Tamm plasmon Photonic Crystals : from Bandgap Engineering to Defect Cavity

We report for the first time the bandgap engineering of Tamm plasmon photonic crystals - Tamm plasmon structures of which the metalic layer is periodically patterned into lattice of subwavelength period. By adopting a double period design, we evidenced experimentally a complete photonic bandgap up to $150\,nm$ in the telecom range. Moreover, such design offers a great flexibility to tailor on-demand, and independently, the band-gap size from $30\,nm$ to $150\,nm$ and its spectral position within $50\,nm$. Finally, by implementing a defect cavity within the Tamm plasmon photonic crystal, an ultimate cavity of $1.6\mu m$ supporting a single highly confined Tamm mode is experimentally demonstrated. All experimental results are in perfect agreement with numerical calculations. Our results suggests the possibility to engineer novel band dispersion with surface modes of hybrid metalic/dielectric structures, thus open the way to Tamm plasmon towards applications in topological photonics, metamaterials and parity symmetry physics

Super Bound States in the Continuum on Photonic Flatbands: Concept, Experimental Realization, and Optical Trapping Demonstration

In this work, we theoretically propose and experimentally demonstrate the formation of a super bound state in a continuum (BIC) on a photonic crystal flat band. This unique state simultaneously exhibits an enhanced quality factor and near-zero group velocity across an extended region of the Brillouin zone. It is achieved at the topological transition when a symmetry-protected BIC pinned at $k=0$ merges with two Friedrich-Wintgen quasi-BICs, which arise from destructive interference between lossy photonic modes of opposite symmetries. As a proof-of-concept, we employ the super flat BIC to demonstrate three-dimensional optical trapping of individual particles. Our findings present a novel approach to engineering both the real and imaginary components of photonic states on a subwavelength scale for innovative optoelectronic devices

Reconfigurable Flat Optics with Programmable Reflection Amplitude Using Lithography-Free Phase-Change Materials Ultra Thin Films

We experimentally demonstrate a very large dynamic optical reflection modulation from a simple unpatterned layered stack of phase-change materials ultrathin films. Specifically, we theoretically and experimentally demonstrate that properly designed deeply subwavelength GeSbTe (GST) films on a metallic mirror produce a dynamic modulation of light in the near-infrared from very strong reflection (R>80%) to perfect absorption (A > 99,97%) by simply switching the crystalline state of the phase-change material. While the amplitude of modulation can lead to an optical contrast up to 10^6, we can also actively "write" intermediate levels of reflection in between extreme values, corresponding to partial crystallization of the GST layer. We further explore several layered system designs and provide guidelines to tailor the wavelength efficiency range, the angle of operation and the degree of crystallization leading to perfect absorption

Etude et réalisation d'un microscope de champ proche optique avec asservissement de type "shear force" (application à l'étude en champ proche du vieillissement de fibres optiques)

Dans le cadre d'utilisation des fibres optiques dans les réseaux FTTH (Fiber To The Home) et FTTB (Fiber To The Building), celles-ci subissent des contraintes et un environnement plus sévères que les fibres placées dans les réseaux actuels, c'est à dire les réseaux sous-marins et les réseaux enterrés. La fibre optique subit au cours du temps une modification de ses propriétés mécaniques, dûe à la diffusion d'eau à travers le revêtement polymère qui protège la fibre. Cette présence d'eau à l'interface silice-revêtement entraîne une modification de l'état de surface de la fibre optique. A cet effet dans ce travail de thèse nous avons développé un dispositif expérimental permettant l'étude à l'échelle nanométrique de la surface de silice des fibres optiques. Il s'agit d'un microscope de champ proche optique avec une régulation de type " shear force ". Cette technique fournit une information double, une information topographique et une information de nature optique. Dans un premier temps, nous présentons les notions concernant les propriétés mécaniques des fibres et les techniques de caractérisation s habituelles dans le domaine de la fiabilité. Ensuite, le dispositif de champ proche optique mis au point est détaillé, en particulier la partie concernant la boucle de rétroaction utilisant la force de cisaillement...DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

Plasmon-based tomographic microscopy

International audienc

High-resolution surface-plasmon imaging in air and in water: V(z) curve and operating conditions.

International audienc

Porous-silicon photonic crystals based on Bragg mirror for refractive index sensing

International audienceno abstrac

High-resolution surface-plasmon imaging in air and in water: V(z) curve and operating conditions

We present what are believed to be the first images obtained with a far-field high-resolution scanning surface-plasmon microscope in an aqueous medium. Measurements of V͑z͒, the output response of the microscope, versus defocus z give a signature of the surface-plasmon propagation. V͑z͒ is strongly conditioned by the laser beam diameter and the objective's numerical aperture, and we show how the operating mode (in air and in water) must be chosen to maximize the surface-plasmon field and to minimize diffraction (edge) effects. © 2007 Optical Society of America OCIS codes: 240.6680, 180.5810, 180.3170. Surface-plasmon polaritons (SPPs) are electromagnetic evanescent waves propagating at the interface of a conductive layer and a dielectric. The propagation condition of these surface waves is very sensitive to the metal-dielectric interface. These two properties are at the origin of the great success of SPPs in biosensor applications 1,2 known as surface-plasmon resonance. The surface-plasmon microscope (SPM) developed by Rothenhausler and Knoll 3 offered a subnanometer sensibility of adsorbed biological objects. Surface-plasmon resonance and SPM principles are both based on intensity measurements of reflected light by coupling SPP with a prism in a Kretschmann attenuated total reflection configuration. 4 SPM lateral resolution is limited by the SPP propagation length, which is of the order of a few micrometers. Actually, resolution and sensibility (i.e., contrast) evolve in opposite directions and are both related to the intrinsic SPP propagation length. 3,5 Microscopic techniques using SPP, such as scanning near-field optical microscopy 6 or a recent far-field technique 7 based on guided SPP coupling, provide improved resolution but are still hardly exploitable in aqueous media, which limits their biological application. Recently, Zhang and colleagues 8 have proposed a wide-field SPM with a solid immersion lens to work in liquid media. Better contrast and resolution can be achieved 9 with a scanning surface-plasmon microscope (SSPM) inspired by scanning acoustic microscopy techniques. 10 Resolution is first improved by localizing SPP with a large-numerical-aperture lens. Sensitivity is increased by SPP phase recording rather than intensity. Despite the nonintrusiveness of this method, to our knowledge its implementation in an aqueous environment has not been reported since the first measurements in air. Figure 1(a) shows the SSPM principle. 9,12 The excitation of SPPs is analogous to the Kretschmann configuration 4 : the coupling medium of refractive index n 0 is made from an objective lens (OL), immersion oil, and a coverslip. The coverslip is coated with a 45 nm layer of gold ͑n 1 ͒. The final dielectric medium with refractive index n 3 is air or water. The re