Coupled mode enhanced giant magnetoplasmonics transverse Kerr effect

We show that the enhancement of the transverse magneto-optical Kerr effect of a smooth magnetic dielectric film covered by a noble metal grating, is strongly dependent on the precise geometry of this grating. Up till now this magnetoplasmonic enhancement was solely attributed to a nonreciprocal shift of the dispersion of the surface plasmon polariton resonances at the interface with the magnetized substrate. It is demonstrated that by hybridization of surface and cavity resonances in this 1D plasmonic grating, the transverse Kerr effect can be further enhanced, extinguished or even switched in sign and that without inverting or modifying the film’s magnetization. This strong geometrical dispersion and the accompanying anomalous sign change of the magneto-plasmonic effects in such systems has never been considered before, and might find interesting applications in sensing and nanophotonics.Web of Science2119217552174

Plasmonic behavior of III-V semiconductors in far-infrared and terahertz range

Background: In this article, III-V semiconductors are proposed as materials for far-infrared and terahertz plasmonic applications. We suggest criteria to estimate appropriate spectral range for each material including tuning by fine doping and magnetic field. Methods: Several single-crystal wafer samples (n, p-doped GaAs, n-doped InP, and n, p-doped and undoped InSb) are characterized using reflectivity measurement and their optical properties are described using the Drude-Lorentz model, including magneto-optical anisotropy. Results: The optical parameters of III-V semiconductors are presented. Moreover, strong magnetic modulation of permittivity was demonstrated on the undoped InSb crystal wafer in the terahertz spectral range. Description of this effect is presented and the obtained parameters are compared with a Hall effect measurement. Conclusion: Analyzing the phonon/free carrier contribution to the permittivity of the samples shows their possible use as plasmonic materials; the surface plasmon properties of semiconductors in the THz range resemble those of noble metals in the visible and near infrared range and their properties are tunable by either doping or magnetic field.Web of Science13art. no. 1

Mueller matrix optical and magneto-optical characterization of Bi-substituted gadolinium iron garnet for application in magnetoplasmonic structures

A ferromagnetic garnet, used as a magneto-optical (MO) material in magneto-photonic and magneto-plasmonic structures, is characterized. We present a general procedure to determine optical and magneto-optical functions of the magneto-optic garnet by using Mueller matrix ellipsometry. In the first step, the optical functions (the refractive index spectra) of the (CaMgZr)-doped gallium-gadolinium garnet (sGGG) substrate and the Bi-substituted gadolinium iron garnet Gd1.24Pr0.48Bi1.01Lu0.27Fe4.38Al0.6O12 (Bi:GIG) are obtained in the spectral range from 0.73 eV to 6.42 eV (wavelength range 193 nm – 1.7 μm). Subsequently, the spectra of the magneto-optical tensor components are obtained by applying an external in-plane magnetic field in longitudinal and transverse geometry. The obtained functions are then used to fit the Mueller matrix spectra of a magneto-plasmonic structure with a gold grating on the magneto-optic garnet layer. This structure has recently been demonstrated to have strongly enhanced transverse magneto-optic Kerr response at visible and near-infrared frequencies. By taking possible fabrication imperfections (surface roughness, residual photo-resist layer, thickness deviation) into account, the measured strongly enhanced MO response fits very well to the numerical model predicting these exaltations.Web of Science491919190

Magneto-optical properties of InSb for terahertz applications

Magneto-optical permittivity tensor spectra of undoped InSb, n-doped and p-doped InSb crystals were determined using the terahertz time-domain spectroscopy (THz-TDS) and the Fourier transform far-infrared spectroscopy (far-FTIR). A Huge polar magneto-optical (MO) Kerr-effect (up to 20 degrees in rotation) and a simultaneous plasmonic behavior observed at low magnetic field (0.4 T) and room temperature are promising for terahertz nonreciprocal applications. We demonstrate the possibility of adjusting the the spectral rage with huge MO by increase in n-doping of InSb. Spectral response is modeled using generalized magneto-optical Drude-Lorentz theory, giving us precise values of free carrier mobility, density and effective mass consistent with electric Hall effect measurement.Web of Science611art. no. 11502

Teoretická a experimentální studie nových magnetoplasmonových nanostruktur.

