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MIPRO 2021 - 44th International Convention

OPHO - Optoelectronics and Photonics

Wednesday, 9/29/2021 4:00 PM - 7:00 PM, Bellavista, Grand hotel Adriatic, Opatija

Hybrid Event

Special session OPHO is an integral part of the conference Microelectronics, Electronics and Electronic Technology /MEET.

Event program
Wednesday, 9/29/2021 4:00 PM - 7:00 PM,
Bellavista, Grand hotel Adriatic, Opatija
4:00 PM - 4:05 PM Chairmen's Foreword and Introduction of Participants 
4:05 PM - 4:30 PM Invited Lecture 
Matej Peranić, Martin Lončarić, Anton Radman, Mario Stipčević (Ruđer Bošković Institute, Zagreb, Croatia)
Quantum Communication with Entangled Photon Pairs 
4:30 PM - 6:55 PM Papers 
1.J. Tutavac, D. Babić (Faculty of Electrical Engineering and Computing, Zagreb, Croatia)
Spectral Unmixing of Light-Emitting Diode and High-Intensity Discharge Illumination Sources 
In the recent decades, high-intensity discharge lamps, installed for public illumination, are gradually being replaced with solid-state lighting (white light-emitting diodes). This is resulting in markedly better energy efficiency, but is also raising environmental concerns related to the extra blue light emitted. Using a CubeSat, we plan to track the global progress of solid-state lighting and its contribution to light pollution. Inasmuch as the light emitted from the Earth is a mixture of a wide variety of light sources, estimating the contribution of any individual source is a challenging task referred to as spectral unmixing. In this work, we present a method for spectral unmixing of light mixtures created by a multiplicity of conventional sources, including high-intensity discharge lamps and light-emitting diodes, as measured by a spectrophotometer. We demonstrate unmixing of light into two constituent spectra, one of which is the solidstate lighting spectra, using a non-negative constrained leastsquares method with final accuracy of 93%. We furthermore show that the proposed method can be used when the mixture is captured using less than ten filtered detectors rather than a several-thousand-channel spectrometer, which is the most likely implementation on our satellite. All of our experiments have been done in a laboratory.
2.A. Kuttner, M. Hauser, A. Dervic, H. Zimmermann, M. Hofbauer (TU Wien - Institute of Electrodynamics, Microwave and Circuit Engineering, Vienna, Austria)
SPAD Based Digital Photon Counting Optical Distance Sensor in 150 nm CMOS Using Indirect Multiphase Time-of-Flight 
In this work a single photon avalanche diode (SPAD) based phase measurement circuit for distance measurements using continuously modulated light in a 150 nm CMOS technology is presented. An on-chip quadruple-voltage quenching circuit, allowing up to 7.2 V excess bias for external SPADs, generates pulses synchronous to the detection times of single photons. Circuit simulations show, that a precision of 0.54 mm can be achieved for distance measurements in low background light environments, in a measurement time of 200 μs. The efficiency of background light suppression can be improved by increasing the measurement time. Even a factor of 100:1 of background to measurement light should allow sub-cm precision given a sufficient measurement time. Correlation frequencies up to 1 GHz are possible. One correlator block has a size of 230×210 μm² and the power consumption for each correlator is 391 μW.
3.M. Hauser, A. Dervic, A. Kuttner, H. Zimmermann, M. Hofbauer (TU Wien, Vienna, Austria)
Time of Flight Analog Correlator for Distance Measurement with SPADs 
An analog time of flight correlator designed in a 150 nm LFoundry CMOS process, capable of correlating photon pulses with an input clock for the use with single-photon avalanche diodes (SPADs) is presented. This correlator will allow highly sensitive and high precision indirect time of flight (iTOF) distance measurement with modulation frequencies up to 1 GHz and a distance resolution of 3 mm for a total correlation time of only 4 µs. However, due to the high dynamic range long correlation times are also possible, which guarantee operation with high background-to-signal-ratios (BSR). The small size and low power consumption of less than 1 mW allow the use of many correlators on a single chip. Two correlators and a quenching circuit are integrated on a chip with a size of 1.5 × 1.3 mm² and the size of a single correlator is 225 × 143 µm².
4.M. Karuza (University of Rijeka, Department of Physics, Rijeka, Croatia), M. Čanađija (Faculty of Engineering, Rijeka, Croatia), M. Markanović, I. Jelovica Badovinac, K. Veličan (University of Rijeka, Department of Physics, Rijeka, Croatia), D. Božičević (Faculty of Engineering, Rijeka, Croatia), M. Vretenar (University of Twente, Faculty of Science and Technology, Enschede, Netherlands), D. Čakara (University of Rijeka, Department of Biotehnology, Rijeka, Croatia), G. Cantatore (INFN Sezione di Trieste and University of Trieste, Trieste, Italy)
Advances in Optomechanical Force Sensors 
Mechanical elements are successfully employed as force sensors in various devices. The sensors have reached impressive sensitivity of few nN/sqrt(Hz), but the quest for even more sensitive sensors is still on. The capability of sensing a single bacteria stuck to the sensor's surface in few seconds would provide unprecedented possibilities in various fields. Even in physics such sensitive sensors could be used in search for the elusive constituents of the dark sector. A possible interaction of either dark energy or dark matter with the sensor could be detected. A characterisation of an optimised sensor element will be presented along with it's properties.
5.F. Guzzi (University Of Trieste, Trieste, Italy), G. Kourousias, F. Billè, R. Pugliese, A. Gianoncelli (Elettra Sincrotrone Trieste, Trieste, Italy), S. Carrato (University of Trieste, Trieste, Italy)
A Deep Prior Method for Fourier Ptychography Microscopy 
