Imaging of Surface Plasmon Polaritons with Up-Conversion Fluorescent Microscopy

Lam Yen Thi Nguyen^1*, Yi-Hsin Lee¹, Yu-Fang Chang¹, Jiun-Yuan Lin¹, Hung-Chih Kan¹

¹Department of Physics, National Chung Cheng University, Chiayi, Taiwan

* Presenter:Lam Yen Thi Nguyen, email:thinguyen3108@gmail.com

Imaging and characterization surface plasmon polaritons (SPPs) are important for the investigations of the designing of plasmonic circuits for the desired applications. In this study, a method to direct imaging of SPPs propagation on metal film with up-conversion fluorescent images was reported. The up-conversion fluorescence was obtained with rare-earth ion, such as Er3+, Yb3+, and Nd3+ doped nanoparticles deposited on the sample surface. We observed the detailed structure of SPPs wave fronts that resulted from interference between the incident light and the SPPs excited on the surface by taking the ratio image obtained with fluorescent emission at different wavelengths. We further demonstrate the evolution of the SPPs wave fronts due to the refraction of SPPs when propagating across a boundary of regions of different effective refractive indices. We carried out theoretical derivations of the equations for solving the SPPs wavelengths according to the electromagnetic boundary conditions and obtained the solution numerically. We also performed numerical simulations of SPPs propagation on the sample to reproduce the experiment. We obtained qualitative agreement between the simulation and the experiment.

Keywords: Surface plasmon polaritons, UCNPs fluorescent microscopy, Ratio of fluorescent image.