Import 25/11/2014This work studies the enhancement of the transverse magneto-optical Kerr effect by exploiting extraordinary resonances occurring in 1D periodic grating. The 1D periodic gold grating structure was designed, described, numerically simulated and fabricated. A rigorous CoupledWave Algorithm (RCWA) developed for parallel computing is used for the theoretical study of resonant modes in magnetoplasmonic gratings and for analysis of optical and magneto-optical data measured by Mueller matrix ellipsometry. The impact of coupling between Fabry-Perot modes inside grating air-gaps and surface plasmon mode at the interface between gold and MO garnet layer is studied via spectra of specular reflectivity and for the various angles of incidence. In a first step, the optical functions of the (CaMgZr)-doped gallium-gadolinium garnet (sGGG) substrate and the Bisubstituted gadolinium iron garnet (Bi :GIG) are obtained in the spectral range from 0.73 eV to 6.42 eV (wavelength range 193 nm – 1.7 μm). Subsequently, the spectra of the magneto-optical tensor components are obtained by applying an external in-plane magnetic field in longitudinal and transverse geometry. The obtained functions are then used for numerical simulations demonstrating that by hybridization of surface and cavity resonances in this 1D plasmonic grating, the transverse Kerr effect can be further enhanced, extinguished or even switched in sign and that without inverting or modifying the film’s magnetization. To confirm theoretical results a set of samples, gratings with a different width of an air-gap, was fabricated using electron beam lithography and liftoff technique. To be able to reproduce Mueller matrix data from the samples, the models describing realistic structures were further developed and optimized. Experimental measurements of real structures confirm transverse MO effect enhancement using magnetoplasmonic effects and prove applicability of numerical models.Tato práce je zaměřena na studium zesílení transversánního magnetooptického Kerrova jevu pomocí resonančních módůu v jednodimenzionální (1D) periodické mřížce. Studovaná struktura sestává ze zlaté mřížky na dielektrickém substrátu tvořenám magnetooptickým granátem. Dva základní typy resonančních módůu, resonance ve vzduchové kavitě mřížky a resonance povrchového plasmonu na rozhraní mezi zlatem a magnetooptickým granátem, jsou studovány samostatně a posléze je analyzován vliv jejich interakce na optickou a magnetooptickou odezvu. Optická a magnetooptická odezva je studována pomoci spekter spekulární reflektivity pro p-polarizovanou vlnu. Magnetoplasmonická struktura byla teoreticky studována prostřednictvím numerických simulací a posléze byl navrhnut a vyroben soubor vzorků pro experimentální optická a magnetooptická měření.Pro numerické simulace byl implementován algoritmus vázaných vln (Rigorous CoupledWave Algorithm, RCWA) pro 1D periodické systémy, který byl paralelizován pro spektrální úlohy. Experimentální optická a magnetooptická data byla získána pomocí spektroskopické elipsometrie Muellerových matic ve spektrálním rozsahu 0.73-6.42 eV (193 nm-1.7 μm). Elipsometrie Muellerových matic byla rovněž použita pro určení optických funkcí použitých materiálů. Pro substrát byl použit galium-gadoliniový granát dopovaný pomoci Ca, Mg a Zr. Na substrátu byla připravena vrstva magnetooptického, Bi-substituovaného gadolinium - železitého granátu (Bi:GIG). V dalším kroce bylo na vrstvu magnetooptického granátu (Bi:GIG) na sGGG substrátu aplikováno vnější magnetické pole v transvezální a longitudinální magnetooptické konfiguraci a byly určeny magnetooptické funkce. Takto získané materiálové parametry jsou použity v numerických simulacích. Podrobnou analýzou je předvedeno ovlivnění interakce mezi plasmonovým módem a módem v kavitě mřížky změnou geometrických parametru mřížky. Následně je analyzován vliv interakce na transversální magnetooptickou odezvu a je demonstrován proces zesílení, ztlumení nebo dokonce změny znaménka Kerrova transversálního magnetooptikého jevu aniž by byla změněna magnetizace. Pro potvrzení teoretických výsledků byl navrhnut soubor vzorků s rozdílnou šířkou vzduchové mezery. Vzorky byly vyrobeny elektronovou litografií a procesem liftoff. Pro vyrobené vzorky byl vyvinut teoretický model, který byl následnou numerickou optimalizací fitován na experimentální optická data, čímž byl získán model věrně popisující optickou aktivitu vyrobených struktur. Shoda numerických dat, získaných pomocí optimalizovaného modelu a změřených experimentálních dat potvrdila dřívější získané teoretické poznatky o zesílení transversálního magnetooptického jevu pomocí magnetoplasmonické struktury a jeho ovlivnění vzájemnou interakcí resonančních módůu.Prezenční516 - Institut fyzikyvyhově

