Yun Seon Do

Enhanced photoluminescence from zinc oxide by plasmonic resonance of reduced graphene oxide

We demonstrate 2.79- and 10.16-fold enhanced photoluminescence (PL) from band-edge and defect levels of zinc oxide (ZnO) using a plasmonic resonance of reduced graphene oxide (RGO) in the UV frequency range. RGO shows superior tunability on the light absorption of ZnO by the confined plasmonic resonance, which results in strong PL emission. We conclude that the absorption of ZnO in close proximity to the RGO layer can be enhanced. These arguments are strongly supported by different PL enhancements depending on the distance between RGO and ZnO layers, time-resolved PL, and numerical calculations.

Matching Surface Plasmon Modes in Symmetry-Broken Structures for Nanohole-Based Color Filter

Metallic nanoholes have been highlighted by their possible use as plasmonic color filters (PCFs). However, previous results have demonstrated the functions of the PCFs as stand-alone components and have provided few explanations about the optimization of these structures. We provide a design method of the PCFs that offers unique analytic insights about extraordinary optical transmission (EOT) in a systematic manner. The dielectric environment in the cylindrical hole has an important role to match the surface plasmon (SP) modes in holes and subsequently to enhance the EOT. Efficient EOT was achieved with finite dimensions less than the penetration depth of the SPs. This letter will provide more realistic guidelines for designing nanohole-based applications.

Quantitative analysis of enhancing extraordinary optical transmission affected by dielectric environment

We propose an effective way to mediate extraordinary optical transmission (EOT) in metallic hole array systems. The EOT phenomena are measured quantitatively by simple calculation which includes the effective values of the optical constants considering finite dimensions of the dielectric layer. The design of dielectric media along the metallic holes plays an important role in tuning the EOT by adjusting the amount of localized charge distribution around the holes. The consistent thickness of the dielectric media surrounding all metal surfaces consequently brings about the surface plasmon resonance at an energy level similar to that in a thin continuous film, and helps to enhance the EOT. The results provide a more plausible explanation to interpret the enhanced EOT mechanism, and will be helpful for designing metallic nano hole structures for use in practical applications with finite dimensions of the systems.

Spectral Tuning of Europium Complex by Competition Between Absorption and Scattering of Gold Nanoparticles

We demonstrate that localized surface plasmon resonance (SPR) supported by gold nanoparticles provides an additional method to control enhancement and quenching dynamics of the radiative transition from rare-earth-ion-doped optical materials. We show that localized plasmon resonance by gold nanoparticles can selectively enhance electric-dipole-like transitions of trivalent europium ion. Through numerical calculations by finite-difference time-domain method, we find that scattering among the interactions for the localized SPR provides enhancement on radiative transitions of trivalent europium ion. We believe these results can be utilized to help extract strong emission from luminescent materials by confined plasmon resonance on nanoscaled structures.

Plasmonic color filters for large area display devices fabricated by laser interference lithography

We demonstrated a plasmonic color filter adopting laser interference lithography technology. Nano scaled hole arrays were obtained with a regular spatial period through the whole glass substrate area of 2.5 cm × 2.5 cm.