Siim PikkerUniversity of Tartu · Institute of Physics
Siim Pikker
PhD
Working in the field of micro and nanooptics with plasmonic and polaritonic systems.
About
35
Publications
10,606
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350
Citations
Introduction
Additional affiliations
November 2018 - present
May 2020 - December 2020
November 2018 - April 2020
Publications
Publications (35)
Strong coupling between molecules and confined light modes of optical cavities to form polaritons can alter photochemistry, but the origin of this effect remains largely unknown. While theoretical models suggest a suppression of photochemistry due to the formation of new polaritonic potential energy surfaces, many of these models do not account for...
Strong coupling between molecules and confined light modes of optical cavities to form polaritons can alter photochemistry, but the origin of this effect remains largely unknown. While theoretical models suggest a suppression of photochemistry due to the formation of new polaritonic potential energy surfaces, many of these models do not account for...
Metallic nanowires (NWs) are sensitive to heat treatment and can split into shorter fragments within minutes at temperatures far below the melting point. This process can hinder the functioning of NW-based devices that are subject to relatively mild temperatures. Commonly, heat-induced fragmentation of NWs is attributed to the interplay between hea...
Metallic nanowires (NWs) are sensitive to heat treatment and can split into shorter fragments within minutes at temperatures far below the melting point. This process can hinder the functioning of NW-based devices that are subject even to relatively mild temperatures. Commonly, heat-induced fragmentation of NWs is attributed to the interplay betwee...
A refractive lens is one of the simplest, most cost-effective and easily available imaging elements. Given a spatially incoherent illumination, a refractive lens can faithfully map every object point to an image point in the sensor plane, when the object and image distances satisfy the imaging conditions. However, static imaging is limited to the d...
A refractive lens is one of the simplest, cost-effective and easily available imaging elements. With a spatially incoherent illumination, a refractive lens can faithfully map every object point to an image point in the sensor plane, when the object and image distances satisfy the imaging conditions. However, static imaging is limited to the depth o...
Samarium-doped CdWO4 thin films were prepared by pulsed laser deposition; their morphological, structural and photoluminescent properties were studied. In the luminescence spectra of the films with thicknesses ranging from 100 nm down to 2 nm, strong Sm3+-related emission dominated and efficient host-to-guest energy transfer was observed. Also for...
Phase-pure crystalline micropowder samples of BaGeF6 were prepared and studied under excitation by tuneable synchrotron radiation and 10 keV electron beam. Time-resolved photoluminescence emission and excitation spectra and a set of single emission decay curves were recorded at 7 K for the exciting photon energy region of 4.3–45 eV. Several intrins...
Airborne transmission of SARS-COV-2 virus has been recognized as an important pathway for infection. In many countries wearing a mask has become one of the prevention measures. In fact, the only implemented active measure to reduce the airborne transmission of the virus (Noorimotlagh et al 2021). Good ventilation is rather a recommendation and not...
In the current study we show that the combustion of sol-gel derived alcogels with specifically tailored composition leads to the release of silica nanoparticles from the burning alcogel in a controlled manner which enables direct deposition of the released nanoparticles into low-density silica thick films. The process has some similarities to flame...
When the enhanced electromagnetic field of a confined light mode interacts with photoactive molecules, the system can be driven into regime of strong coupling, where new hybrid light-matter states, polaritons, are formed. Polaritons, manifested by the Rabi split in the dispersion, have shown potential for controlling chemistry of the coupled molecu...
When the enhanced electromagnetic field of a confined light mode interacts with photoactive molecules, the system can be driven into regime of strong coupling, where new hybrid lightmatter states, polaritons, are formed. Polaritons, manifested by the Rabi split in the dispersion, have shown potential for controlling chemistry of the coupled molecul...
Our work based on previous studies [1, 2] confirms, that simple aluminum nanostructures can be utilized as effective plasmonic resonators over a broad range of frequencies and wavelengths. The nanostructured surfaces, fabricated by electron-beam lithography demonstrated relatively narrow-band resonances and are suitable for various plasmonic applic...
This poster shows that summing up the intensity normalized angle dependent emission spectra of a lower polariton from a leaky Fabry-Perot type cavity can help to identify the vibrational modes participating in the energy transfer from the exciton reservoir.
Programmable self-assembly of nucleic acids enables the fabrication of custom, precise objects with nanoscale dimensions. These structures can be further harnessed as templates to build novel materials such as metallic nanostructures, which are widely used and explored because of their unique optical properties and their potency to serve as compone...
