Projects / Programmes source: ARIS

Optical microresonators based on liquid crystals

Research activity

Code Science Field Subfield
1.02.01  Natural sciences and mathematics  Physics  Physics of condesed matter 

Code Science Field
P002  Natural sciences and mathematics  Physics 

Code Science Field
1.03  Natural Sciences  Physical sciences 
optical microresonators, photonic integrated circuits, liquid crystals, complex soft matter
Evaluation (rules)
source: COBISS
Researchers (13)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  14080  PhD Denis Arčon  Physics  Researcher  2010 - 2013  594 
2.  33197  PhD Simon Čopar  Physics  Researcher  2011 - 2012  160 
3.  29528  PhD Matjaž Humar  Physics  Researcher  2010 - 2013  184 
4.  32598  PhD Venkata Subba Rao Jampani  Physics  Technical associate  2012 - 2013  53 
5.  03426  MSc Bojan Marin  Physics  Researcher  2012 - 2013  93 
6.  09089  PhD Igor Muševič  Physics  Head  2010 - 2013  750 
7.  33744  PhD Maryam Nikkhou  Physics  Researcher  2012 - 2013  14 
8.  33377  PhD Andriy Nych  Physics  Researcher  2011  48 
9.  33378  PhD Uliana Ognysta  Physics  Researcher  2011  27 
10.  12338  PhD Miha Škarabot  Physics  Researcher  2010 - 2013  253 
11.  26467  PhD Uroš Tkalec  Physics  Researcher  2010 - 2013  213 
12.  22137  Bernarda Urankar  Educational studies  Researcher  2012 - 2013  26 
13.  07110  PhD Slobodan Žumer  Physics  Researcher  2011 - 2013  1,026 
Organisations (2)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  90,600 
2.  1554  University of Ljubljana, Faculty of Mathematics and Physics  Ljubljana  1627007  34,059 
It is generally anticipated that the 21st century will be dominated by photonics and integrated photonic technology because of their importance for global telecommunication systems, based on fiber optics networks and information transfer by light. This project is from the rapidly evolving subfield of integrated photonics, based on complex soft matter and brings an important new paradigm to this subfield. The idea of the project is based on recently discovered electrically tunable optical microresonators made of confined nematic liquid crystals (Humar et al., Nature Photonics 3, 595(2009) and has the goal to assemble an optical transistor, based on tunable nematic microresonator. These are individual small droplets of a nematic liquid crystal, which are formed spontaneously by phase separation from the surrounding polymer. Liquid crystal microresonators have a particular property, that the spectrum of light, confined inside the resonator by total internal reflection at the resonator's wall, can be tuned efficiently by a small external electric field. Electric tuning of these whispering gallery modes (WGM's) can be as large as 20 nm at 2.5 V/micrometer and is nearly two orders of magnitude larger compared to solid state microresonators. Within this proposal, we intend to study the mechanisms of self-alignment of microresonators in the vicinity of planar optical waveguides and understand the nature of resonant light transport from the waveguide to the tunable nematic microresonator.We shall study the spectral properties of nematic microresonators with different internal structures and organization of the liquid crystal, as well as the effects of the external electric and optical fields on the resonance spectra. We intend to study the dynamics of the spectral response for different phases and structures of a liquid crystal and we shall determine the cutoff frequency for mode selection and tuning. We shall study the nature of resonant transport of light in an optical transistor, formed by a liquid crystal microresonator in a close proximity to the planar optical waveguide. Here the light transmission through the waveguide shall be modulated by energy losses due to the resonantly coupled liquid crystal microresonator. We want to explore whether such an optical transistor, based on resonantly coupled microcavities, could be used as a basic element of a future integrated soft matter optical integrated circuit, where the light transport could be controlled either by electric field or light. We also want to study the resonant properties of onion and Bragg resonators, which can be formed spontaneously when cholesteric liquid crystals or Blue phase liquid crystals are used. We shall study stimulated emission and the possibility of lasing in such microresonators with an aim to assemble arrays of micro-lasers and optical micro-amplifiers. We are confident, that a successful realization of the proposed research program would have a deep and profound impact on microphotonic devices of the 21st century and would drive the realization of complex, 3D spatially distributed networks of waveguides and active devices based on confined soft matter.
Significance for science
