1:30pm - 2:00pmInvited
Heterogeneous Nanoplasmonics for Quantum Optics and Biosensing
ICFO - The Institute of Photonic Sciences, Spain
Extensive research in Nano-optics over the last decade has made possible controlling optical fields on the nanometer scale. The concentration of light, well below the limit of diffraction, opens plenty of new opportunities towards enhanced interaction with tiny amounts of matter down to the single molecule/atom level. In this talk we will present our recent advances in enhanced light-matter interaction on the nanometer scale and their applications to both quantum optics and biosensing.
The first part of the talk focuses on the controlled interaction of single quantum emitters with optical nanostructures. We first discuss different strategies to deliver a single quantum emitter in the hot spot of a plasmonic nanostructure. Next we show how these techniques are applied to deterministically locate single nano-diamonds in the hot spot of plasmonic antennas and waveguides. In particular, we discuss the possibility to build on-chip single photon sources as well as nanolasers.
In the second part of the talk, we change gear and present our latest advances in the optical, label free detection of biomarkers based on both gold and silicon nanoantennas integrated into a state-of-the-art microfluidic platform. We first demonstrate the capability of our platform to detect low concentrations (<1ng/ml) of protein cancer markers in human serum with low unspecific binding and high repeatability. In a second step we present a novel design that enables to simultaneously determine the absolute concentration of four different target molecules from an unknown sample. The system is validated in the context of breast cancer, as a strategy to assess the risk for brain metastasis. Our research demonstrates the high potential of optical nanoresonators for the detection of different biomarkers in real biological samples and thus gets us closer to future nano-optical point-of-care devices.
2:00pm - 2:30pmInvited
Accelerating Spontaneous Emission with Metamaterials
1King's College London, United Kingdom; 2Tel Aviv University, Israel; 3University of Massachusetts Lowell, United States
Controlling spontaneous emission rate of fluorescent emitters via the design of nanostructured materials with appropriate electromagnetic properties is important for the development of many applications ranging from biosensing and imaging to quantum information processing. In particular, the nanostructures capable of modifying emission rate which are directly intergratable in photonic waveguides and with a broadband response are of particular advantage. We will discuss the modification of the emission rate of emitters embedded inside a hyperbolic metamaterial waveguide and show, both experimentally and theoretically, that the mode structure modified by nonlocal properties of such metamaterials can provide unprecedentedly strong reduction of an emitter lifetime. Spontaneous emission of quantum dots embedded inside multilayered nanoparticles as well fluorescence resonant energy transfer in a hyperbolic metamaterial environment will also be discussed.
2:30pm - 2:45pmOral
Directional Fluorescence Enhancement by High-refractive Index Dielectric Nanoantenna
Data Storage Institute, Agency for Science, Technology and Research (A*STAR), Singapore
Optical nanoantennas have been extensively studied for manipulating luminescence of localized light sources (such as fluorophores, dyes, quantum dots etc.) in visible and IR spectral ranges. Owing to the resonant nature of plasmonic elements plasmonic nanoantennas can create high near-field enhancement localized around the nanoantenna and enhance far-field luminescence. However, due to the strong losses of plasmonic materials in optical spectrum most of the energy tends to dissipate heating the nanoantenna and its surroundings which is often undesirable in biological applications.
Recently resonant high-refractive index dielectric nanostructures have been widely investigated. Similar to plasmonic elements, they may possess strong resonances at optical frequencies. In contrast to plasmonics though, these resonances are associated only with displacement (polarization) currents and thus no Ohmic losses are involved.
In this paper, we present novel design concepts for nanoantennas based on resonant high-refractive index (n>2) dielectric nanostructures for boosting fluorescence enhancement into the direction perpendicular to the nanoantenna substrate. This signal enhancement direction corresponds to the position of a detector in conventional biodetection and bioimaging systems and thus is beneficial for increasing the detected fluorescence signal. The concepts are based on introduction of reflectors consisting either of larger nanoparticles or ridges and rotating the radiation pattern towards the required direction. The directional nanoantenna emission pattern is shown in simulations by surrounding the designed silicon nanoantennas by random independent dipoles. The achieved emission directionality is verified experimentally by the back-focal plane imaging of emission of quantum dots surrounding the fabricated nanoantenna designs.
2:45pm - 3:00pmOral
Low-Loss Dielectric Nanoantennas for Surface-Enhanced Fluorescence Spectroscopy and Nonlinear Photonics
Imperial College London, United Kingdom
Dielectric nanoantennas have recently emerged as promising alternative candidates to plasmonic systems in the visible range.1,2 When excited above their bandgap energies, high-refractive-index dielectric nanostructures can highly concentrate electric and magnetic fields within subwavelength volumes while presenting ultra-low absorption compared to metals.3 In particular, by locally enhancing the incident light intensity, dielectric nanoantennas are expected not only to produce negligible heating, but also boost nonlinear phenomena and surface-enhanced spectroscopies, since their efficiencies increase with the excitation density.
