Anyagok és rendszerek nagysűrűségű optikai adattároláshoz = Materials and systems for high density optical data storage

A pályázat eredeti célkitűzésének megfelelően a nagysűrűségű optikai adattárolásra alkalmas anyagok és rendszerek kutatása terén értünk el fontos eredményeket. Az anyagok kutatásának területén az Atomfizika Tanszék kutató csoportja elsősorban a nemzetközi partnerek által kifejlesztett polimer minták optikai tárolásra való alkalmazhatóságát vizsgálta. Modelleztük és mértük az anyagok paramétereit és vizsgáltuk az anyagtulajdonságok hatását az optikai tároló rendszerek működésére. A közreműködő SZFKI optikai kristálymintákat készített és tesztelt, majd alkalmazta a mintákat optikai adattárolásra, vizsgálta a hologramok stabilitását és a kiolvasás hibáját. A rendszerek témájában a tanszéki csoport bekapcsolódott két európai konzorcium munkájába főleg a térfogati adattárolók modellezésének területén. A vastag anyagon való diffrakció számítására a térfogati integrál megoldásának új módszerét javasoltuk, melynek alkalmazásával lehetővé válik a térfogati holografikus rendszerek működésének komplett modellezése, beleértve a tárolóanyag viselkedését is. Új eredményeket értünk el az optikai kártyára alapozott, hordozható, kompakt, polarizációs holografikus rendszerek kutatásában is. Az összesen 36 publikációból 11 referált folyóiratcikk, 3 könyvfejezet és négy szabadalom. Az eredményekről összesen 16 rendezvényen, illetve konferencián számoltunk be. A támogatás alatt három PhD ösztöndíjasunk megszerezte a fokozatot és idén februárban beadásra került egy MTA doktori értekezés a témában. | We achieved important results during the research of materials and systems for high density optical data storage. Concerning materials the research group of the department examined data storage capability of polymer layers developed by international partners. We modeled and experimentally tested characteristics of the materials and studied the effect of material properties on the operation of optical data storage systems. The contributor SZFKI prepared and tested optical crystal samples and applied them for optical data storage, studied stability of holograms and the bit-error-rate of hologram reconstruction. In the subject of systems the group of the department has become member of two European consortia with the task of modeling volume holographic systems. For the calculation of diffraction on thick material we proposed a new method that provides a useful tool for modeling complete volume holographic systems including the behavior of the storage material as well. We achieved new results also in the research of compact, portable polarization holographic systems using optical card form medium. From the 36 publications 11 are articles in referred journals, 3 of them are book chapters and four are filed patent applications. We presented our results on 16 conferences. During the project three PhD were defended and this year in February a new application was submitted to the Council of Doctors of HAS for the Doctor of Science degrees

Multimodal Neuroimaging Microtool for Infrared Optical Stimulation, Thermal Measurements and Recording of Neuronal Activity in the Deep Tissue

Infrared neural stimulation (INS) uses pulsed near-infrared light to generate highly controlled temperature transients in neurons, leading them to fire action potentials. Stimulation of the superficial layer of the intact brain has been presented, however, the stimulation of the deep neural tissue has larger potential in view of therapeutic use. To reveal the underlying mechanism of deep tissue stimulation properly, we present the design, the fabrication scheme and functional testing of a novel, multimodal microelectrode for future INS experiments. Three modalities—electrophysiological recording, thermal measurements and infrared waveguiding abil—were integrated based on silicon MEMS technology. Due to the advanced functionalities, a single probe is sufficient to determine safe stimulation parameters in vivo. As far as we know, this is the first multimodal microelectrode designed for INS studies in deep neural tissue. In this paper, the technology and results of chip-scale measurements are presented

Infrared neural stimulation and inhibition using an implantable silicon photonic microdevice

Brain is one of the most temperature sensitive organs. Besides the fundamental role of temperature in cellular metabolism, thermal response of neuronal populations is also significant during the evolution of various neurodegenerative diseases. For such critical environmental factor, thorough mapping of cellular response to variations in temperature is desired in the living brain. So far, limited efforts have been made to create complex devices that are able to modulate temperature, and concurrently record multiple features of the stimulated region. In our work, the in vivo application of a multimodal photonic neural probe is demonstrated. Optical, thermal, and electrophysiological functions are monolithically integrated in a single device. The system facilitates spatial and temporal control of temperature distribution at high precision in the deep brain tissue through an embedded infrared waveguide, while it provides recording of the artefact-free electrical response of individual cells at multiple locations along the probe shaft. Spatial distribution of the optically induced temperature changes is evaluated through in vitro measurements and a validated multi-physical model. The operation of the multimodal microdevice is demonstrated in the rat neocortex and in the hippocampus to increase or suppress firing rate of stimulated neurons in a reversible manner using continuous wave infrared light (λ = 1550 nm). Our approach is envisioned to be a promising candidate as an advanced experimental toolset to reveal thermally evoked responses in the deep neural tissue

Near-field infrared microscopy of nanometer-sized nickel clusters inside single-walled carbon nanotubes

We used scattering-type scanning near-field optical microscopy (s-SNOM) to characterize nickel nanoclusters grown inside single-walled carbon nanotubes (SWCNT). The nanotubes were filled with Ni(II) acetylacetonate and the molecules were transformed into nickel clusters via annealing. The metal clusters give high local contrast enhancement in near-field phase maps caused by the excitation of free charge carriers. The near-field contrast was simulated using the finite dipole model, approximating the clusters with elliptical nanoparticles. Compared to magnetic force microscopy, s-SNOM appears much more sensitive to localize metal clusters inside carbon nanotubes. We estimate the detection threshold to be ~600 Ni atoms.Comment: 8 pages, 7 figure

Near-field infrared microscopy of nanometer-sized nickel clusters inside single-walled carbon nanotubes

Nickel nanoclusters grown inside single-walled carbon nanotubes (SWCNT) were studied by infrared scattering-type scanning near-field optical microscopy (s-SNOM). The metal clusters give high local contrast enhancement in near-field phase maps caused by the excitation of free charge carriers. The experimental results are supported by calculations using the finite dipole model, approximating the clusters with elliptical nanoparticles. Compared to magnetic force microscopy, s-SNOM appears much more sensitive to detect metal clusters inside carbon nanotubes. We estimate that these clusters contain fewer than ~ 700 Ni atoms