Collecting each and every photon that a single molecule emits is a major goal in nanophotonic devices. To boost extraction efficiencies, the two mainstream strategies are on one hand plasmonics to enhance local field strengths and induce antenna effects, and on the other hand photonic crystals that aim to redirect light using strong dispersion at photonic band edges.
In a recent ACS Nano publication, we bridge the gap between these two opposite but complementary approaches and demonstrate a general strategy based on a plasmonic analog of photonic crystals. We show that already small plasmonic crystals patterned in gold film result in strong directionality of emission for molecules located in the structure.
This work pioneers the control of directionality by coherent coupling in finite antenna arrays driven by a single emitter. Moreover, it demonstrates that fluorescence radiation patterns can be designed at will by engineering surface plasmon Bloch modes. These results open a rich toolbox to engineer single photon emitters to emit selectively in particular angles, polarization states, or in more exotic beam proﬁles.
Optimizing the resonant properties of complex optical antennas is often a complex and time-consuming task. To ease the computational process and provide physical guidelines to the design optimization, we introduced in a publication in Physical Review A (highlighted as Rapid Publication) the so-called Weierstrass factorization theorem as a new tool in nanophotonics. We demonstrated that the scattering matrix can be decomposed exactly into a set of Lorentzian resonances over an arbitrary broad frequency range, and that the finding of these anomalies accurately determines all the scattering properties. This powerful approach does not require any fitting parameters and can take into account consistently an arbitrary number of modes. It can be applied to a broad range of cases, as we will show in forthcoming papers.