed under femtosecond laser excitations at multiple wavelengths (range from 515 to 900 nm), which resulted from two-photon absorption (TPA) and TPA induced excited-state absorption (ESA). Moreover, the sample exhibited extremely high transmittance (>91%) from visible to infrared regions (500 to 900 nm). Our results show that pyrene-based derivatives can be considered as promising candidates for broadband ultrafast optical limiters.