- Ljubljana, Slovenia
Bostjan Batagelj
University of Ljubljana, Faculty of Electrical Engineering, Faculty Member
- Bostjan Batagelj received his Ph.D. from the University of Ljubljana (UL) in 2003 for work on optical-fiber non-linea... moreBostjan Batagelj received his Ph.D. from the University of Ljubljana (UL) in 2003 for work on optical-fiber non-linearity measurements. He is currently an assistant professor at UL. His current research interests are in the areas of next-generation optical access networks, optical-technology-based timing systems and microwave photonics. He has authored or co-authored over 300 publications and is named as an inventor on 10 patents.edit
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This paper describes cases where the new technology of multi-core fibers and passive optical networks is used to solve the problem of a lack of space in duct pipes for a computer local area network (LAN). A solution to the congestion... more
This paper describes cases where the new technology of multi-core fibers and passive optical networks is used to solve the problem of a lack of space in duct pipes for a computer local area network (LAN). A solution to the congestion problems in computer LANs that involves increasing the number of users per single trunk with a passive optical network technology is suggested, together with replacing the standard single-mode optical fibers that have a single core, with novel single-mode optical fiber that has several cores in the same cladding. The expected benefits are an increased data capacity and space saving. In this paper the design and fabrication of multi-core fiber is also addressed for the example of a 7-core fiber that can be easily manufactured using a stack-and-draw procedure.
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The Fabry-Perot semiconductor laser is a simple, low-cost device with a wide spectrum of wavelengths that is nowadays used widely in optical access telecommunications networks. However, due to fiber's chromatic dispersion, the... more
The Fabry-Perot semiconductor laser is a simple, low-cost device with a wide spectrum of wavelengths that is nowadays used widely in optical access telecommunications networks. However, due to fiber's chromatic dispersion, the transmission distance and the bit rate of directly modulated Fabry-Perot laser links are limited. In this paper we demonstrate the possibility of injection locking a Fabry-Perot laser, which significantly improves the frequency response in some areas of the frequency spectrum with respect to an unlocked Fabry-Perot laser. This makes the injection-locked Fabry-Perot laser very suitable for use in wavelength-division-multiplexed passive optical access networks, because in optical communications, low-cost communication light sources are crucial. In this paper we have experimentally investigated the frequency response of an injection-locked Fabry-Perot laser diode up to frequencies of 10 GHz. The results show an improvement in the frequency response and 3-dB bandwidth of the directly modulated, injection-locked, Fabry-Perot, laser diode in comparison with the free-running mode.
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In this paper, various noninterferometric measurement schemes for determination of single-mode optical fiber nonlinear coefficient are reviewed, studied and discussed. All of proposed measurement techniques use one of the Kerr-related... more
In this paper, various noninterferometric measurement schemes for determination of single-mode optical fiber nonlinear coefficient are reviewed, studied and discussed. All of proposed measurement techniques use one of the Kerr-related phenomena, which are self-phase modulation, modulation instability, cross-phase modulation or four-wave mixing. Some of the methods applied to determine the nonlinear coefficient are based on pulsed lasers instead of continuous wave sources. The brief description of each measurement scheme and method is given. This paper focuses on the comparison of different noninterferometric measurement schemes in terms of their construction set-up simplicity, equipment cost, measurement time and field usage. In many of the measurement techniques, presented in this paper, the accurate determination of the input power becomes a critical factor to reduce the measurement uncertainty. Versatility of testing the various types and lengths of fibers is also an important issue in the design of optical devices and systems.
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Space-division multiplexing (SDM) using a multi-core fiber (MCF) is an attractive technology that will greatly enhance the transmission capacity of optical fibers for the future needs of high-capacity optical communications, so... more
Space-division multiplexing (SDM) using a multi-core fiber (MCF) is an attractive technology that will greatly enhance the transmission capacity of optical fibers for the future needs of high-capacity optical communications, so accommodating the increasing amount of data traffic in our information society. This is why MCFs is one of the candidate technologies, if it is properly designed. The optical signal crosstalk appearing between the cores inside the same cladding is critical and this paper uses numerical software, i.e., Fimmwave and Fimmprop, by Photon Design to simulate the crosstalk between the fiber cores. It also provides a description of the basics for designing and manufacturing single-mode MCFs with a conceptual scheme. The main part of the paper describes the process - from the perform-preparation phase to the fiber-drawing process. At the end, general conclusions are drawn as well as the result of a homogeneity test for our initially fabricated seven-core optical fiber.
