This diploma thesis deals with optimization of analysis process and measuring antibiotics induced changes in E. coli cells via Raman spectroscopy, LTRS and microfluidic systems. Optical micromanipulation by a laser beam allows noncontact and noninvasive manipulation of objects on scale 10^-5–10^-8 m, for example bacterial cells. Microfluidic device consists of microchannels and microchambers in transparent polymer and it is used for isolation, observation and cultivation of bacterial cells. Combination of these methods gives an effective tool for observation, manipulation and analysis of microorganisms. E. coli is a microorganism potentially pathogenic for humans and faster detection of its sensitivity to antibiotic treatment would make the whole process of diagnostics and treatment easier. We performed laser tweezer-Raman spectroscopy and conventional Raman spectroscopy of bacterial cells and cells under antibiotic stress and collected Raman spectra and characteristic areas were compared with literature to establish the reliability and usefulness of this method.

In this thesis two previously separate fields of study are brought together: optical micromanipulation and ultrashort laser research. Here, the benefits of combining the high peak powers of ultrashort pulsed lasers and conventional optical micromanipulation techniques are explored. As optical trapping has been studied extensively, the focus of this research is on optical guiding. Moreover, the emphasis is on the use of Bessel beams as these have been shown to offer greater guiding distances than comparable Gaussian beams. The studies within this thesis show that optical guiding in Bessel and Gaussian beams is governed by the average power of the laser. However, the benefits of guiding with ultrashort pulsed lasers to exploit multi-photon processes become evident as the demonstration of simultaneous optical guiding and second harmonic generation in microscopic nonlinear crystal fragments is detailed. This work is developed by using ultrashort pulses to induce two-photon excitation-induced fluorescence in the guiding medium. This allows direct visualisation of the beam-particle interaction and measurement of the reconstruction of the Bessel beam around an object. Some studies using two-photon excitation to investigate Bessel beam penetration through turbid media are discussed. Finally, the work is concluded by exploring the use of pulsed white-light lasers in optical guiding. The wavelength-dependent propagation and reconstruction properties of the white-light Bessel beam are studied before some preliminary optical guiding experiments are discussed. From this, the broad bandwidth of the supercontinuum source is found to offer extended guiding distances in Gaussian beams thereby negating the need for Bessel beams.

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In this thesis devices for controlling the flow of surface plasmon polaritons are described. Dielectric and metallic nanostructures were designed for this purpose, and characterized by leakage radiation microscopy in real and in reciprocal spaces. Manipulation of surface plasmons by dielectric lenses and gradient index elements is presented, and negative refraction, steering and self-collimation of surface plasmons in one- and two-dimensional plasmonic crystals is demonstrated. The achieved degree of control was applied for routing of nanoparticles by optical forces, as well as for two methods of enhancing the figures of merit of plasmonic refractive index sensors, based on the one hand on Fano resonances natural to leakage radiation microscopy, and on the other hand on anisotropie plasmonic bandstructures.

L’effet thermocapillaire (ou Marangoni) est la résultante mécanique d’un gradient de tensioninterfaciale induit par la présence d’un gradient de température sur une interface fluide. Il semanifeste par (i) la migration d’un objet fini (goutte, bulle) immergé, et (ii) une déflexion del’interface. Sa nature interfaciale le rend particulièrement pertinent à petite échelle, notammenten microfluidique diphasique. Ce travail de thèse montre comment un effet thermocapillaireinduit localement par chauffage laser peut être utilisé pour produire des composants optofluidiquesélémentaires (vanne, aiguillage, échantillonneur), et en présente une étude quantitative.La déstabilisation d’un jet microfluidique forcée par laser, conduisant à sa rupture, est égalementprésentée et caractérisée. Cette « boîte à outils » optique fournit ainsi une approche sans contact,pour produire et manipuler des gouttes en microfluidique digitale sans nécessité d’une microfabricationdédiée. Par ailleurs, afin de caractériser sur des temps longs les gouttes produites,et ainsi considérer des populations statistiquement significatives, un dispositif optoélectroniquesimple pour mesurer les gouttes et leur vitesse en temps réel a également été développé. / The thermocapillary (or Marangoni) effect is the mechanical result of an interfacial tension gradientinduced by a temperature gradient on a fluid interface. This effect manifests itself byinducing (i) the migration of an immersed finite-size object (droplet, bubble), and (ii) a deflexionof the interface. Due to its interfacial nature, the Marangoni effect is particularly relevantat small length scales, especially in the context of two-phase microfluidics. This thesis aims atapplying the thermocapillary effect locally induced by laser heating, in order to create some basicoptofluidic actuators (valve, switch, sampler). A quantitative study of these actuators is presented.The laser-forced destabilization of a co-flowing microfluidic jet, leading to its breakup,is also investigated. This “optical toolbox” represents a non-contacting, and microfabricationfreeapproach for the production and handling of droplets in digital microfluidics. Moreover, tocharacterize these droplet over long times, thus considering statistically significant populations,a simple optoelectronic device has been developed for measuring the size and velocity of thedroplets in real time.

Ce manuscrit s'inscrit dans le contexte du contrôle de la propagation des plasmons de surface. A cet effet, des nanostructures diélectriques et métalliques ont été conçues et caractérisées par microscopie à champ de fuite dans les espaces réels et réciproques. La manipulation des plasmons de surface à l'aide de lentilles diélectriques et d' éléments à gradient d'indice est présentée, et la réfraction négative, la direction et l'auto-collimation des plasmons de surface dans des cristaux plasmoniques à une ou deux dimensions sont démontrées. Ces résultats ont été utilisés pour le guidage de nanoparticules à l'aide de forces optiques, ainsi que pour deux méthodes permettant de renforcer le facteur de mérite de sondes plasmoniques de variation d'indice de réfraction, basées l' une sur les résonances de Fano naturelles de la microscopie à champ de fuite, et pour la seconde sur les structures des bandes plasmoniques anisotropes. / In this thesis devices for controlling the flow of surface plasmon polaritons are described. Dielectric and metallic nanostructures were designed for this purpose, and characterized by leakage radiation microscopy in real and in reciprocal spaces. Manipulation of surface plasmons by dielectric lenses and gradient index elements is presented, and negative refraction, steering and self-collimation of surface plasmons in one- and two-dimensional plasmonic crystals is demonstrated. The achieved degree of control was applied for routing of nanoparticles by optical forces, as well as for two methods of enhancing the figures of merit of plasmonic refractive index sensors, based on the one hand on Fano resonances natural to leakage radiation microscopy, and on the other hand on anisotropie plasmonic bandstructures.