Hybrid Event

Event program

Friday, 5/24/2024 8:30 AM - 12:15 PM, Bellavista, Grand hotel Adriatic, Opatija 8:30 AM - 9:00 AM Opening Ceremony  9:00 AM - 10:00 AM Invited Lectures  1. Bojan Resan (University of Applied Sciences and Arts Northwestern Switzerland, Windisch, Switzerland) Ultrafast Biophotonics   2. M. Jošt, Ž. Ajdič, G. Matič, B. Glažar, M. Jankovec (Faculty of Electrical Engineering, Ljubljana, Slovenia), S. Albrecht (Helmholtz-Zentrum Berlin, Germany), M. Topič (Faculty of Electrical Engineering, Ljubljana, Slovenia) Progress and Challenges in Perovskite Photovoltaics   10:00 AM - 12:15 PM Papers  1. M. Tomić (Institute of Technical Sciences of SASA, Belgrade, Serbia), R. Pavelka (ENT specialist, Wiener Neustadt, Austria), G. Sprinzl ( University Hospital St. Pölten, St. Pölten, Austria), H. Traxler (Medical University of Vienna, Department of Anatomy, Centre for Anatomy and Cell Biology, Vienna, Austria), Z. Djinovic (ACMIT Gmbh, Wiener Neustadt, Austria) Optimized Algorithm for Quasi-Quadrature Interferometric Signal Processing in Totally Implantable Hearing Aids  A new algorithm for processing of quasi-quadrature interferometric signals in optical sensors of incus vibration, based on a 3x3 single-mode fiber optical coupler and low current VCSEL, is presented. This sensor serves as a microphone in the totally implantable hearing aid device. The amplitude of incus vibration spans over a large dynamic range, from a few picometers to a few nanometers, corresponding to sound pressure levels of 30-120 dB, superimposed on slow and hundreds micron large movement of the incus, which is induced by atmospheric pressure changes and the patient physiological activities. Instead of the usual interferometric phase demodulation based on arctangent function, which is processor time and power-consuming, we propose a simple, fast, but accurate technique. In this approach, the low-frequency components of the raw quasi-quadrature signals are used to determine the octant in which the photodetector signals are located and the audio-frequency component of one or another photodetector signal is forwarded to the output, after a simple processing. Two 16-bit ADCs, a DC restoration circuit for each of the interferometric channels and one 16-bit DAC are employed. The sampling rate was 16 kS/s and an ultra-low power 16-bit fixed-point microcontroller performed the signal processing. 2. F. Guzzi, G. Kourousias, R. Pugliese, A. Gianoncelli, F. Billè (Elettra Sincrotrone Trieste S.C.p.A, Basovizza, Italy) Translating and Optimising Computational Microscopy Algorithms with Large Language Models  Numerical simulation algorithms for optics de sign, computational imaging and wave-matter interaction are often implemented in legacy or non-free languages such as Fortran77/90, C/C++ or Matlab. Even if effective, these old codebases may pose challenges for hardware acceleration and parallelization of existing algorithms, two key aspects of modern digital twinning. In this paper, we propose to use Large Language Models (LLMs) to assist in the develop ment, translation and optimization of such algorithms. By testing different free off-the-shelf alternatives, we evaluate our approach on several numerical simulation tasks in computational microscopy. 3. N. Hanine, A. Mannetta, A. Buzzin, V. Ferrara, R. Asquini (Sapienza university of Rome, Rome, Italy) Development of a Through-Glass Programmable Optical Interferometer made of Liquid Crystal Tilted Gratings  This work introduces a novel programmable optical device based on electrically-tunable tilted liquidcrystal gratings (TLCG), obtained on two stacked BK7 glasses, covering a total footprint of a few mm2 . The primary light path follows a straight optical channel made on the upper surface of the bottom glass through double ion exchange method. The application of a voltage between the indium tin oxide (ITO) contacts patterned on the BK7 inner surfaces enables a secondary path since tilted gratings form in liquid crystal wells. Therefore, light is redirected through the top glass and coupled to two parallel optical channels, forming a multilayer Mach-Zehnder Interferometer (MZI) pattern. Finite-Difference Time-Domain (FDTD) simulations at 1550 nm wavelength confirm the light’s routing through the MZI secondary path. A highly-focused light beam is steered out of the plane when the designed TLCG structures, placed on top of the primary path, are electrically activated. Furthermore, the optical coupling of an out-of-plane light beam coming from underneath to the upper MZI arms is successfully proven using glass-etched tilted grating structures. These findings mark promising foundations in developing a simple, cost-effective, versatile, compact and programmable MachZehnder interferometer suitable for optical biosensing and optical communications systems. 