The research group Light and Matter is firmly interconnected with Faculty of Mathematics and Physics at the University of Ljubljana and Faculty of Mechanical Engineering, University of Maribor. Members of the group were mentors for diploma theses (27), master's theses (6) and doctoral dissertations (9) on the field of optics and applications of optical methods. Our contribution is very relevant for local development as more than half of our alumni found employment in the industry. We wrote several textbooks and lecture notes for different levels of education. These publications are indispensable in dissemination of knowledge and establishment of Slovenian terminology on the field of optics. Members of the group covered all optical courses on the Faculty of mathematics and physics for first, second and third cycle degrees and thus play a crucial role in education of promising and employable physicists. This is especially relevant as there are several high-tech optical companies in Slovenia. The programme group is strongly involved in training of specialists in optical methods, light scattering, optical spectroscopy and laser design. Along with training of Slovenian students and young researchers, we also hosted and trained several foreign PhD students. One member of the programme group (professor Drevenšek) spent one semester as a visiting professor at the Nankai University in Tianjin, China.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 2185572Members of the research group were coordinators of several international projects and local principal investigators in numerous bilateral projects. We were thus strongly included in the international labour division and simultaneously contributed to the promotion of Slovenia in the scientific circles. Most notable international projects are two COST actions, both chaired by the members of our group. The first action, Composites of Inorganic Nanotubes and Polymers (COINAPO), COST Action No MP 0902, was chaired by professor Irena Drevenšek. This action included parties from 27 participating countries and its main objective was development, characterisation and applications of novel composite materials from inorganic nanotubes and polymers. We also organised a meeting of participating researchers in December 2011. The second action was Self-assembled guanosine structures for molecular electronic devices, COST Action MP0802, chaired by dr. Lea Spindler. This action had 19 participating countries and concentrated on synthesis, theoretical modelling, characterisation and applications of guanosine structures. We organised three meetings/workshops in Slovenia, the chair of the action was a guest editor for a special issue of Journal of Nucleic Acids, and editor of the book Guanine Quartets: Structure and Applications, published by RSC Publishing, London (2013).
D.01 Chairing over/coordinating (international and national) projects
COBISS.SI-ID: 2665828In collaboration with LPKF, Laser & Electronics, d. o. o., Naklo, Slovenia, we developed a new product - a photolithographic system for non-contact microstructuring LDI (laser direct imaging). The system is designed for rapid production of microscopic structures that are widely used in electronics, microfluidics, nanotechnology and bionanotechnology. The LDI employs acousto-optic deflectors for very fast and extremely accurate positioning of a strongly focused ultraviolet laser beam. This enables precise and rapid production of microstructures and is comparable with other state-of-the-art commercially available devices. The LDI system is used also in our laboratory for research of colloidal and biomimetic systems. We manufacture micrometer-sized particles of different shapes that can – if required for the experiment – be magnetic with a high magnetic susceptibility. The development and employment of this system lead to several scientific publications and to a successfully defended doctoral thesis of a young researcher from industry.
F.06 Development of a new product
COBISS.SI-ID: 25297447We have developed a unique system for non-contact measurements of laser-induced temperature profiles in biological tissues using pulsed photothermal radiometry (PPTR), which is the first to involve a spectrally composite mapping matrix. By developing an original reconstruction algorithm and novel non-uniform signal sampling, we have achieved a record-breaking accuracy and spatial resolution, as demonstrated in numerical simulations and systematic measurements in dedicated tissue phantoms. The practical potential of PPTR profiling was verified in several clinically relevant applications. Analysis of interaction of a prototype Nd:YAP laser emitting at 1342 nm with human skin has shown that 50% of the pulse energy gets absorbed in the top 0.36 mm of skin, which is very favorable for nonablative skin rejuvenation. We have also demonstrated viability of the technique for study of laser removal of tattoos and objective guidance of such treatment. We have developed original procedures for individual determination of the highest safe radiant exposure of human skin and for quantitative characterization of mass diffusion and biochemical decomposition of hemoglobin in traumatic hematomas, which should allow determination of the time of injury in forensic medicine. In addition to 5 papers in scientific journals, these achievements were presented in 4 invited talks at international conferences and summer schools, as well as 2 invited talks at foreign universities.
F.09 Development of a new technological process or technology
COBISS.SI-ID: 26499367We developed a dual-frequency pulsed laser in the infrared (IR) range. The output beam with two similar but distinct frequencies is focused into an organic nonlinear crystal, where a third radiation at the difference of the two frequencies is generated (difference-frequency generation, DFG). Our source emits radiation in the terahertz frequency range and operates at room temperature. The novelty of the IR system is generation of both infrared rays in a common laser resonator. Beams from the Nd:YAG (1.06 μm) and Yb:YAG (1.03 μm) crystals are combined and synchronized with a common Q-switch. Coarse synchronization and energy equalization is achieved by the right ratio of the diameters of the two beams. Accurate synchronization is achieved by adjusting the optical pump to the laser crystals. We were the first to use the organic nonlinear crystal OH1 for the DFG into terahertz region. Due to its large nonlinear response, this crystal enables higher efficency DFG. Because the coherence length for 1-μm pumping light is rather short (~50 μm), a stack of several OH1 crystals was used in a quasi-phase matching configuration. Our dual-frequency infrared laser emits 10 ns long pulses with the energy of 1 mJ at repetition 1.5 kHz, which with a THz generator composed of four OH1 crystals generates 1 μW average and 100 mW peak terahertz power. Development of the IR laser and work on the terahertz source was our part of a large international project and significantly contributed to the project's success. We presented the results of our work on five international conferences, the summarising article is in preparation.
F.08 Development and manufacture of a prototype
COBISS.SI-ID: 27579943