Fourier Ptychography is an emerging microscope technique which is increasingly used for biological samples of high importance. The technique allows for stunning resolution without having to cope with a restricted field of view. This result is achieved by combining phase retrieval with an aperture synthesis procedure, indeed casting the technique as one of the most advanced computational imaging investigation methods. Due to the nature of the inverse problem involved (phase retrieval), currently, only iterative algorithms can be employed for reconstruction, thus delaying the image visualisation from the acquisition process. In this paper, we propose a deep learning method to seed the iterative reconstruction and obtain a higher quality result in less time. A parameter agnostic CNN is trained to produce an initial estimate for the iterative process. The final reconstructions exhibit a reduced amount of artefacts, even for a limited illumination Numerical Aperture. Our method is decisive to relax the design of the illumination array.
6.Z. Djinovic (ACMIT Gmbh, Wiener Neustadt, Austria), M. Tomic (Institute of Technical Sciences of SASA, Belgrade, Serbia), N. Plank (ACMIT Gmbh, Wiener Neustadt, Austria)
A Fiber-optic Sensing Technique for Sub-micrometer Distance Measurement between the Surgical Tools and Retina 
Many retina diseases require very often a delicate surgical intervention, which is performed by different minimally invasive instruments and tools. They must be miniature but still robust and capable to accurately determine the separation to the retina target in real time. Because of that they have to be instrumented with a sensing technique, which may interactively read the actual distance toward the target without any risk of injuring the retina. In this paper we present a fiber-optic sensing technique suitable for integration into the surgical instruments. The technique is composed of low- and high-coherence interferometry that allows sub-micrometer absolute distance measurement between the surgical tools and retina without any scanning unit in the reference arm. The technique is demonstrated utilizing the experimental setup based on a 2x2 fiber-optic coupler simultaneously powered by an SLD and VCSEL as low- and high-coherence light sources, respectively. The sensing arm was directed toward the eye model, made of inner silicon layer and outer polylactide (PLA) 3D printed eyeball. The distance between the sensing fiber tip and target has been measured using both low-and high-coherence interferograms over a rather large dynamic range of about 2 mm with accuracy of 650 nm that corresponds with λ/2 of the high-coherence light source.
7.A. Buzzin, R. Asquini, D. Caputo, G. de Cesare (Sapienza University of Rome, Rome, Italy)
Optical Detection of Analytes through Evanescent Waves in Lab-on-Chip Devices 
This work presents an optoelectronic, integrated system-on-glass for on-chip, quantitative detection of a specific analyte in a biological solution. The system includes, on a single glass substrate, an amorphous silicon (a-Si:H) photodetector and an optical waveguide. The solution under investigation is placed on a region of the waveguide where a monochromatic light is traveling. The light-solution interaction changes with the sample’s optical properties, with the waveguide’s thickness and with the overlapping area. Two kinds of waveguide have been modeled and tested: glass-made waveguides, obtained by the double ion-exchange method on the glass substrate, and SU-8 polymer waveguides, obtained by photolithography. Measured optical losses are around 0.5 dB/cm at the wavelength of 532 nm. The analyte detection is performed by a thin-film, a-Si:H photosensor, a p-doped/intrinsic/n-doped junction, deposited by Plasma Enhanced Chemical Vapor Deposition and fabricated with microelectronic technologies, with a metal contact on the n-doped side and an indium-tin oxide (ITO) transparent contact on the p-doped side. From electro-optical characterizations, we found that the photodiodes present shot noise currents of about 2 fA/sqrt(Hz) and responsivity around 500 mA/W at 532 nm. Electro-optical coupling tests were performed to validate the systems. As proofs of concept, cholesterol and hemoglobin as analytes were studied for a demonstration scenario, involving optical simulations interpolated with experimental data. The modeled detection limit for hemoglobin concentration in aqueous solution is around 100 ppm, in line with well-established colorimetric methods currently on the market. These results show the effectiveness of the proposed system in biological detection applications and encourage further developments in implementing these kinds of devices in the biomedical field.
8.V. Gradišnik (University of Rijeka, Faculty of Engineering, Rijeka, Croatia), K. Veličan (Department of Physics, University of Rijeka, Rijeka, Croatia), D. Gumbarević (Prirodoslovna i grafička škola Rijeka, Rijeka, Croatia), M. Karuza (Department of Physics, University of Rijeka, Rijeka, Croatia)
Light dependent Temperature Characteristics of a-Si:H p-i-n photodiode 
As a consequence of chemical reactions in specific biological samples thermal energy can be released which influences the response of the transducer of optical label-free biosensors used in lab-on-chip applications. To improve and understand the sensitivity limitations, the transient thermal characteristics of a-Si:H p-i-n photodiode is measured and analysed. We report the results obtained with device operating at different reverse bias voltages (200 mV and 1 V) in the dark and under illumination with blue LED. The behaviour of the sensor was studied at temperatures varying from 303 K to 327 K. The temperature of the sample was actively stabilised by a feedback loop. The variations in the photodiode current and its time dependency are observed. These results might explain the increased sensitivity of the photodiode in previous analysis of biological samples.
6:55 PM - 7:00 PM Future directions and closure of the special session 