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Research Interests: Physics, Optics, Antennas, Antennas & Radio Wave Propagation, Antenna Design, and 12 moreMonopulse Radar, Microwave Reflector Antennas, Satellite Tracking, Patch Antennas, Microstrip Patch Antennas, Electrical And Electronic Engineering, Satellite Antennas, Electronics Letters, Antenna Feeds, Axial ratio, Antenna Radiation Pattern, and electromagnetic wave polarisation
In this paper, simple methods to obtain phase shifts and an amplitude regulation using electro-optical technique, with purpose to drive antenna array systems, are presented. This solution comprises true-time delay properties of the optics... more
In this paper, simple methods to obtain phase shifts and an amplitude regulation using electro-optical technique, with purpose to drive antenna array systems, are presented. This solution comprises true-time delay properties of the optics fiber, driven by tuneable lasers. In the following overview, several techniques proposed by different authors are presented. All methods are based on the same idea, which consists on setting the radiofrequency (RF) signal phase and amplitude in the optical domain instead of using radiofrequency techniques. Trough the electro-optical conversion the RF signal is transferred onto an optical carrier, where it can be influenced to achieve the desired result.
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Accurate determination of fiber nonlinearities is important issue in the design of all-optical transport networks. In this paper, the second-order refractive index (n/sub 2/) has been discussed and its measurement techniques overviewed.... more
Accurate determination of fiber nonlinearities is important issue in the design of all-optical transport networks. In this paper, the second-order refractive index (n/sub 2/) has been discussed and its measurement techniques overviewed. The brief description of each measured method is given. This paper focuses on the comparison of different interferometric and non-interferometric measurement schemes in terms of their simplicity and versatility of testing various types of fibers.
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Low-cost optoelectronic devices are the main limiting factor when it comes to scaling the current access networks based on microwave photonics to the capabilities of smart cities. The use of affordable photodiodes could decrease the use... more
Low-cost optoelectronic devices are the main limiting factor when it comes to scaling the current access networks based on microwave photonics to the capabilities of smart cities. The use of affordable photodiodes could decrease the use of microwave photonics, since it is part of each system. In this paper we evaluate the frequency response of a coaxial packaged photodiode. The design of an electric circuit is presented. The results from the vector network analyzer show that the coaxial packaged photodiode makes photodetectors applicable up to 11.5 GHz. In addition, an experimental verification of the photodiode in an optoelectronic oscillator is performed.
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The Slovenian fiber-to-the-home (FTTH) market is an interesting case, since Slovenia has a high level of FTTH deployment, intense infrastructure competition in urban areas and regulated access to FTTH networks. In this paper, the FTTH... more
The Slovenian fiber-to-the-home (FTTH) market is an interesting case, since Slovenia has a high level of FTTH deployment, intense infrastructure competition in urban areas and regulated access to FTTH networks. In this paper, the FTTH access solutions that are implemented in the Slovenian telecommunications market are reviewed. Before the economic crisis, in 2009, the two main Slovenian telecommunications operators started to deploy FTTH networks in a point-to-point (P2P) architecture and connected nearly 50,000 subscribers. After 2009, a growth in the number of connected households was observed due to regulation of the optical access network, the take-up of the home passed built infrastructure before 2009, cable-television operator investments in cities and public-private partnership investments in rural areas. Those investors that appeared after 2009 have also begun to deploy a point-to-multipoint (P2MP) FTTH architecture, intended for users with lower requirements.
