nl6b00853_si_001.pdf (2.19 MB)
Optically Thin Metallic Films for High-Radiative-Efficiency Plasmonics
journal contribution
posted on 2016-05-31, 00:00 authored by Yi Yang, Bo Zhen, Chia Wei Hsu, Owen D. Miller, John D. Joannopoulos, Marin SoljačićPlasmonics
enables deep-subwavelength concentration of light and has become important
for fundamental studies as well as real-life applications. Two major
existing platforms of plasmonics are metallic nanoparticles and metallic
films. Metallic nanoparticles allow efficient coupling to far field
radiation, yet their synthesis typically leads to poor material quality.
Metallic films offer substantially higher quality materials, but their
coupling to radiation is typically jeopardized due to the large momentum
mismatch with free space. Here, we propose and theoretically investigate
optically thin metallic films as an ideal platform for high-radiative-efficiency
plasmonics. For far-field scattering, adding a thin high-quality metallic
substrate enables a higher quality factor while maintaining the localization
and tunability that the nanoparticle provides. For near-field spontaneous
emission, a thin metallic substrate, of high quality or not, greatly
improves the field overlap between the emitter environment and propagating
surface plasmons, enabling high-Purcell (total enhancement >104), high-quantum-yield (>50%) spontaneous emission, even
as the gap size vanishes (3–5 nm). The enhancement has almost
spatially independent efficiency and does not suffer from quenching
effects that commonly exist in previous structures.