Abstract
Plasma resonance in metals exhibits some unique optical phenomena that occur on the surface of metal with nanostructures. The use of surface plasmons has been proposed in various fields, such as nanometer-resolution near-field optical microscopy, nanoscale optical circuits, single-molecule detection, molecular sensors, cancer treatment, solar cells, lasers, and holography. The study of plasma resonance is called "plasmonics" and is expected as a new field of nanophotonics. In this report, I review the principles and limits of plasmonics and give a future outlook.