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This invited paper provides an overview of the fiber-to-the-home (FTTH) access solutions that are implemented in the Slovenian telecommunications market. The optical network topology used by Slovenian operators is reviewed and the factors... more
This invited paper provides an overview of the fiber-to-the-home (FTTH) access solutions that are implemented in the Slovenian telecommunications market. The optical network topology used by Slovenian operators is reviewed and the factors that have an impact on the investment in optical access networks are analyzed, including the competition, the regulatory authority and the Slovenian government. In the years before the economic crisis, an accelerated deployment of optical access networks and a consequent increase in the number of household optical connections were observed. The two main Slovenian operators are building a FTTH architecture in the form of point-to-point (P2P) solution, while some public-private partnership projects and one cable television operator have begun to use point-to-multi-point (P2MP) solutions. Although the P2P solution can provide a larger bandwidth per customer than the P2MP, it has already been noted that a mixture of P2P and P2MP solutions will be the right future-proof option, also because it allows multiple operators to be active on a single network. While P2P will serve for the more-demanding users, P2MP will be employed for residential users, with lower requirements, but this will still be in line with the European Digital Agenda.
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All-optical network technologies employing wavelength division multiplexing (WDM) will play the major role in constructing large bandwidth networks. Since such networks require not only transmission line capability enhancement, WDM should... more
All-optical network technologies employing wavelength division multiplexing (WDM) will play the major role in constructing large bandwidth networks. Since such networks require not only transmission line capability enhancement, WDM should be utilised in combination with wavelength routing. The function of routing must be implemented for reaching high connectivity and flexibility of optical network. This paper presents a proposal for a
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This paper presents the bringing of optical fibre to domestic users in the Republic of Slovenia. Slovenia has two main Fibre-to-the-Home (FTTH) providers, deploying access network infrastructure based on Point to Point (P2P) fibre links.... more
This paper presents the bringing of optical fibre to domestic users in the Republic of Slovenia. Slovenia has two main Fibre-to-the-Home (FTTH) providers, deploying access network infrastructure based on Point to Point (P2P) fibre links. In recent years, accelerated deployment of the optical access network and the consequent increase in the number of optical household connections has been noted. These
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This paper I present the design theory of the FWM wavelength converter using single-mode optical fiber. The conversion efficiency for far off and around zero-dispersion wavelength of a fiber are discussed and compared. The theoretical... more
This paper I present the design theory of the FWM wavelength converter using single-mode optical fiber. The conversion efficiency for far off and around zero-dispersion wavelength of a fiber are discussed and compared. The theoretical calculations of the conversion efficiency for both cases are made. The numerical results for wavelength conversion around zero-dispersion wavelength are clearly shown in conversion diagrams. In this paper I also address the optimization of conversion efficiency and bandwidth.
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This paper describes a preliminary study of microwave photonic (MWP) filtering approaches for use in optoelectronic oscillators to further improve the critical parameters. MWP filters with a finite impulse response (FIR) can be realized... more
This paper describes a preliminary study of microwave photonic (MWP) filtering approaches for use in optoelectronic oscillators to further improve the critical parameters. MWP filters with a finite impulse response (FIR) can be realized in the optical domain by establishing a multi-path system. This can be achieved in several different ways, of which two are examined in this paper, i.e. the multi-path and multi-source approaches.
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Research Interests: Mathematics, Optoelectronics, IEEE, Optoelectronics and Photonics, Phase Locked Loop, and 10 moreOscillators, Microwave Photonics, Optical physics, Optical fiber, Optoelectronic Oscillators, Phase Noise, Electrical And Electronic Engineering, Phase Noise Measurement, Delay Locked Loop, and Frequency drift
This paper presents an opto-electronic oscillator (OEO) with a regenerative electronic circuit that increases the selectivity of the oscillator's loop. The regenerative circuit works as a multiplier of the bandpass filter's... more
This paper presents an opto-electronic oscillator (OEO) with a regenerative electronic circuit that increases the selectivity of the oscillator's loop. The regenerative circuit works as a multiplier of the bandpass filter's quality factor. This makes it possible to realize very narrow bandwidths and thus increase the side-mode suppression ratio of the OEO. Our measurements show an almost 20-dB increase in the suppression of the side modes at the expense of an increase in the phase noise by approximately 4 dB at a 1-kHz frequency offset.
