Lasing mechanism found in water droplets

Tiny molecular forces at the surface of water droplets can play a big role in laser output emissions. As the most fundamental matrix of life, water drives numerous essential biological activities, through interactions with biomolecules and organisms. Studying the mechanical effects of water-involved interactions contributes to the understanding of biochemical processes. According to Yu-Cheng Chen, professor of electronic engineering at Nanyang Technological University (NTU), "As water interacts with a surface, the hydrophobicity at the bio-interface mainly determines the mechanical equilibrium of the water. Molecular hydrophobicity at the interface can serve as the basis for monitoring subtle biomolecular interactions and dynamics."

Water droplets have been used to form biological microlasers that exploit water's intrinsic ability to confine light with minimal scattering. Droplet lasers benefit from laser oscillation in a microcavity, so any subtle changes induced by the gain medium or cavity can be amplified, leading to dramatic changes of laser emission characteristics. While droplet lasers have become cutting-edge platforms in biochemical/physical studies and biomedical applications, the optical interaction between droplet resonators and an interface has remained unknown.