4. A. Mannetta (La Sapienza, Univesity of Rome, Rome, Italy), N. Hanine, A. Buzzin, V. Ferrara, R. Asquini (La Sapienza, University of Rome, Rome, Italy) Enhanced Scattering Induced Fluorescence through Gold Nanoarrays and Zinc Oxide Thin Films  This work presents an optical analysis of zinc oxide (ZnO) thin-films employed as a sensitivity enhancer inside photonic biosensing devices. An array of gold nanocylinders is placed onto a SU-8 polymer waveguide, on a BK7 glass substrate. The system is immersed in water and is used to exploit scattering-induced fluorescence to find microcontaminants in aqueous solutions. The assessment was carried out with a 450 nm light excitation because of its compatibility with a wide range of fluorophores. ZnO thin films were implemented as buffer layers at various thicknesses. Results show how the waveguide-array coupling efficiency and the light scattering out of the array plane is greatly improved by implementing ZnO buffer layers: 4 to 8 fold increases are reached, with peaks when the ZnO layer thickness equals 225 nm. In addition, a far-field analysis shows how the ZnO presence doesn’t affect the collimation and the diffraction angle of the projected beam, suggesting its implementation also for light-routing applications. Such results serve as promising support for the use of ZnO thin films as buffer layers in the field of high-performance scattering-induced fluorescence for health, food, environment monitoring and telecommunication devices. 5. I. Čurkovič, B. Kmet, J. Kovač, H. Uršič, D. Kuscer (Jožef Stefan Institute, Ljubljana, Slovenia) Indium-zinc oxide thin films prepared from solutions  Indium oxide and zinc oxide -based semiconductors offer both high electrical conductivity and optical transparency, making them ideal for creating transparent electronic devices on glass. In this study, we used spin-coating and inkjet printing methods to fabricate thin films of indium zinc oxide (IZO) with a Zn/(Zn+In) ratio of 0.36 on glass. The deposition solutions were prepared by dissolving indium nitrate hydrate and zinc acetate dihydrate in alcohole-based solvents. These solutions remained transparent and stable for over a month. The solutions were then deposited on glass, dried, and annealed at elevated temperatures in air, followed by annealing in a reduced atmosphere. The resulting IZO films were 100-nm thick, defect-free, with a small grain size of a few nanometers. They show an optical transmittance greater than 85% in the visible range and a specific electrical resistivity of less than 1 Ωcm. Furthermore, when the films were heated in a reduced atmosphere, their resistivity significantly decreased to approximately 0.005 Ωcm, with no changes observed in their microstructure and optical properties. We will compare and discuss the properties of IZO thin films prepared using both spin coating and inkjet printing methods. 6. A. Alaeddini, A. Buzzin, R. Asquini, D. Caputo, G. de Cesare (Sapienza University of Rome, Rome, Italy) Sub-ppm Evanescent Waveguide Sensor for Heavy Metal Detection in Water  We present an assessment of the performance of a lab-on-chip optoelectronic device consisting of a polymeric waveguide and a hydrogenated amorphous silicon (a-Si:H) photodetector, both integrated on a compact BK7 glass substrate of a few cm2 in surface area. The system detects the concentration of an analyte in a sample by sensing the light power drop at the interaction place between the solution droplet and the guided radiation. The power variation is related to changes in certain optical properties of the sample (i.e. refractive index) and is measured by an a-Si:H photosensor. Solutions of copper (Cu) and mercury (Hg) were modeled in numerical simulations by using an excitation light in the red spectrum (632 nm). The sample-chip interaction is inspected for different parameters and its outcomes are combined with the a-Si:H detector’s experimentally-obtained performance. The reported sensitivity of the sensor reaches up to 25 pA/ppm for Cu and 17 pA/ppm for Hg. Additionally, limits of detection of 6 ppb for Cu and 9 ppb for Hg were achieved. Preliminary results seem very promising for applications related to health and environment monitoring, such as in-situ detection of heavy metals in water by such extremely compact, inexpensive and easy-to-use chip. 7. A. Nawaz, A. Cian, L. Ferrario, A. Picciotto (Bruno Kessler Foundation, Trento, Italy) Influence of Chamber Conditioning on SiO2 Etch Rate and Selectivity, and a Method to Obtain Batch-Level Stability in Etching Performance  Polymerizing dry etching chemistries are particularly sensitive to chamber conditioning, a process aimed at adequately heating the chamber so that the undesirable contamination of chamber walls with fluorocarbon polymer is minimized and thus a better control over etch rate and selectivity is obtained. In this study, we optimize the chamber conditioning process for SiO2 etching with a narrow mask opening (≤ 1.5 µm) and underlying highly-doped silicon layers, serving as contacts in various silicon-based devices. Using an inductively coupled plasma reactive ion etcher (ICP-RIE), integrated with an optical emission spectroscopy (OES) tool, we employ a C4F8-H2-based etching chemistry. Our findings reveal that the main parameter affected by chamber conditioning time is the silicon etch rate. Extended conditioning, using a specific cycling method, is crucial to stabilize the silicon etch rate during the actual process (usually consisting of 25 wafers). Insufficient conditioning time results in significant differences in silicon recess depth between the first and last wafers due to temperature variations in chamber walls. By monitoring key OES peaks during conditioning, we propose a simple method to determine the optimal moment to initiate the process, ensuring a stable silicon etch rate throughout processing, and thus achieve batch-level stability in etching performance. Friday, 5/24/2024 2:30 PM - 5:00 PM, Bellavista, Grand hotel Adriatic, Opatija 2:30 PM - 5:00 PM Papers  1. M. Jagnjić, J. Vuković, B. Skendrović, J. Lončar (Faculty of Electrical Engineering and Computing, University of