Extremely small group velocity realized with surface plasmon polaritons in metallic photonic crystals

Summary form only given. The small group velocity of radiational eigenmodes that are often realized in photonic crystals leads to the enhancement of various optical and quantum optical phenomena, since the effective interaction constant between the radiation field and the matter system is inversely proportional to the group velocity. In this paper, we will show that the dispersion relation of metallic photonic crystals, which is difficult to estimate by the conventional plane-wave expansion method, can be calculated accurately by the numerical simulation of dipole radiation based on the finite-difference time-domain method, and that extremely small group velocities are realized by surface plasmon polaritons.