摘要： Optical tweezing system arises from light-matter interactions which provide light driving force capable of directing a particle to a potential well and to maintain it in a stable position [1]. Recently it has been shown that the use of plasmonic structures makes it possible to overcome the problems of diffraction limit in dielectric since these structures are able to concentrate light in deep subwavelength volumes. The excitation of localized surface plasmons (LSPs) at metal nanoparticles (MNPs) can significantly amplify the electromagnetic field in the vicinity of the nanoantennas, providing an optical gradient force for near-field optical trapping. In such a way, by introducing plasmonic resonators inside tweezing systems, very deep and narrow potential well can be tailored to achieve optical tweezing down to subwavelength particles [2]. In references [3,4], we have numerically shown that the strong coupling occurring between a SOI waveguide and a gold MNP chain allows conceiving surface plasmon-based nanotweezers with efficient trapping of dielectric nanobeads, having radii down to 50 nm. In this contribution, we experimentally do the demonstration of trapping of dielectric nanobead with such structures. Fig. 1(a) and Fig. 1(b) present a general sketch of the system and a SEM image of a fabricated structure composed of 20 MNPs placed on top of a monomode SOI waveguide. The SOI waveguide has a height hSi=220 nm and a width wSi =500 nm. The MNPs are gold elliptic nanocylinders with radii rx=50 nm, ry=100 nm and a thickness h=30 nm. The gap g between two successive MNPs is close to 30 nm. Optical transmittance characterizations show that the structure presents a resonance around 1530 nm as shown in Fig. 1(c). We have shown that this structure, submerged in water (Fig. 1(d)), is able to trap small spherical beads of polystyrene having a radius r =500, 250 and 100 nm, with an incident nominal laser power of 6 mW. By considering thermodynamic equilibrium of the nanobead with the environment, we have used Boltzmann statistics to determine the stiffness of the trapping system, by recording the number of occurrences of positions occupied by the bead (Fig. 1(e)). Fig. 1(f) shows the potential energy well determined from the statistical position on a polystyrene bead with a diameter of 1 μm. We have determined stiffness kx=(5,10 ± 0,67).10-1 fN?nm-1?W-1 and ky = (2,61 ± 0,35) fN?nm-1?W-1, respectively along the waveguide direction x and along y.