金屬奈米腔效應對量子點發光與福斯特共振能量轉移行為的數值模擬研究

Abstract

本研究利用數值模擬方法探討在金屬奈米孔洞和奈米管內偶極子的發光、福斯特共振能量轉移以及發光體的光色轉換行為。此外，我們也研究來自金屬奈米管下方代表量子井的偶極子到奈米管內發光體的福斯特共振能量轉移和光色轉換行為。結合腔體共振和表面電漿子耦合的效應，在腔體內當偶極子方向與金屬奈米孔洞軸平行時，可以觀察到輻射功率的頻譜尖峰。當偶極子方向垂直於孔洞軸時，輻射功率的頻譜峰變寬。由於能量施體在受體位置產生的電磁場強度和受體輻射功率隨波長變化劇烈，特定組合的施體和受體波長的福斯特共振能量轉移和光色轉換效率對金屬奈米孔洞或奈米管的幾何形狀非常敏感。如果能選擇適當的幾何形狀，光色轉換效率可以大幅提高。由於金的損耗較高，上述奈米尺度腔體效應在使用金製作的結構中與銀相比顯得較弱

The simulation studies on the behaviors of dipole emission, Förster resonance energy transfer (FRET) and color conversion of light emitters inside metal nano-holes and nano-tubes are performed. The FRET and color conversion behaviors from a quantum well (QW) dipole below a metal nano-tube into a light emitter inside the nano-tube are also numerically studied. Through the combined effects of cavity resonance and surface plasmon (SP) coupling, sharp peaks of radiated power can be observed when the dipole orientation is along the axis of a metal nano-hole. When the dipole orientation is perpendicular to the hole axis, the radiated power peaks become broad. Because of the strong spectral variations of the field intensities at the positions of the energy acceptors produced by the donors and the radiated powers of the acceptors, the FRET and color conversion efficiencies at a designated set of donor and acceptor wavelengths are sensitively dependent on the geometries of metal nano-holes or nano-tubes. The color conversion efficiency can be significantly enhanced if we choose the appropriate geometries. Compared with Ag, the nanoscale-cavity effects described above are weaker in those structures fabricated with Au because of its higher dissipation.