OPTIMIZING NANO-OPTICAL ANTENNA FOR THE ENHANCEMENT OF SPONTANEOUS EMISSION

We study the characteristics of nano-optical antenna made of two gold nano-particles by three dimensional numerical calculations in visible and near infrared bands. To carry the computational burden and guarantee the precision and speed of a three dimensional FDTD calculation, adaptive mesh reflnement technology is used. In this paper, we flrst highlight the concrete way of controlling the emitter position and orientation to fulflll the requirements of larger spontaneous emission enhancement. Then, we analyze the far fleld distribution and flnd that the far fleld directivity is strongly in∞uenced by surface plasmon polaritons (SPPs). Choosing the incident wavelength of 600nm, we compute the decay rates and radiant e-ciency as a function of antenna geometry limitations. Next, the particle aspect ratio is optimized, and we obtain that L=R = 4 is the best for our optical-antenna. Furthermore, we present a spectrum analysis. Around 5000 fold spontaneous emission enhancement is successfully achieved. Finally, we flnd a piecewise linearity relationship between the particle length and resonant wavelength.