[Show abstract][Hide abstract] ABSTRACT: This work presents the fabrication of on-chip polychromatic light source from a colloidal suspension. Capillary force assembly of the colloidal mixture composed from red, blue and green fluorescent dye doped 100nm particles is performed on a patterned substrate to create particles structure composed of ~10,000 nanoparticles with a natural hexagonal close-packed arrangement. Under UV excitation, the particle structure exhibit a white light emission closed to the CIE characteristics of the ideal pure white.
[Show abstract][Hide abstract] ABSTRACT: Particles manipulation with optical forces is known as optical tweezing. While tweezing in free space with laser beams was established in the 1980s, integrating the optical tweezers on a chip is a challenging task. Recent experiments with plasmonic nanoantennas, microring resonators, and photonic crystal nanocavities have demonstrated optical trapping. However, the optical field of a tweezer made of a single microscopic resonator cannot be shaped. So far, this prevents from optically driven micromanipulations. Here we propose an alternative approach where the shape of the optical trap can be tuned by the wavelength in coupled nanobeam cavities. Using these shapeable tweezers, we present micromanipulation of polystyrene microspheres trapped on a silicon chip. These results show that coupled nanobeam cavities are versatile building blocks for optical near-field engineering. They open the way to much complex integrated tweezers using networks of coupled nanobeam cavities for particles or bio-objects manipulation at a larger scale.
[Show abstract][Hide abstract] ABSTRACT: In this paper, we study the influence of fabrication uncertainties on silicon-on-insulator optical nanosystems performances. The considered structure consists in near-field coupled twin nanobeam cavities. We have performed experiments on a given population of samples, and noticeable changes in light propagation and localization were observed. Thanks to an analytic coupled-mode-based method supported by three-dimensional numerical computations, we quantitatively explain these experimental observations. We have indeed noticed that a few percent variation of the system nominal dimensions is enough to significantly change the optical coupling conditions between the cavities. Particularly, we show that, under specific conditions, light can stay locked in one of the two cavities. This result highlights the issues of reproducibility and reliability concerning future industrial application, like nano-optical electromechanical systems.
[Show abstract][Hide abstract] ABSTRACT: In this work, we report the auto-assembly experiments of micrometer sized particles by optical trapping in the evanescent field of a photonic crystal nanocavity. The nanocavity is inserted inside an optofluidic cell designed to enable the real time control of the nanoresonator transmittance as well as the real time visualization of the particles motion in the vicinity of the nanocavity. It is demonstrated that the optical trap above the cavity enables the assembly of multiple particles in respect of different stable conformations.
[Show abstract][Hide abstract] ABSTRACT: We have fabricated a multislotted optical nanoresonator with several spatial field distributions which are all addressable by the wavelength. The reported structure consists in an array of evanescently coupled single mode photonic crystal nanocavities. By using a scanning near-field optical microscope, we quantify the morphology of the different optical mode volumes and show that they consist in grids of light confined at the subwavelength scaleOver the last recent years, optical microcavities have proven their ability to slow down, control and even trap light inside an ultra small volume. Several approaches have led to quality factor (Q) records allowing to reach high photon life-time for optical information processing. Optical nanocavities are also very efficient sensors for biological or chemical detection inside ultra small volumes. In such applications, the detection mechanism is based on a small change of the resonance wavelength due to the modification of the cavity optical near-field. In order to improve the sensing efficiency of such systems, it has also been proposed to fabricate air-slotted nanocavities in which the field is confined in an air sub-wavelength volume. In this configuration, the overlap between the cavity optical near-field and the analyze can be greatly improved.
General Assembly and Scientific Symposium, 2011 XXXth URSI; 09/2011
[Show abstract][Hide abstract] ABSTRACT: We report here an experimental observation of an extraordinary near-field interaction between a local probe and a small-volume solid-state nanocavity. We directly compare the normally observed near-field interaction regime driven by the perturbation theory and then report the extraordinary interaction regime. Subsequently, we show that the cavity can take up to 2 min to recover from this interaction after removing the probe and that leads to an extraordinary blue-shift of the cavity resonance wavelength (∼15 nm) which depends on the probe motion above the cavity and not the position. The reasons for this effect are not fully understood yet but we try to give some explanations
Photonics and Nanostructures - Fundamentals and Applications 07/2011; 9(3):269-275. · 1.79 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Twinned high Q nanobeam cavities can be optically coupled while being placed in the optical near-field of each other. They form then a new optical system which supports discrete field maps addressable by wavelength selection.
[Show abstract][Hide abstract] ABSTRACT: We propose a method to experimentally determine the Clausius–Mossotti factors and surface capacitances of colloidal particles. This two-step method is based on the following: (i) a precise positioning of particles on activated electrodes according to the applied frequency of an electric field and (ii) particles velocities measurements from a pure dielectrophoretic regime to build the Clausius–Mossotti factor. It confirms previous literature methods and measures the surface capacitance values for a wide range of particles such as polystyrene, silica, and gold whose diameters are at least 200 nm.
[Show abstract][Hide abstract] ABSTRACT: In this letter, we fabricate a multislotted optical nanoresonator with several spatial field distributions which are all addressable by the wavelength. The reported structure consists in an array of evanescently coupled single mode photonic crystal nanocavities. By using a scanning near-field optical microscope, we quantify the morphology of the different optical mode volumes and show that they consist in grids of light confined at the subwavelength scale.