Basic information:

Vera Gradišnik (Croatia), Irena Jurdana (Croatia), Marin Karuza (Croatia), Duško Čakara (Croatia)

Registration / Fees:
Price in EUR
Up to 13 September 2021
From 14 September 2021
Members of MIPRO and IEEE 200 230
Students (undergraduate and graduate), primary and secondary school teachers 120 140
Others 220 250

The discount doesn't apply to PhD students.


Vera Gradišnik

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

e-mail: or
Phone: +385 51 651557

The best papers will get a special award.
Accepted papers will be published in the ISSN registered conference proceedings. Presented papers in English will be submitted for inclusion in the IEEE Xplore Digital Library.
There is a possibility that the selected scientific papers with some further modification and refinement are being published in the Journal of Computing and Information Technology (CIT).


Opatija, with its 170-year-old tourism tradition, is the leading seaside resort of the Eastern Adriatic and one of the most famous tourist destinations on the Mediterranean. With its aristocratic architecture and style, Opatija has been attracting artists, kings, politicians, scientists, sportsmen, as well as business people, bankers and managers for more than 170 years.

The tourist offer in Opatija includes a vast number of hotels, excellent restaurants, entertainment venues, art festivals, superb modern and classical music concerts, beaches and swimming pools – this city satisfies all wishes and demands.

Opatija, the Queen of the Adriatic, is also one of the most prominent congress cities in the Mediterranean, particularly important for its ICT conventions, one of which is MIPRO, which has been held in Opatija since 1979, and has attracted more than a thousand participants from over forty countries. These conventions promote Opatija as one of the most desirable technological, business, educational and scientific centers in South-eastern Europe and the European Union in general.

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