Optical Physics Lab (Wen group) is a multidisciplinary research team at Institute of Physics, Academia Sinica, Taiwan. We developed advanced nonlinear/ultrafast optical spectroscopic techniques, aiming to elucidate the light-matter interactions at interfaces and novel quantum materials. We particularly focus on physical chemistry phenomena at liquid water surfaces – the most important platform for chemical and biological processes. We probe vibrations of the interfacial molecules selectively by nonlinear optical means, offering the unique opportunity to establish the structure-property-function relation of the water interfaces on the molecular level. We are also interested in nonlinear optics of quantum materials, particularly the effect of quantum geometry of the band structure on the nonlinear photocurrent generation. The study promotes the development of next-generation optoelectronic and solar-energy applications.