Zagreb, Zagreb, Croatia), M. Lončarić (Ruđer Bošković Institute, Division of experimental physics, Laboratory for photonics and quantum opt, Zagreb, Croatia), D. Babić (Faculty of Electrical Engineering and Computing, University of Zagreb, Zagreb, Croatia) Optical Ground Station Proposal for Croatian Quantum Communication Infrastructure  The development of quantum computers, which could potentially implement Shor's algorithm and thereby pose a threat to classical encryption, has created the need for establishing ultra-secure communication systems. One solution is quantum key distribution (QKD), a method that theoretically prevents third-party attacks - including quantum computers - due to the fundamental principles of quantum mechanics. While classical optical communication systems allow signal amplification, the no-cloning theorem from the foundations of quantum mechanics prohibits the cloning of unknown photon states. This no-go theorem results in the practical limitation of quantum key distribution via optical fibers, prompting the need for free-space solutions, such as quantum key distribution through satellite links. In this work, we present the proposed design of the first Optical Ground Station connected to the terrestrial Croatian Quantum Communication Infrastructure through a QKD node and optical fibers. The station's function involves receiving prepare-and-measure photons from the European quantum-communications satellite in low Earth orbit and quantum key generation through the decoy-state BB84 protocol. By utilizing the satellite as a trusted node, this process ensures ultra-secure communication between two optical ground stations within the European quantum communication infrastructure. 2. D. Milovancev, N. Vokic (AIT Austrian Institute of Technology, Vienna, Austria) Monolithically Integrated Ultra-Low Noise Balanced Receiver for CV-QKD  In this work we explore monolithic opto-electronic integration platform for significant down-scaling of input-referred noise in custom designed low-noise analog front-end used for balanced photodetection.The perormance of such monolithically integrated approach is compared to a geterogeneously integrated solutions designed in the same technology which require wire-bonding to balanced photodetectors. The designed circuits are targeting bandwidths above 1 GHz. The improved noise performance is leveraged against increased secure key rates and achievable reach in continuous-variable quantum key distribution (CV-QKD) transmission. 3. S. Špoljar, A. Cerović, M. Stipčević (Institut Ruđer Bošković, Zagreb, Croatia) Near Infrared Devices and Protocols for Short Distance Quantum Key Distribution via Telecom Fibers  Quantum computers threaten current secure communication methods, prompting the emergence of new ideas to ensure communication resistant to this threat. Quantum Key Distribution (QKD) is one such technology leveraging quantum physics for secure symmetric key dis tribution. We, therefore, present an experimental setup with accompanying programs for initialization, calibration, and data processing designed for implementing QKD based on the BB84 protocol, using lasers at wavelengths of 810 nm. In our approach, Alice and Bob do not need to have synchronized watches nor share a synchronizing signal: their alignment in time is achieved by minimization of the bit error rate (BER). The protocol has been successfully executed at up to 8.3 dB loss, equivalent to 2.7 km of G.652.D telecom fiber, commonly used in current communications. Achieved BER is 1.0% at 0.7 dB loss and rises to 1.7% for 8.3 dB loss. While usual QKD solutions prefer expensive IR components and detectors in the telecom wavelength range, our study shows the viability of using affordable near-infrared (NIR) optics and silicon SPAD-based detectors for shorter distances. 4. A. Weiss (Joanneum Research, Pinkafeld, Austria), G. Mohr (Joanneum Research, Weiz, Austria), A. Kröpfl, Z. Salem (Joanneum Research, Pinkafeld, Austria) Enabling Unique Photonic Markers for Visible Light Sensing  Backscattered Visible Light Sensing (BVLS) has proven to be a viable solution approach for various applications ranging from occupancy estimation to gesture recognition. When solely capturing reflections, the scope of applications of such systems can be significantly expanded through utilizing distinct photonic materials as markers. A markers’ key requirement is that it can be distinguished from the reflections of the surroundings with unique optical properties in the intensity and/or in the spectrum of reflected light, whereas achieving generally valid unique properties is challenging. In this manuscript, we present an approach for utilizing phosphorescent markers in BVLS. Based on measuring the decay time after a light stimulus, the marker is clearly distinguishable from optical reflections of the surroundings. Importantly, a human observer recognizes neither the light stimulus nor the measuring of the decay time since both are above the perception threshold of the human eye. Our comprehensive real world experiments with Ruthenium and Platinum based markers show that unique marker identification is achieved, including the differentiation between Ruthenium and Platinum markers, up to 50 cm distance between the Sender/Receiver and the marker. The results substantiate that phosphorescent markers in combination with BVLS have the potential for further advancements and applications. 