A5080465967- Quantum optics and atomic interactions
- Atomic and Subatomic Physics Research
- Cold Atom Physics and Bose-Einstein Condensates
- Laser Design and Applications
- Spectroscopy and Laser Applications
- Laser-Matter Interactions and Applications
- Solid State Laser Technologies
- Plasma Diagnostics and Applications
- Spectroscopy and Quantum Chemical Studies
- Advanced Fiber Laser Technologies
- Crop Yield and Soil Fertility
- Advanced Frequency and Time Standards
- Agriculture, Plant Science, Crop Management
- Semiconductor Lasers and Optical Devices
- Atomic and Molecular Physics
- Gold and Silver Nanoparticles Synthesis and Applications
- Random lasers and scattering media
- Laser Applications in Dentistry and Medicine
- Plasma Applications and Diagnostics
- Photonic and Optical Devices
- Plant Growth Enhancement Techniques
- Mass Spectrometry Techniques and Applications
- Phosphorus and nutrient management
- High voltage insulation and dielectric phenomena
- Hemodynamic Monitoring and Therapy
Institute of Electronics
2010-2024
Bulgarian Academy of Sciences
2009-2024
Institute of Physics Belgrade
2007
Observatoire Cantonal de Neuchâtel
2004-2005
Technical University of Sofia
1998
Abstract Recent advances in nonlinear optics, hot electrons for renewable energy (e.g., solar cells and water‐splitting), acousto‐optics, nanometalworking, nanorobotics, steam generation, photothermal cancer therapy are reviewed here. In all these areas, one of the key enabling properties is ability metallic nanoparticles to harvest control light at subwavelength scale by supporting coherent electronic oscillations, called localized surface plasmon resonances (LSPRs). Various physical...
This work reveals that diOctadecylamine (diODA) outperforms its primary amine counterpart ODA in intra- and intermolecular order, forming passivation monolayers on 5 nm small gold nanoparticles. We support this conclusion by meticulously analyzing the differences Fourier Transform Infrared (FTIR) spectrum of diODA molecules their pure- coordinated-to-gold-nanoparticle phases. Detailed spectral data are scarce literature absent for diODA-passivated nanoparticles, whose merits have gone...
The saturation behavior of absorption and fluorescence spectra on the D2 line Cs is presented, demonstrating a significant difference between open closed transitions. vapor confined in an extremely thin cell (ETC) with widely tunable thickness L=(0.5-3)λ, where λ light wavelength. In regime, transition demonstrates enhanced narrow spectral interval due to Dicke effect, while one only velocity-selective dip absorption. transitions shows reduced dips, enhancing their contrast ETC thickness....
We describe a technique to optically characterize superparamagnetism. Faraday rotation measurements are performed on superparamagnetic nanocomposite using small alternating current magnetic fields. The superparamagnetism of the iron oxide nanoparticles causes signals at uneven harmonics field frequency. These provide information moment nanoparticles. Dia- and paramagnetism do not cause higher harmonics, resulting in high sensitivity superparamagnetism, even samples with large dia- or...
The sub-natural-width $N$-type resonance in {\Lambda}-system, on the $D_2$ line of Cs atoms is studied for first time presence a buffer gas (neon) and radiations two continuous narrow band diode lasers. $L$ = 1 cm long cell used to investigate process. magnetic field $^{133}$Cs shown split into seven or eight components, depending laser radiation directions. results obtained indicate that levels $F_g$ 3, 4 are initial final N formation. experimental with agree well theoretical curves.
We present the Hanle EIT resonances obtained from various segments of Gaussian laser beam cross-section, selected by moving small aperture (placed in front detector) radially along beam. Significant differences lineshapes are observed depending on whether central or outer parts detected. The line narrowing and two counter-sign peaks occur at outer, less intense theoretical model suggests that wings result interference light coherently prepared atoms coming part By blocking detector,...
Abstract Alkali metal vapors enable access to single electron systems, suitable for demonstrating fundamental light-matter interactions and promising quantum logic operations, storage sensing. However, progress is hampered by the need robust repeatable control over atomic vapor density associated optical depth. Until now, a moderate improvement of depth was attainable through bulk heating or laser desorption – both time-consuming techniques. Here, we use plasmonic nanoparticles convert light...