It is generally accepted in the scientific community, that photonics will be one of the fastest developing scientific disciplines of the 21st century. We have completed an ambitious research project, which is at the cutting edge of today's photonics, colloidal science and liquid crystals that has laid foundations for the new direction in photonics, which may have profound impact in the future. There are several important scientific contributions of this project and among these lat us mention only three most important. We have achieved a substantial breakthrough in the field of colloidal self-assembly in nematic liquid crystals by our discovery of knotting and linking of colloidal particles in chiral nematic ordering field, published in Science in 2011. Besides having a deep fundamental aspect, our work on knots and links is important for application, because knots and links provide a firm mechanical binding of colloidal particles and droplets into thermodynamically stable functional unit, i.e. an integrated soft matter photonic circuit. Our demonstration of an optically pumped dye micro-laser, based on a micro-droplet of a chiral nematic liquid crystal, has attracted huge scientific interest, because it is the first micro-source of coherent and monochromatic light pulses, which is controlled all-optically. The third important result is our demonstration of wave-guiding and lasing in optical micro-fibres made of smectic-A liquid crystal. All these results demonstrate that it is indeed possible to create basic photonic micro-elements based exclusively on different soft matter, i.e. liquid crystals and other immiscible fluids. These photonic elements could be knotted and linked with additional immiscible nematic liquid crystal into firmly bound 3D complex structure, where light could resonantly be transferred between different elements. Successful completion of this project has laid foundations fora novel direction in photonics, named "topological photonics". It is based on self-organized soft matter, where the topology is important and flow of photons is controlled by photons. The results of this project have been published in a large number of articles and have achieved excellent international visibility. For example, Nature Photonics and Optical Society of America have reported on our 3D micro-laser and lasing liquid crystalline fibres.
Significance for the country
Our successfully completed project »Optical Microresonators based on Liquid Crystals« has contributed significantly to the international cooperation of Slovenian scientists in the field of Photonics. Photonics is one of the most rapidly evolving fields of Physics and includes such diverse sub-fields, such as quantum computing, all-optic processing of information to harvesting of light for sustainable development. This project has brought some important contributions not only in the applied area of all-optical processing of information, but also experimental realization of fundamental phenomena of topology. Successful completion of this project has several important contributions for Slovenia: 1. Participation of Slovenian scientists in several international projects, related to photonics. Two research groups, which have completed the project, have participated in 6 international scientific projects: (1) COST D43 Action Colloid and Interface Chemistry for Nanotechnology, members of WG2 "Synthesis and Availability of Reference Materials" (I. Muševič); (2) COST MP 0604, "Optical micromanipulation by nonlinear photonics", I. Muševic, Slovenian representative; (3) FP7 Marie Curie Initial Training Network "Hierarchical Assembly in Controllable Matrices" including 3 partners from Slovenia. (4) NEMCODE- Controlled Assembly and Stabilization of Functionalized Colloids in Nematic Liquid Crystals, Marie Curie post-docproject by Dr. Giorgio Mirri at J.Stefan Institute (2013-2015). (5) LIVINGLASER- A laser made entirely of living cells and materials derived from living organisms, Marie Curie post-doc project by Dr. Matjaž Humar at IJS and General Hospital Corporation, Boston, USA. (6) Bilateral project Slovenia-Ukraine, BI-UA/13-14-007; Blue Phases of Liquid Crystals. 2. We have patented our work on 3D microlasers in an PCT application »Spherical liquid-crystal laser«, which is now in a process of obtaining national patents in several countries of EU, USA, Russia, China, South Korea, Hong Kong, Japan and India. 3. We were invited to give 4 plenary lectures at important international conferences, including "46th Biennial Meeting of the Colloid Society" organized by the University of Paderbornu, "24th International Liquid Crystal Conference" organized by the International Liquid Crystal Society, "8th Liquid Matter Conference" organized by the University of Vienna, "Wetting and Capillarity in Complex Systems" organized by the “Max-Planck Institute fur physik komplexe systeme” and »12th International Symposium on Colloidal and Molecular Electrooptics” organized by the University in Mainzu. 4. We were invited to give 12 invited lectures at international conferences 5. We were invited to give 6 invited lectures at foreign universities, including the University of Oxford, University of Colorado at Boulder, Radboud University, Nijmegen, University of California, Santa Barbara, Univerza La Sapienza, Rim, and Max Planck Institute for Dynamics and Self-Organization, Goettingen, Germany. 6. Three PhD Thesis have been completed within this project, including Dr. Tkalec Uroš, Institut 'Jožef Stefan', Dr. Humar Matjaž, Institut 'Jožef Stefan', and Dr. Venkata Subba Rao Jampani, University of Ljubljani, Faculty of Mathematics and Physics. Successful completion of this project will help in obtaining new projects in the future, the groups are in a process of preparation of the proposal within "Future and Emerging Technologies" of Horizon 2020; in the year 2017, Ljubljana will host the international scientific conference “Liquid Matter 2017”.
Most important scientific results Annual report 2010, 2011, 2012, final report, complete report on dLib.si
Most important socioeconomically and culturally relevant results Annual report 2010, 2011, 2012, final report, complete report on dLib.si
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