5. V. Cegledi, D. Babić (University of Zagreb Faculty of Electrical Engineering and Computing, Zagreb, Croatia) Correlating Electricity Consumption and Public Illumination from Low Earth Orbit  Artificial lighting is indispensable in the mod ern world. This work investigates the correlation between publicly available measurements of light emitted from the Earth’s surface from LEO with the publicly available energy consumption per country globally with the goal to assess the electrical energy use. To this end, we define a radiometric power conversion coefficient α as a ratio of the light intensity emitted to space to the total energy consumption. Both of these quantities and related parameters are obtained from publicly available sources. 6. D. Babic, J. Tutavac, J. Lončar, J. Vuković (Department of Communication and Space Technologies, University of Zagreb Faculty of Electrical Engi, Zagreb, Croatia) Optical Filter Selection for the Detection of Light Pollution from Low Earth Orbit  Light pollution is defined as excessive, misdirected, or obtrusive artificially produced outdoor lighting. It disrupts ecosystems and wastes energy, besides interfering with astronomic research. Light pollution is currently growing at a rate of almost 10% annually, and is an active area of research and monitoring. This paper describes a design step in the development of a single-pixel monitoring payload to perform light-source identification from low-Earth orbit. Public light sources emit signature light spectra in the visible and near-infrared range. This spectrum is captured in eight or fewer spectral segments using optical bandpass filters thus achieving two orders of magnitude data reduction relative to state-of-the-art mini spectrometers. The challenge is to select the center wavelengths and full width at half maximum (FWHM) of the optical filters to achieve highest accuracy in identifying the light sources in the light mixtures captured from a low Earth orbit (LEO). We describe the optimization procedure used to select filter characteristics for monitoring light pollution from orbit using an eight-detector characterization payload. 7. Z. Djinović (ACMIT Gmbh, Wiener Neustadt, Austria), A. Gavrilović-Wohlmuther (Schoeller-Bleckmann Nitec GmbH, Ternitz, Austria), M. Tomić (Institute of Technical Sciences of SASA, Belgrade, Austria) A Fiber-Optic Technique for the Wall Thickness Measurement of the Industrial Tubes under Harsh Environment  In industrial tubes used in harsh environments like high pressure or temperature in heat exchangers, the issue of wall thinning due to flow accelerated corrosion can end in structural failure. The conventional method for the wall-thickness (WT) monitoring is offline, involving non-destructive testing (NDT) of the tubes, only when the plant is shutdown. Currently, there is no NDT technique available on the market for online WT measurement, primarily due to challenges posed by high-temperature, high-pressure, steam atmosphere, or confined spaces. We propose a sensor system capable of overcoming these limitations associated with common NDT techniques. It is a high-coherence Michelson interferometer based on a 3x3 single-mode fiber optic coupler. The sensing element is a fiber-optic coil firmly attached to the subject tube. Permanent material loss alters the resonant frequency and stiffness of the tube, leading to a change in strain across the wall. The resonant frequency is calculated through FFT analysis of the strain signals acquired by the optoelectronic unit. The wall-thickness is determined from the resonant frequency of the tube. Experimental trials were conducted in laboratory on stainless-steel tubes with different lengths, outside diameters, and wall-thicknesses, by subjecting the tubes to vibrations induced by a shaker, or hammer impact. 8. D. Palaić, N. Lopac, I. Jurdana, D. Brdar (Faculty of Maritime Studies, Rijeka, Croatia) Advancements and Challenges in Underwater Wireless Optical Communication in the Marine Environment  Underwater wireless communication represents an important field for various applications such as oceanographic data collection, environmental monitoring, and the operation of autonomous underwater vehicles. The transmission of information through the marine environment can be done by techniques based on acoustic, radio frequency (RF), and optical waves, with each technique having its advantages and limitations, which are explored in detail in this paper. This paper focuses primarily on optical communication, which is based on the transmission of light in the visible and near-visible spectrum through water. This type of communication offers significant advantages over acoustic and RF methods, primarily in terms of high data rates and lower latency, which are essential for real-time applications. However, optical communication also faces unique challenges, including light absorption and scattering, which can significantly degrade signal quality and limit the effective range of communication. This paper covers the theoretical foundations of optical communication and explains its principles, methods, and the technological advances that have been made in the field. It also discusses the current limitations and challenges of optical communication, such as light attenuation under various undersea conditions and the difficulties in aligning and maintaining stable communication links. Despite these challenges, optical communication remains a promising avenue for high-speed communication in marine environments, with ongoing research focusing on enhancing its robustness and range.