In this presentation, GaP and Ge nanoantennas will be introduced as promising nanosystems for surface-enhanced fluorescence and second and third harmonic generation on the nanoscale at visible wavelengths.3-5 In addition, hybrid dielectric/metallic Si/Au nanoantennas will also be analyzed.6 Fluorescence enhancement factors of over 3000 and harmonic conversion efficiencies on the order of 10-3% will be demonstrated for this suitably engineered dielectric-based nanostructures.
1Albella, P.; Poyli, M. A.; Schmidt, M. K.; Maier, S. A.; Moreno, F.; Sáenz, J. J.; Aizpurua, J. J. Phys. Chem. C 2013, 117, 13573-13584.
2 Shorokhov, A. S.; Melik-Gaykazyan, E. V.; Smirnova, D. A.; Hopkins, B.; Chong, K. E.; Choi, D. Y.; Shcherbakov, M. R.; Miroshnichenko, A. E.; Neshev, D. N.; Fedyanin, A. A.; Kivshar, Y. S. Nano Lett. 2016, 16, 4857–4861.
3 Grinblat, G.; Li, Y.; Nielsen, M., Oulton R. F.; Maier S. A. Nano Lett. 2016, 16, 4635-4640.
4 Grinblat, G.; Li, Y.; Nielsen, M., Oulton R. F.; Maier S. A. ACS Nano 2017, 11, 953–960.
5 Cambiasso, J.; Grinblat, G.; Li, Yi.; Rakovich, A.; Cortés, E.; Maier, S. A. Nano Lett. 2017, 17, 1219–1225.
6 Shibanuma, T.; Grinblat, G.; Albella, P.; Maier S. A. Nano Lett. 2017, 17, 2647–2651.
3:00pm - 3:30pmInvited
Emission Rates and Light Propagation Through Correlated Disordered Dielectric Media
1Donostia International Physics Center, Spain; 2University of Fribourg, Switzerland; 3Institute of Microelectronics, Spanish National Research Council (CSIC), Spain
The statistics of emission rates in correlated disordered media is extremely sensitive to the details of the radial distribution function around the emitter. We analyze the emission statistics for a single emitter embedded in a finite cluster of resonant dielectric particles whose spatial locations are highly correlated. Multiple scattering and near-field effects on both lifetimes and transport statistics will be discussed in detail. As a particular interesting system we will consider the dynamic fluctuations of the emission rates assuming a standard Lennard-Jones-like (L-J) interaction between particles confined in a finite volume. This system is known to present a peculiar dynamic solid-liquid-like phase transition at finite temperature: Due to finite-size effects, the two phases cannot coexist at the melting temperature and the whole cluster presents an interesting dynamical behavior, switching between an amorphous solid-like phase and liquid-like phases. This makes it an ideal model system to analyze the effects of local order on the emission rates. In the solid phase at low temperatures, the equilibrium positions are close to those corresponding to a face-centred-cubic (FCC) lattice, and the spectrum of emission rates present a strong chromatic dispersion reminiscent of the band structure of an infinite crystal of resonant particles, including spectral windows where the emission is enhanced and pseudo-gaps where it is dramatically inhibited. At the melting temperature, the total scattering cross section of the system does not present significant differences between the two phases while the emission rate jumps following the dynamics of the system. While light scattering measurements would be blind to such dynamical changes, the lifetime statistics would then provide a direct signature of a phase switching behavior.
3:30pm - 3:45pmOral
Plasmonic Response of Superconducting Niobium in the Optical Spectral Range
1Optoelectronics Research Centre & Centre for Photonic Metamaterials, University of Southampton, United Kingdom; 2Department of Physics, National Taiwan University, Taiwan; 3Centre for Disruptive Photonic Technologies, The Photonics Institute, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore; 4School of Physics and Astronomy, University of Southampton, UK; 5Department of Physics, Loughborough University, United Kingdom; 6Research Center for Applied Sciences, Academia Sinica, Taiwan
We present the first experimental evidence of a direct link between the optical properties of a material and onset of superconductivity.
By measuring the dielectric constants of an unpatterned niobium film as well as the reflectivity of a nanostructured niobium metamaterial, we demonstrate a critical dependence of niobium optical response on temperature near its superconducting transition at 9K. In non-superconducting metamaterials, the temperature-related variations in the optical response tend to saturate below 50K. In contrast, we show that both the position and the strength of niobium metamaterial resonances exhibit a pronounced dependence on temperature down to a few Kelvin, with a sharp change in the behavior around the superconducting transition temperature at 9K. In addition, we also observed dramatic changes in the dielectric constant of unstructured niobium film around the superconducting transition temperature, measured in a separate experiment.
Our studies point to a hitherto unknown connection between superconductivity and optical range plasmonics. We explain the experimentally observed critical dependence of the metamaterial resonance position on the transition temperature of niobium by means of a thermodynamics-based model that takes into account the change in the free energy of the metamaterial resonator between the normal and superconducting states. We argue that this is a signature of the transition to the superconducting state, which is detected by infrared photons.