We propose a novel approach in optical trapping exploiting mesoscopic photonic crystal microcavities. Full light confinement in mesoscopic photonic crystal membranes, forming a mesoscopic self-collimating 1D Fabry-Pérot cavity, was theoretically predicted and experimentally verified by the authors in previous papers. In this paper, we numerically demonstrate a high performance MPhC microcavity for optical trapping of fine particulate matter in air. The MPhC cavity has been simulated by 3D FDTD simulations while the trapping potential has been evaluated by means of the gradient force density convolution method. We numerically show that it is possible to obtain very high trapping potential for polystyrene particles having radii as small as 245 nm.
In this contribution, the efficient trapping of low refractive index nanoparticles, with radii down to 50 nm, is numerically demonstrated in gold dimers coupled with SOI waveguides. This coupled scheme provides a strong excitation of the plasmonic resonators  that, in combination with the field enhancement occurring in dimers, leads to an ultra-efficient trapping. Without any needs of cumbersome optical elements, this excitation scheme does not affect the overall portability of the system and stands out as a perfect candidate for integration inside microfluidic systems , for nanoparticle immobilisation and analysis. The possibility to trap smaller nanoparticle, with radii down to 5 nm, having higher refractive index will be discussed. The impact of the geometrical parameters of the dimer on the optomechanical well stiffness and depth, the optimisation strategies, the simple fabrication approach and the ongoing experimental demonstration will be as well detailed.<p> </p> M. Fevrier, P. Gogol, A. Aassime, R. Megy, C. Delacour, A. Chelnokov, A. Apuzzo, S. Blaize, J.-M. Lourtioz et B. Dagens, ≪Giant Coupling Effect between Metal Nanoparticle Chain and Optical Waveguide,≫ <i>Nano Letters</i>, pp. 1032-1037, 2012.<p> </p> G. Magno, A. Ecarnot, C. Pin, V. Yam, P. Gogol, R. Megy, B. Cluzel et B. Dagens, ≪Integrated plasmonic nanotweezers for nanoparticle manipulation,≫ <i>Optics Letters</i>, vol. 41, n° 16, 2016.
Mesoscopic photonic crystal based mirrors are exploited to theoretically conceive and analyse a novel high-Q factor Fabry-Perot-like cavity. Thanks to a beam focussing effect in reflection these mirrors efficiently confine and stabilise a mode inside a planar cavity, even for non-paraxial small beam sizes, mimicking the behaviour of curved mirrors. Furthermore, these mirrors show a higher reflectivity with respect to their standard distributed Bragg reflector counterparts, which allow these cavities to reach a maximum Q factor higher than 10<sup>4</sup> when 5-period-long mirrors are considered. Moreover, these cavities show other intriguing features as a beamforming behaviour and transverse translational invariance offered by the planar geometry. The latter opens interesting possibilities for lasing and biodetection. The optimization of the cavity size and the performances in terms of Q factor, energy storage and confinement are detailed.
Ultra-short vertical plasmonic couplers were devised for the efficient excitation of long-range surface-polariton-plasmon mode, in the visible regime, between a polymeric waveguide and a plasmonic waveguide in two different configurations. Numerical simulations suggest the realization of coupling efficiencies as high as 90% and insertion losses as low as −5.5 dB , with a coupling length of few micrometers. Thus the proposed design clearly proves that is possible to optimize contemporaneously the coupling efficiency and the coupling length. Therefore the compactness and the lower fabrication requirements make the proposed device very promising in a variety of applications.