Tin oxide is considered to be one of the most promising semiconductor oxide materials for use as a gas sensor. However, a simple route for the controllable build-up of nanostructured, sufficiently pure and hierarchical SnO2 structures for gas sensor applications is still a challenge. In the current work, an aqueous SnO2 nanoparticulate precursor so...
Noble metal nanoparticles are prospective of enhancement light trapping, absorption and overall efficency in solar cells. Light induced plasmonic electric field concentrated near such particles can support absorption process in the absorber layer of the cell. In spite of the clarity of this general principle, discussions about the most effective si...
Silica-gold core-shell nanoparticles were used for plasmonic enhancement of rare earth fluorescence in sol-gel-derived TiO2:Sm3+ films. Local enhancement of Sm3+ fluorescence in the vicinity of separate gilded nanoparticles was revealed by a combination of dark field microscopy and fluorescence spectroscopy techniques. An intensity enhancement of S...
Titania films covered by gold nanoparticles are prepared by combination of spray pyrolysis and spin-coating methods. Proposed combination of techniques is prospective for photovoltaic coatings with plasmonic properties. The prepared TiO2 films with Au nanoparticles demonstrate variation in size of the gold nanocrystallites from 36 to 56 nm dependin...
Fundamentals of light-induced surface plasmon-polariton waves are considered and implemented on the example of goniometric setup assembled by the authors. The setup was used for investigation of angular dependent light transmittance, reflectance, and fluorescence in dielectric layer containing chromophores. It is explained how optical characteristi...
Plasmon-coupled fluorescence of rare earth Sm3+ ions doped into the TiO2 film placed on thin gold layer is investigated. It was demonstrated that plasmon waves induced in the gold layer strongly influence rare earth emission. We revealed that each spectral peak of Sm3+ emission can be directionally separated, polarized and enhanced by intensity due...
It is demonstrated that the spectrum, direction and polarization of rare-earth fluorescence can be tailored by embedding the impurity ions into a planar metal–dielectric structure (MDS). The latter was designed by spin coating a rare-earth-doped oxide film (TiO2:Sm3+) onto a gold-covered glass substrate. For spectral–directional investigations of S...
The paper explores the structure and luminescence of sol-gel-derived SnO2:Eu and SnO2:Eu,Sb nanopowders which may be useful as electrically conductive phosphors. The samples were sintered in air at temperatures reaching up to 1400 degrees C. Raman-, SEM-, EDX- and photoluminescence characterization of the samples was carried out. High-temperature a...
Nanoparticulate SnO2 powders doped with europium (0.5 at%) were prepared by using sol-gel method. The samples were sintered in air or argon at temperatures ranging from 600 to 1400 °C. Raman-, SEM- and photoluminescence characterization of the samples was carried out. The heat-treated samples exposed mainly broad emission bands typical of Eu3+ ions...
Composite material based on a TiO2 matrix doped with Sm3+ ions and co-doped with silver was investigated. Samarium ions together with nano- and micro-aggregates of silver were incorporated
into the titanium alkoxide during the sol-gel process. Samarium ions were excited either directly (λ
exc = 488 nm) or through the TiO2 host (λ
exc = 355 nm). It...
The structurization of a high purity niobium from double electron-beam melted cast microstructure to fine-grained microstructure was completed by equal-channel angular pressing by the Bc route up to a Von Mieses strain of 13.8. In addition, for the viscoplastic behavior study as well as nanostructure and properties improving the hard cyclic viscopl...
Composite based on TiO2 host doped with Sm3+ ions and co-doped with silver nanoparticles is proposed as new fluorescent material. The co-doped samples were prepared from titanium alkoxide precursor by sol–gel method adjusted for addition of Sm3+ ions and Ag nanoparticles. Commercial samarium nitrate salt and silver nanopowder (size of primary parti...
Questions
Question (1)
Hi!
So i have implemented the scatterer on a substrate model to AC/DC Module as at the moment we do not have a wave optics module here available. The model in the beginning works just fine, but sometimes if I import a new scatterer geometry or just rotate a scatterer on the substrate I get the following error... Unable to use old solution format - you need to recompute the solution. Wrong number of DOFs in linearization point... Or a very similar cryptic error message, which does not give any info. I have tried to search for a solution in comsol forums and in the help center, but nobody sees to have a solution for it the solution offered in the comsol website does not manage to solve it. It sometimes just randomly disappears (when change the meshing minimally or sometimes clear the previous results or remove/change a nm to m or smth like that or change the solver). Then it randomly works and randomly stops working again. This has been going on now for several months and it is frustrating.... at the moment I work on a 5.2a version. But the similar random error has bugged a lot of people and over several comsol versions.
Any hints and info appreciated!