[Show abstract][Hide abstract] ABSTRACT: The influence of a near-field tip on the spectral characteristics of a resonant mode of an active photonic crystal micro-cavity was investigated. The wavelength shift of the mode was theoretically and experimentally demonstrated and evaluated as a function of the nature and the position of the tip above the cavity. Experiment showed that the shift induced is ten times higher with a Si-coated silica probe than with a bare silica tip: a shift until 2 nm was reached with Si-coated tip whereas the shift with bare silica tip is in the range of the tenth of nanometer, for wavelengths around 1,55 microm.
[Show abstract][Hide abstract] ABSTRACT: We study here the lateral evanescent coupling between photonic crystals cavities. The structure consists in two identical monomode Fabry-Perot nanocavities, integrated on silicon-on-insulator slot-waveguides (WG). Spectral and optical near field measurements were led and supported quantitatively by three dimensional simulations. It appears that this system produces a bimodal response: two resonances corresponding, respectively, to an even and odd mode. Particularly, the even case exhibits a field localization in the air slot inferior to lambdaair/10. We demonstrate that merging a slotted WG structure with state-of-the-art nanocavities is a significant step toward an efficient air-slotted resonator.
[Show abstract][Hide abstract] ABSTRACT: We report the fabrication process of ultrahigh-Q toroidal microcavities (10–50 μm diameter) and integration of erbium-doped silicon-rich oxide thin film inside these structures. The microcavities are studied by micro-photoluminescence and show the presence of whispering gallery modes at room temperature. Quality factors as high as 3000 are measured, limited by the setup resolution.
Physica E Low-dimensional Systems and Nanostructures 05/2009; · 1.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Silicon-on-insulator slot waveguides are studied by scanning near-field optical microscopy. Images of the standing wave pattern were established experimentally and compared with numerical simulations. Fourier analysis along the propagation direction reveals noticeable frequencies both on the experiment and the computation that could be related not only to the guided mode but also to beating phenomena between the coupled waveguides. Finally, light confinement above the slot is directly visualized with a subwavelength resolution and is compared with the expected field distribution.
[Show abstract][Hide abstract] ABSTRACT: PC-based microcavity can present a large quality factor (Q) while preserving a small modal volume (V), thus enabling the high Q/V ratio required for studying cavity quantum electrodynamics at the single source level. To analyze the coupling between the sources and the cavity, one must observe directly and locally the field distribution inside the cavity. Because of the small size of such a cavity, far-field techniques, which are usually diffraction-limited, fail to achieve the needed resolution. In the present work, we emphasize the influence of the probe on NSOM measurement of PC-cavity modes. The intensity near-field map showed that the coupling seems to be done preferentially along the direction of the long axis of the tip. We compared the experimental cartography to the computed intensity of the field component parallel to the long axis and showed that the agreement between them was correct.
[Show abstract][Hide abstract] ABSTRACT: The fabrication process of Ultrahigh-Q toroidal microcavities and integration of erbium-doped silicon-rich oxide thin film inside these structures are reported. Using micro-photoluminescence setup, we achieve selective detection of whispering gallery modes at room temperature. Quality factors as high as 3200 are measured, limited by the setup resolution.
[Show abstract][Hide abstract] ABSTRACT: Near-field probe was used to tune the resonance wavelength of a linear cavity. Theorical and experimental study are presented to show the effect of the probe material on the cavity resonance.
[Show abstract][Hide abstract] ABSTRACT: The optical near field of a high-Q and ultrasmall volume photonic crystal nanocavity is visualized with a subwavelength resolution by using a scanning near-field optical microscope (SNOM) operating at the same time in collection-scanning mode and in interaction-scanning mode. It is shown that the nanocavity resonant mode is selectively visualized by using the SNOM interaction-scanning mode while the whole electromagnetic field surrounding the nanocavity is probed using the SNOM collection-scanning mode. The different optical near-field images are compared in light of a three-dimensional numerical analysis and we demonstrate an unexpected mode coupling at the cavity resonance.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate here that switching and tuning of a nanocavity resonance can be achieved by approaching a sub-micrometer tip inside its evanescent near-field. The resonance energy is tuned over a wide spectral range (Deltalambda/lambda~10(-3)) without significant deterioration of the cavity peak-transmittance and of the resonance linewidth. Such a result is achieved by taking benefits from a weak tip-cavity interaction regime in which the tip behaves as a pure optical path length modulator.
[Show abstract][Hide abstract] ABSTRACT: While optical near-field microscopy techniques have been devoted to mapping the electromagnetic fields down to the Raleigh limit, an exciting challenge is now to use near-field probes to manipulate in situ the properties of these electromagnetic fields. Here we report the resonance tuning and therefore switching of an ultra-low volume (V≈0.6(λ/n)3) solid state resonator by evanescent interaction with a nanometric dielectric tip. By modelling the tip-nanocavity interaction, we demonstrate that a lossless interaction regime can be achieved in which the tip behaves as a pure optical path length modulator. To cite this article: B. Cluzel et al., C. R. Physique 9 (2008).