We have conducted a new comparison of gold nanoparticles functionalized by primary- and secondary amine with the same chain length. Our hypothesis suggests that adaptive steric conformation molecular branches makes marked additional contribution to well-established role ligand characterize importance this factor based on diOctadecylamine (diODA) Octadecylamine (ODA) passivated using high-resolution transmission electron microscopy (HR-TEM) selective area diffraction (SAED). The results...
Experimental and theoretical studies are presented related to the ground-state magneto-optical resonance observed in cesium vapor confined an extremely thin cell (ETC), with thickness equal wavelength of irradiating light. It is shown that utilization ETC allows one examine formation a on individual hyperfine transitions, thus distinguishing processes resulting dark (reduced absorption) or bright (enhanced formation. We report experimental evidence sign reversal Cs atoms ETC. A model...
We present high resolution laser spectroscopy of Cs vapours confined in a unique optical cell sub-micrometric and micrometric thickness, where strong spatial anisotropy is pres- ent for the time interaction between atoms radi- ation. Similarly to spectra selective specular reflection, Doppler-free absorption fluorescence are observed, not revealing cross-over resonances that will be useful frequency stabilisation, provided cheap com- pact. A new resonance closed transition studied,...
Observation of electromagnetically induced transparency (EIT) and enhanced velocity selective optical pumping (VSOP) signals in a micrometric cell with cesium is reported. The line shape non-linear features observed the case fluorescence direction parallel to windows transmission spectra along propagation probe beam show considerable differences spectral profile. A theoretical model based on five level Bloch equations used simulate spectra. Doppler convolution includes all possible...
We report on the expressed atomic spin-polarization protection properties of thin layers Octadecylamine capped gold-nanoparticles applied to inner surface an alkali metal vapor cell. The work aims reveal potential using appropriately functionalized gold nanoparticles as a novel approach forming efficient coatings vacuum cells for spectroscopy. performed layer characterization uses parameters electromagnetically induced transparency/absorption resonances observed in Hanle configuration. show...
We present a rate-equation theoretical model describing the optical pumping processes on K D 1 line and we then discuss their influence electromagnetically induced transparency resonance parameters.We also comparison with results of an experiment performed in cells containing pure alkali metal or added few torrs buffer gas.The shows that, last case, complete Maxwellisation atomic population velocity distribution, along overlapping Doppler profiles transitions from ground-states typical K,...
A model for description of the shapes coherent population trapping (CPT) resonances at different geometries of excitation and observation is developed. The numerical calculations, based on irreducible tensor operator formalism, take into account experimental geometry, velocity distribution atoms, Gaussian laser beam intensity high rank polarization moments (HRPM). results laser beam diameters, aperture of detection, position photodetector etc. are compared with data. method of the proposed.
We present a systematic quantitative comparison of the performance parameters two Extended Cavity Diode Lasers (ECDL), stabilized to Doppler and sub-Doppler profiles. The experimental study is carried out on Rb atomic vapour cells. frequency shift resonance under investigation with respect reference measured analyzed, in dependence modulation amplitude, cell temperature, laser power, applied magnetic field misalignment pump-probe beams angle. Allan variance for both locking methods. It shows...
We report on a novel behavior of the electromagnetically induced absorption (EIA) resonance observed D 2 line Cs for atoms confined in cells with micrometric thickness. With enhancement light intensity, EIA amplitude suffers from fast reduction, and even at very low intensity ( W < 1 mW/cm ), sign reversal takes place transparency (EIT) is observed. Similar transformation to EIT one not conventional cm-size cells. A theoretical model proposed analyze physical processes behind intensity....
The purpose of this communication is to summarize and compare the results obtained under project "New all-optical systems methods for magnetic electromagnetic field measurement", financed by EC (contract G6RD-CT-2001-000642). main aim investigation potential different approaches based on effect Coherent Population Trapping (CPT) measurement. investigated are: (i) CPT prepared coupling pairs non-degenerate Zeeman sublevels belonging two ground-state hyperfine components alkali atoms means...
Experimental results are presented about the transformation of electromagnetically induced absorption resonance into transparency one.The role depolarization excited state on D2 line Cs atoms exposed to different confinements is discussed.
Numerical simulations are used to obtain the amplitudes and widths of nonlinear resonances related different ranks tensor components &rgr;<i><sup>k</sup><sub>q</sub></i> in dependence on atomic system parameters, laser field power (Rabi parameter - d.E/ℏ). The main attention is paid effect velocity distribution atoms hexadecapole (<i>k</i> = <i>4</i>) their influence fluorescence and/or absorption signals. A detailed examination our basic equations allows us directly find out a...