Selective Plasmonic Enhancement of Electric- and Magnetic-Dipole Radiations of Er Ions

作者：Choi Bongseok; Iwanaga Masanobu^*; Sugimoto Yoshimasa; Sakoda Kazuaki; Miyazaki Hideki T

来源：Nano Letters, 2016, 16(8): 5191-5196.

DOI：10.1021/acs.nanolett.6b02200

• Plasmon enhancement
• electric dipole
• magnetic dipole
• Er ions
• LDOS optimization
• plasmon nanocavity

Lanthanoid series are unique in atomic elements. One reason is because they have 4f electronic states forbidding electric-dipole (ED) transitions in vacuum and another reason is because they are very useful in current-day optical technologies such as lasers and fiber-based telecommunications. Trivalent Er ions are well-known as a key atomic element supporting 1.5 mu m band optical technologies and also as complex photoluminescence (PL) band deeply mixing ED and magnetic-dipole (MD) transitions. Here we show large and selective enhancement of ED and MD radiations up to 83- and 26-fold for a reference bulk state, respectively, in experiments employing plasmonic nanocavity arrays. We achieved the marked PL enhancement by use of an optimal design for electromagnetic (EM) local density of states (LDOS) and by Er-ion doping in deep subwavelength precision. We moreover clarify the quantitative contribution of ED and MD radiations to the PL band, and the magnetic Purcell effect in the PL-decay temporal measurement. This study experimentally demonstrates a new scheme of EM-LDOS engineering in plasmon-enhanced photonics, which will be a key technique to develop loss-compensated and active plasmonic devices.

• 出版日期2016-8