BSWs are non-radiative electromagnetic waves confined at the interface between a truncated periodic dielectric multilayer and a surrounding media. As an alternative to SPPs (Surface Plasmon Polaritons), BSWs show dramatically enhanced propagation lengths up to several millimeters range and provide new optical opportunities such as the possibility to obtain TE or TM-polarized surface waves. They have found numerous applications in vapor sensing, biosensing, fluorescence detection and imaging, and integrated optics.
In this work, we propose a 1DPhC with a thin film of LiNbO3 (TFLN) as the top layer of the multilayer structure. The bonding of LiNbO3 into the 1DPhC structure brings anisotropy and nonlinear properties into the whole crystal allowing the tunability of the BSW devices.
Here we present 1DPhCs, which are able to sustain surface waves at the LiNbO3/air interface. Two different geometries have been studied, fabricated and optically characterized. The first one is based on the LiNbO3 membrane suspended in air and the second one is held by a stable glass platform.
The multilayer of the membrane based crystal is as following: air/6 pairs of Si3N4(200nm) and SiO2(215nm)/TFLN(1.1μm) – polished from bulk LN/air. The multilayer of the glass supported crystal is as following: glass/UV glue/6 pairs of Si3N4(220 nm) and SiO2(490nm)/TFLN(386nm)/air. 1DPhCs were characterized in Kretschmann configuration at visible and IR wavelengths.
Photonic crystal and plasmonic structures are the two main approaches used in nanophotonic for efficiently confining and enhancing the electromagnetic field at subwavelength scale. For these reasons, these two approaches have been both used for the optical trapping of nanometric particle. We present, here, experimental results showing that structures combining both photonic crystal and nanoantennas could lead to improved trapping performances.
In previous theoretical papers [1, 2] we have shown that when the critical coupling between a photonic crystal and a nanoantenna is reached, a large Gaussian beam could be efficiently coupled to a single nanoantenna. In this way, it is possible to generate a nanometric hotspot in the nanoantenna leading to a very efficient optical trap.
The experimental demonstration of this effect has been obtained on an SOI sample consisting in a gold nanoantenna located at the centre of a photonic crystal cavity. Stable trapping of 100 nm diameter nanoparticle has been observed using a 5mW laser at 1.31µm with a 5µm waist. The nanoparticle are trapped above the nanoantenna gap and a normalized trap stiffness of 0.3 fN.nm-1.mW-1 is measured. This result demonstrates the interest of this approach. We will discuss and compare it to the state of the art of nanotweezers.
 A. El Eter et al. Opt. Express 22, 14464 (2014).
 A. Belarouci et al. Opt. Express 18, A381 (2010).
Bloch surface waves (BSWs) are electromagnetic surface waves which can be excited at the interface between periodic dielectric multilayer and a surrounding medium. In comparison with surface plasmon polaritons these surface states perform high quality factor due to low loss characteristics of dielectric materials and can be exited both by TE and TM polarized light. A platform consisting of periodic stacks of alternative SiO2 and Si3N4 layers is designed and fabricated to work at the wavelength of 1.55 µm. The platform has an application in sensing and in integrated optics domain. A standard way of BSW excitation is coupling via Kretschmann configuration, but in this work we investigate a grating coupling of BSWs. Grating parameters are analytically and numerically optimized by RCWA and FDTD methods in order to obtain the best coupling conditions. The light is launched orthogonally to the surface of the photonic crystal and the grating. Due to a special grating configuration we demonstrate directionality of the BSW propagation depending on polarization of the incident light. The structure was experimentally realized on the surface of the photonic crystal by FIB milling. Experimental results are in a good agreement with a theory. The investigated configuration can be successfully used as a BSW launcher in on-chip all-optical integrated systems and work as a surface wave switch or modulator.
We propose different optical antenna structures for enhancing and confining the magnetic optical field. A common
feature of these structures are concave corners in thin metal films as locations of the enhanced magnetic field. This
proposal is inspired by Babinet's principle as the concave edges are the complementary structures to convex metal
corners, which are known to be locations of a strongly enhanced electric field. Bowtie antennas and the bowtie apertures
of appropriate size were shown to exhibit resonances in the infrared frequency range with an especially strong
enhancement of the electrical field in the gap between 2 convex metal corners. We show by numerical calculations, that
the complementary structures, the complementary bowtie aperture - the diabolo antenna - and the complementary bow
tie antenna - two closely spaced triangular apertures in a metal film with a narrow gap between two opposing concave
corners - exhibit resonances with a strongly enhanced magnetic field at the narrow metal constriction between the
concave corners. We suggest sub-wavelength circuits of concave and convex corners as building blocks of planar