Purcell gain equalized zero-mode waveguide.

We refresh the design of zero-mode waveguides (ZMWs) by introducing metamaterials that makes the zeroth order resonant mode existence. Of particular importance, the resulting electromagnetic field exhibits nearly constant distribution but not a trivial solution of Maxwell's equation, showing great advantage to equalize the excitation rate of molecules throughout the waveguides. A closed form expression for the wave impedance is derived which is verified by the finite-difference time-domain simulations. Benefitted from the cavity Purcell effect which is lacking in existing ZMWs, fluorescence amplification and lifetime reduction are simultaneously enhanced. A practical design where the excitation volume reduced down to sub-zeptoliter and the fluorescence lifetime shortened to picosecond scale is illustrated. This result makes single molecule real time (SMRT) sensing of biochemical reactions at biophysically relevant concentrations (~ µM) possible, combining off-the-shelf ultrafast lasers.

Label-free multi-color superlocalization of plasmonic emission within metallic nano-interstice using femtosecond chirp-manipulated four wave mixing.

We demonstrate an as yet unused method to sieve, localize, and steer plasmonic hot spot within metallic nano-interstices close to percolation threshold. Multicolor superlocalization of plasmon mode within 60 nm was constantly achieved by chirp-manipulated superresolved four wave mixing (FWM) images. Since the percolated film is strongly plasmonic active and structurally multiscale invariant, the present method provides orders of magnitude enhanced light localization within single metallic nano-interstice, and can be universally applied to any region of the random film. The result, verified by the maximum likelihood estimation (MLE) and deconvolution stochastic optical reconstruction microscopy (deconSTORM) algorithm, may contribute to label-free multiplex superlocalized spectroscopy of single molecule and sub-cellular activity monitoring combining hot spot steering capability.

The contribution of nonlocal electro-opto-thermal interaction to single molecule nonlinear Raman enhancement.

we develop a precise modelling where nonlocal electro-opto-thermal interactions are comprehensively included for the analysis of nonlinear Raman enhancement and plasmonic heating. An interaction enhancement factor G(IEF) is introduced to quantify the coupling between the electromagnetic field and the temperature field which is rarely considered in the estimation of Raman enhancement. For the case of isolated single nanosphere, G(IEF) can be up to ten, indicating a thermal origin which well explains the observed temperature rise, shortened blinking period, and the nonlinearly enhanced Raman cross-section. For the case of nanodimer, the suppression of plasmon heating was analyzed, demonstrating the great capability to mitigate biomolecular degradation and blinking.

Orders of magnitude enhancement of mode splitting by plasmonic intracavity resonance.

we report on significant mode splitting in plasmonic resonators induced by intracavity resonance. In contrast to traditional dielectric resonators where only picometer range of splitting was achieved, splitting over several hundred nanometers can be obtained without using ultrahigh quality resonators. We show that by appropriately choosing the coupling length, minute reflection is sufficient to establish intracavity resonance, which effectively lifts the degeneracy of the counterpropagating modes in the resonator. The mode splitting provides two self-referenced channels enabling simultaneous monitoring of the position and the polarizability of nano-scatterers in the resonator.

Giant angular dispersion mediated by plasmonic modal competition.

We report on the modal competition mediated angular dispersion by heterogeneously coupled plasmonic waveguides. By varying the wavelength of the excitation, the surface waves propagate alongside the upper and lower interfaces can be manipulated in coupled, decoupled, and cutoff regimes. Depending on the coupling states, the output beam can be steered between +15° and -17° for wavelength from λ = 695 nm to λ = 675 nm. The maximum achieved angular dispersion can be as large as 2.1°/nm. This finding may revolutionize current design concept of spectrometers, providing a significant way to scale down the form factor further into nano-size.