Basic information:

Vera Gradišnik (Croatia), Irena Jurdana (Croatia), Marin Karuza (Croatia), Mario Stipčević (Croatia)

Andrea Aiello (Germany), Domenico Caputo (Italy), Duško Čakara (Croatia), Andreja Gajović (Croatia), Nenad Kralj (Denmark), Danjela Kuščer (Slovenia)

Andrea Aiello (Germany), Domenico Caputo (Italy), Duško Čakara (Croatia), Andreja Gajović (Croatia), Vera Gradišnik (Croatia), Irena Jurdana (Croatia), Marin Karuza (Croatia), Nenad Kralj (Denmark), Danjela Kuščer (Slovenia), Mario Rakić (Croatia), Mario Stipčević (Croatia)

 Registration / Fees:

The discount doesn't apply to PhD students.

NOTE FOR AUTHORS: In order to have your paper published, it is required that you pay at least one registration fee for each paper. Authors of 2 or more papers are entitled to a 10% discount.

Vera Gradišnik
University of Rijeka
Faculty of Engineering
Vukovarska 58
HR-51000 Rijeka, Croatia

e-mail: Vera.Gradisnik@uniri.hr
Phone: +385 51 651557

The best papers will get a special award.
Accepted papers will be published in the ISSN registered conference proceedings. Papers presented at the conference will be submitted for inclusion in the IEEE Xplore Digital Library.
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There is a possibility that the selected scientific papers with some further modification and refinement are being published in the following journals: Journal of Computing and Information Technology (CIT), MDPI Applied Science, MDPI Information Journal, Frontiers and EAI Endorsed Transaction on Scalable Information Systems.

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