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Aplikace metapovrchů pro strukturální zbarvení
Červinka, Ondřej ; Brzobohatý, Oto (referee) ; Šikola, Tomáš (advisor)
Color filters enable photosensors to obtain spectral composition of incoming radiation, be it to mimic human vision or to separate analytical signals. Efforts to increase the resolution of these photosensors lead to decrease in size of individual picture elements – pixels, which places increasing demands on the color filter technology. Conventional color filters operating on the principle of absorption of light in organic pigments are frequently used, but they are no longer meeting growing requirements of increasing sensor resolution. Here, metasurfaces comes to an aid, utilizing nanostructures to separate colors and thus creating structural coloration. There are many approaches to separate colors using metasurfaces, but each carries certain disadvantages with their principle of operation. In this thesis, we present a novel approach to separate colors which utilizes manipulation of radiation polarization. The presented color filter is first modeled and optimizes through numerical simulations and then manufactured using nanofabrication methods. Finally, the optical response of nanostructures is verified by several optical spectroscopy methods.
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Plasmonic Antennas
Kvapil, Michal ; Brzobohatý, Oto (referee) ; Novák, Stanislav (referee) ; Šikola, Tomáš (advisor)
Tato disertační práce pojednává o plazmonických anténách. Rezonanční vlastnosti plazmonických antén jsou studovány teoreticky i experimentálně. Teoretické výpočty jsou prováděny v programu Lumerical FDTD Solutions užitím numerické metody konečných diferencí v časové doméně. Pro experimentální studium byly antény vyrobeny pomocí elektronové litografie. Rezonanční vlastnosti vyrobených antén jsou studovány fourierovskou infračervenou spektroskopií. Práce se zaměřuje na studium rezonančních vlastností antén vyrobených na vrstvě nanokrystalického diamantu. Dále zkoumá možnost využití antén jako plazmonického senzoru funkcionalizovaného k detekci streptavidinu. Nakonec je představena anténa tvaru písmene V, u které dochází v důsledku porušení symetrie antény ke směrovému rozptylu dopadajícího světla. Tato směrovost se ovšem projevuje jen na vlnových délkách blízkých kvadrupólovému módu antény.
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Strong Coupling in Plasmonic Structurers
Gryga, Michal ; Brzobohatý, Oto (referee) ; Šikola, Tomáš (advisor)
This diploma thesis deals with numerical simulations of the optical response of plasmonic infrared antennas placed on silicon substrates with thin film of silicon dioxide and subsequently with fitting of scattering spectra by model of coupled harmonic oscillators. In this work, we study an influence of length of antennas on the strength of coupling of localized surface plasmons in the antennas with phonons in silicon dioxide film. Also, the influence of silicon dioxide film thickness on this coupling is investigated.
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Measurement of extinction spectra of optically trapped plasmon nano-particles
Flajšmanová, Jana ; Jonáš,, Alexander (referee) ; Brzobohatý, Oto (advisor)
This thesis deals with the dark-field imaging and the optical spectroscopy of optically trapped plasmonic nanoparticles. The optical trapping and the characterization of a single particle or multiple nanoparticles as well are demonstrated. The number of the optically trapped particles can be estimated from the dark-field scattering intensity. Experiments show the presence of the interparticle coupling among trapped metallic nanoparticles which has not been observed in case of dielectric particles. The scattering spectra of the plasmonic nanoparticles were compared with theoretical models based on the Mie theory and the Discrete dipole approximation.
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Measurement of resonant properties of plasmonic nanostructures in transmission and reflection mode of far-field spectroscopy
Klement, Robert ; Brzobohatý, Oto (referee) ; Šikola, Tomáš (advisor)
Far-field optical spectroscopy allows for measurement of plasmonic resonances on metallic nanostructures of various shapes and sizes when illuminated by continuous light. Employing dark-field microscopy makes it possible to measure scattering on a localised plasmon excited on a single, isolated nanostructure. For the purpose of these measurements an apparatus based on commercial dual microscope system Nanonics has been put together. Experiments carried out during work on this thesis have shown a great sensitivity of the apparatus in its present form, allowing to measure a plasmonic resonance of a single nanoparticle. Proposed improvements of the apparatus should lead to even greater sensitivity and precision of measurements in the near future.
