Photo-stability and Photo-damage of SPASER Nanoparticles under Nanosecond Pulsed-laser

SPASER nanoparticle (NP), with small size, ultranarrow spectral-line and good biocompatibility, is a potential biomedical nanoprobe. However, owning to the striking light absorption capacity of Au-resonator, huge energy could accumulate under strong pumping-laser, which would lead to poor photo-stability and unexpected photo-damage to SPASER NP, and is harmful to its future practical application but hasn't been systematically studied in experiment. In this paper, our experimental and theoretical researches revealed that the photo-stability of SPASER NP is largely determined by its structure parameters: smaller Au-core diameter, thicker silica-shell will contribute to better photo-stability. And the possibility and extent of photo-damage of SPASER NP depend on not only its intrinsic stability but also the external pumping-laser. Notably, the strong pumping condition for two-level SPASER system could lead to heating-melting-evaporation or even phase-explosion of SPASER NP, resulting in obvious photo-damage, while, the weak pumping condition for three-level SPASER system is quite friendly. This study provides reliable bases for the structural-properties optimization of SPASER NPs, which is of great significance for its future application as a novel luminescence probe.