Tailoring the optical properties at the micro- and nanoscale is key to enable new experiments in the field of quantum optics and biophotonics. To this end, I use my strong background in numerical simulations as well as nano- and microfabrication techniques together with the expertise in spectroscopy, linear and nonlinear optics to enable and conduct experiments.
Dark-field microscopy is a background-free imaging method that provides high sensitivity and a large signal-to-noise ratio. It finds application in nanoscale detection, biophysics and biosensing, particle tracking, single molecule spectroscopy, X-ray imaging, and failure analysis of materials. In dark-field microscopy, the unscattered light path is typically excluded from the angular range of signal detection. This restriction reduces the numerical aperture and affects the resolution. Here we introduce a nonlinear dark-field scheme that overcomes this restriction. Two laser beams of frequencies w1 and w2 are used to illuminate a sample surface and to generate a purely evanescent field at the four-wave mixing (4WM) frequency w4wm = 2w1 − w2. The evanescent 4WM field scatters at sample features and generates radiation that is detected by standard far-field optics. This nonlinear dark-field scheme works with samples of any material and is compatible with applications ranging from biological imaging to failure analysis.
Extraordinary All-Dielectric Light Enhancement over Large Volumes
Rebecca Sainidou,
Jan Renger,
Tatiana V. Teperik,
María U. González,
Romain Quidant,
F. Javier García de Abajo
We present resonant dielectric structures exhibiting arbitrarily large optical field enhancement, only limited by fabrication imperfections. Three different arrangements are investigated, based upon dielectric waveguides, dielectric particle arrays, and a combination of these two structures. Experimental confirmation of enhancement in a waveguide resonator is achieved by measuring the luminescence of quantum dots dispersed in the hot optical region of the structure. The performance of these systems can be readily controlled by simply changing geometrical parameters, which allows obtaining remarkable values of the intensity enhancement approaching 10^5 relative to the incident intensity over large volumes under feasible experimental conditions. This opens new avenues for all-optical switching and biosensing.
Fiber-Coupled Surface Plasmon Polariton Excitation in Imprinted Dielectric-Loaded Waveguides
Andreas Seidel,
Jacek Gosciniak,
Maria U. Gonzalez,
Jan Renger,
Carsten Reinhardt,
Roman Kiyan,
Romain Quidant,
Sergey I. Bozhevolnyi,
Boris N. Chichkov
International Journal of Optics
2010
1-6
(2010)
| Journal
We present fiber-coupled dielectric-loaded plasmonic waveguides for 1.55 μm telecom wavelength fabricated by two-photon polymerization and nanoimprint lithography. The waveguide structures include 100-μm-long plasmonic waveguides connected on both ends to tapered dielectric waveguides used for end-fire coupling with optical fibers. The excitation of plasmonic waveguides is verified via polarization-resolved measurements of the overall transmission, demonstrating thereby that this technology is suitable in principle for the integration of plasmonic components into fiberoptics. Loss mechanisms are investigated and improvements suggested to reduce transmission losses and consequently increase the viability of practical application.
Hidden progress: broadband plasmonic invisibility
Jan Renger,
Muamer Kadic,
Guillaume Dupont,
Srdjan S. Aćimović,
Sébastien Guenneau,
Romain Quidant,
Stefan Enoch
One of the key challenges in current research into electromagnetic cloaking is to achieve invisibility at optical frequencies and over an extended bandwidth. There has been significant progress towards this using the idea of cloaking by sweeping under the carpet of Li and Pendry. Here, we show that we can harness surface plasmon polaritons at a metal surface structured with a dielectric material to obtain a unique control of their propagation. We exploit this control to demonstrate both theoretically and experimentally cloaking over an unprecedented bandwidth (650–900 nm). Our non-resonant plasmonic metamaterial is designed using transformational optics extended to plasmonics and allows a curved reflector to mimic a flat mirror. Our theoretical predictions are validated by experiments mapping the surface light intensity at a wavelength of 800 nm.
Design and properties of dielectric surface plasmon Bragg mirrors
Sukanya Randhawa,
María Ujué González,
Jan Renger,
Stefan Enoch,
Romain Quidant
The ability of gratings made of dielectric ridges placed on top of flat metal layers to open gaps in the dispersion relation of surface plasmon polaritons (SPPs) is studied, both experimentally and theoretically. The gap position can be approximately predicted by the same relation as for standard optical Bragg stacks. The properties of the gap as a function of the grating parameters is numerically analyzed by using the Fourier modal method, and the presence of the gap is experimentally confirmed by leakage radiation microscopy. We also explore the performance of these dielectric gratings as SPP Bragg mirrors. The results show very good reflecting properties of these mirrors for a propagating SPP whose wavelength is inside the gap.
Surface-Enhanced Nonlinear Four-Wave Mixing
Jan Renger,
Romain Quidant,
Niek van Hulst,
Lukas Novotny
We report on a particularly strong third-order nonlinear response from nanostructured gold surfaces. Two incident laser beams with frequencies w1 and w2 give rise to four-wave mixing (4WM) fields with frequencies 2w1 − w2 and 2w2 − w1. We demonstrate that the nonlinear response can be purely evanescent and that nanostructured surfaces convert the evanescent energy into propagating radiation, thereby increasing the efficiency of frequency conversion. The emitted 4WM radiation is found to be directional, polarized, coherent, and both frequency and angle tunable. The ability to perform efficient frequency conversion in reduced dimensions provides new opportunities for nanophotonics and active plasmonics.
