Localized photonic nanojets formed by core-shell diffraction gratings

摘要

The generations of localized photonic nanojets using core-shell diffraction gratings working in the visible light region are demonstrated numerically. The power flow patterns for the core-shell diffraction gratings are simulated by using the finite-difference time-domain method. The focusing qualities of localized photonic nanojets are evaluated in terms of focal length and transversal width along propagation and transversal directions. Due to surface plasmon polaritons, it has been demonstrated that the metallic shell is critical for power enhancement of photonic nanojet. The high-resolution imaging of the core-shell diffraction grating can be expected from the high-intensity photonic nanojet. The photonic nanojet could be operated in a wide range imaging for nano-scale targets through the core-shell diffraction grating.