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Dynamics of Microparticles Optically Trapped in Vacuum
Svak, Vojtěch ; Čižmár, Tomáš (referee) ; Marago, Onofrio (referee) ; Brzobohatý, Oto (advisor)
Mikročástice levitující ve vakuu pouze za pomoci silových účinků světla představuje mechanický systém, který je extrémně dobře izolován od okolních a jeho zdrojů šumu. Tato unikátní vlastnost poskytuje tomuto systému nevídanou citlivost na změny okolních podmínek. V předkládané práci je popsáno technické řešení experimentální sestavy pro optické chytání ve vakuu, která byla realizována v laboratořích skupiny levitační fotoniky Ústavu přístrojové techniky AVČR v Brně. Dále je prezentována experimentální studie dynamiky částice zachycené v kruhově polarizovaném optickém poli, které generuje nekonzervativní složku pole optické síly. Následuje experimentální pozorování a popis dynamiky dvou opticky vázaných mikročástic ve volném prostoru ve vakuu, což je konfigurace, která nebyla nikdypředtím realizována. Závěrem je představena zcela originální metoda pro odhad silového pole optické pasti založená na analýze stochastické trajektorie zachycené částice.
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Aplikace metapovrchů pro strukturální zbarvení
Červinka, Ondřej ; Brzobohatý, Oto (referee) ; Šikola, Tomáš (advisor)
Color filters enable photosensors to obtain spectral composition of incoming radiation, be it to mimic human vision or to separate analytical signals. Efforts to increase the resolution of these photosensors lead to decrease in size of individual picture elements – pixels, which places increasing demands on the color filter technology. Conventional color filters operating on the principle of absorption of light in organic pigments are frequently used, but they are no longer meeting growing requirements of increasing sensor resolution. Here, metasurfaces comes to an aid, utilizing nanostructures to separate colors and thus creating structural coloration. There are many approaches to separate colors using metasurfaces, but each carries certain disadvantages with their principle of operation. In this thesis, we present a novel approach to separate colors which utilizes manipulation of radiation polarization. The presented color filter is first modeled and optimizes through numerical simulations and then manufactured using nanofabrication methods. Finally, the optical response of nanostructures is verified by several optical spectroscopy methods.
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Orbital motion from optical spin: the extraordinary momentum of circularly polarized light beams
Svak, Vojtěch ; Brzobohatý, Oto ; Šiler, Martin ; Jákl, Petr ; Zemánek, Pavel ; Simpson, Stephen Hugh
We provide a vivid demonstration of the mechanical effect of transverse spin momentum in an\noptical beam in free space. This component of the Poynting momentum was previously thought\nto be virtual, and unmeasurable. Here, its effect is revealed in the inertial motion of a probe\nparticle in a circularly polarized Gaussian trap, in vacuum. Transverse spin forces combine with\nthermal fluctuations to induce a striking range of non-equilibrium phenomena. With increasing\nbeam power we observe (i) growing departures from energy equipartition, (ii) the formation of\ncoherent, thermally excited orbits and, ultimately, (iii) the ejection of the particle from the trap.\nOur results complement and corroborate recent measurements of spin momentum in evanescent\nwaves, and extend them to a new geometry, in free space. In doing so, we exhibit fundamental,\ngeneric features of the mechanical interaction of circularly polarized light with matter. The work\nalso shows how observations of the under-damped motion of probe particles can provide detailed\ninformation about the nature and morphology of momentum flows in arbitrarily structured light\nfields as well as providing a test bed for elementary non-equilibrium statistical mechanics.
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Optical binding of polystyrene particles in tractor beam
Damková, Jana ; Chvátal, Lukáš ; Oulehla, Jindřich ; Ježek, Jan ; Brzobohatý, Oto ; Zemánek, Pavel
The motion of a particle illuminated by a laser beam is usually driven by the photon flow due\nto the radiation pressure and therefore for particle trapping, one has to employ gradient forces. But in a tractor beam, objects are illuminated by the uniform light intensity and even so they can be pulled against the beam propagation. There have been developed several techniques how to create such a tractor beam. In our case, the tractor beam is created by two identical Gaussian beams that interfere under the defined angle. It creates the\nstanding wave, where in the transversal plane the particle is trapped by means of the gradient\nforce, but in the total beam propagation direction, the particle manipulation is driven by the non-conservative force. It is remarkable that this force can for the specific combinations of\nparameters pull the micro-particle against the beam propagation. This kind of behavior is\nbecause of the particle scattering where the majority of the incident photons is scattered in the forward direction and, based on the principle of action and reaction, the transfer of\nmomentum leads to a backward movement of the object. The pushing and pulling force is\nsensitive to the polarization of the laser beam, its incident angle and the particle size so this\ntechnique can be used for example for sorting of objects of different sizes.
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Strong Coupling in Plasmonic Structurers
Gryga, Michal ; Brzobohatý, Oto (referee) ; Šikola, Tomáš (advisor)
This diploma thesis deals with numerical simulations of the optical response of plasmonic infrared antennas placed on silicon substrates with thin film of silicon dioxide and subsequently with fitting of scattering spectra by model of coupled harmonic oscillators. In this work, we study an influence of length of antennas on the strength of coupling of localized surface plasmons in the antennas with phonons in silicon dioxide film. Also, the influence of silicon dioxide film thickness on this coupling is investigated.
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