Spektroskopická elipsometrie a metoda efektivního prostředí

Prezenční457 - Katedra aplikované matematikyNeuveden

Modelling of optical response form periodic systems

Import 29/09/2010Tato diplomová práce je zaměřena na modelování optické odezvy od periodických struktur. V první části jsou řešeny Maxwellovy rovnice pro struktury planárních vrstev pomoci Berremanova a Yehova přístupu. Výsledné vztahy jsou demonstrovovány na příkladu planární zlaté vrstvy s excitovanou plazmonovou resonancí. Hlavní část práce je věnována modelování periodických lamelárních (1D) mřížek pomoci metody vázaných vln, RCWA (Rigorous Coupled Wave Analysis). Pomoci S-maticoého algoritmu je modelován fotonický krystal s nereciproými optickými vlastnostmi. Je diskutována přesnost výpočtu při použití konečného počtu členů Fourierovy aproximace nespojité funkce permitivity a metoda Fourierovy faktorizace pro zlepšení konvergence. Pro zpětnou charakterizaci materiálu je uvedeno zobecnění elipsometrických měření pro připad jednoosé anisotropie.This master thesis is focused to modeling of the optical response from periodical optial structures. The first part is devoted the Berreman and Yeh approach for solving the Maxwell equations in planar layers medium. Theoretical results are demonstrated on the system with sufrace plasmon resonance in the gold layer. The main part of the work is devoted to the modeling of one dimensional periodical structures with the RCWA (Rigorous Coupled Wave Analysis) method. Photonics crystals with non-reciprocity effect are modeled using using S-matrix algorithm. The effect of truncation Fourier series and Fourier factorization is demonstrated. Generalization of spectroscopic ellipsometry method for characterization of uniaxial anisotropic material is presented.457 - Katedra aplikované matematikyvýborn

Soft magnetic properties of as-deposited FeCoAlN films studied using magneto-optic magnetometry

The longitudinal magneto-optical Kerr effect (MOKE) is used to investigate the magnetic properties of nanogranular ferromagnetic FeCoAlN films. In-plane hysteresis loops of as-deposited samples in the longitudinal and transversal direction to applied field are compared with the volume loops obtained by the M–H inductive tracer. All loops show excellent soft magnetic properties with the coercive field of about 4 Oe and in-plane magnetic uniaxial anisotropy. The coherent rotation of magnetization followed by nucleation of domains magnetized along the easy axis of the film is observed. It is shown that external magnetic field applied during the preparation for the plasma confinement induces magnetic anisotropy in the films

Magnetoplasmonic nanograting geometry enables optical nonreciprocity sign control

We experimentally demonstrate a disruptive approach to control magnetooptical nonreciprocal effects. It has been known that the combination of a magneto-optically (MO) active substrate and extraordinary transmission (EOT) effects through deep-subwavelength nanoslits of a noble metal grating, leads to giant enhancements of the magnitude of the MO effects that would normally be obtained on just the bar substrate. This was demonstrated both in the transmission configuration, where the OET is directly observed, as well as in reflection configuration, where an increase of a transmitted power results in a decrease in reflected power. We show here that even more than just an enhancement, the MO effects can also undergo a sign reversal by achieving a hybridization of the different types of resonances at play in these EOT nanogratings. By tuning the geometrical profile of the grating's slits, one can engineer - for a fixed wavelength and fixed magnetization - the transverse MO Kerr effect (TMOKE) reflectivity of such a magnetoplasmonic system to be enhanced, extinguished or inversely enhanced. We have fabricated gold gratings with varying nanoslit widths on a Bi-substituted gadolinium iron garnet and experimentally confirmed such a behavior using a customized magneto-optic Mueller matrix ellipsometer. This demonstration allows new design paradigms for integrated nonreciprocal circuits and biochemical sensors with increased sensitivity and reduced footprint.Web of Science2624315663155

Tin reduction from fluorine doped tin oxide for silicon nanowire-based solar energy harvesting and storage

Hydrogen plasma reduction of fluorine doped tin oxide is a beneficial method to form tin nanodroplets on the sample surface directly in the plasma-enhanced chemical vapor deposition reactor. The formation of catalyst droplets is a crucial initial step for vapor-liquid-solid growth of silicon nanowires for radial junction solar cells and solar fuel cell technology. We present an original optical model which allows us to trace the formation process on fluorine doped tin oxide on soda-lime glass substrate from the in situ data and is in a good agreement with the spectroscopic ellipsometry data measured before and during the reduction process. The model reproduces well the phase shift introduced by a transition double layer in fluorine doped tin oxide which acts as a barrier against the sodium diffusion. Furthermore, we study the process of tin reduction from fluorine doped tin oxide in a real time and compare estimated amount of produced metallic tin with images from scanning electron microscopy.The proposed approach is very important for in situ real-time monitoring of the one-pump-down fabrication process used to grow nanowires and form radial junction devices.Web of Science2920314773146