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An approach to the generation of a radio-frequency signal using a dual longitudinal mode helium-neon (HeNe) gas laser and the optical mixing technique is proposed and demonstrated. Several approaches using lasers and photodetectors with... more
An approach to the generation of a radio-frequency signal using a dual longitudinal mode helium-neon (HeNe) gas laser and the optical mixing technique is proposed and demonstrated. Several approaches using lasers and photodetectors with different characteristics give a detailed insight into the potential and utility of the optical mixing of two optical waves to generate a radio-frequency reference source. A low-phase-noise radio-frequency signal is observed by a signal-source analyzer because the two lasing modes share the same gain medium in the few-centimeters-long cavity and the relative phase irregular shifting fluctuations between the two wavelengths are low. The observed phase noise below −100 dBc/Hz at the offset of 1 kHz from the continuous-wave tone at the central frequency of 723 MHz indicates that the dual-mode-cavity gas laser efficiently suppresses the wavelength fluctuations between the lightwave modes, enabling a stable radio-frequency signal to be generated.
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This paper describes recent progress in measuring single mode optical fiber nonlinear coefficient. A brief description of interferometric and noninterferometric techniques is included as a basis for comparing their relative performance... more
This paper describes recent progress in measuring single mode optical fiber nonlinear coefficient. A brief description of interferometric and noninterferometric techniques is included as a basis for comparing their relative performance and limitations. All of reviewed measurement techniques use one of the Kerr-related phenomena which are self-phase modulation, modulation instability, cross-phase modulation or four-wave mixing. This paper focuses on the
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ABSTRACT An electro-optical system for a RF-clock-distribution with a temperature-drift and a vibration compensation is presented. An added timing jitter of less than 10 fs_RMS and a clock drift of 50 fs_RMS over 26 hours have been... more
ABSTRACT An electro-optical system for a RF-clock-distribution with a temperature-drift and a vibration compensation is presented. An added timing jitter of less than 10 fs_RMS and a clock drift of 50 fs_RMS over 26 hours have been measured. The RF signal is distributed through a transmitter - receiver topology as intensity modulation on a CW laser at 1550 nm. The temperature and the vibration-induced fiber group-delay variations are compensated by adjusting the wavelength of the laser and making use of the fiber chromatic dispersion. The system uses standard commercially available telecommunication optical components.
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This paper presents the implementation of an active fiber optical-delay stabilization system in an optoelectronic oscillator. The primary use of the system is to stabilize optical point-to-point fiber links for synchronization purposes;... more
This paper presents the implementation of an active fiber optical-delay stabilization system in an optoelectronic oscillator. The primary use of the system is to stabilize optical point-to-point fiber links for synchronization purposes; however, the system can also be efficiently used as a stable optical delay line in an opto-electronic oscillator. By using a multipurpose optical delay stabilization system with an opto-electronic oscillator, a frequency drift of 0.02 ppm/K was achieved.
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A novel system for the RF synchronization is presented. It makes use of standard, commercially-available telecommunication optical components. The added timing jitter of 5 fsRMS has been measured on the first experimental tests.
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Multi-applicable, multi-core, optical fiber technology is expected to move from research laboratories to industry in a short time. This transition will be possible only with an optimized, multi-core manufacturing method. In this paper we... more
Multi-applicable, multi-core, optical fiber technology is expected to move from research laboratories to industry in a short time. This transition will be possible only with an optimized, multi-core manufacturing method. In this paper we give a full description of the basics for designing and manufacturing single-mode, multi-core fiber using the stack-and- draw process. The main part of the paper describes the procedure - from the single-mode, preform-preparation phase to the multi-core, fiber-drawing process. A homogeneity test for our initially fabricated, seven-core optical fiber is also presented.
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In this paper, we present the novel two-tone non-linear coefficient meter achieves high peak power using pulsed operation. Both the two-tone generation and the pulse modulation are obtained from a single LiNbO3 modulator, driven by... more
In this paper, we present the novel two-tone non-linear coefficient meter achieves high peak power using pulsed operation. Both the two-tone generation and the pulse modulation are obtained from a single LiNbO3 modulator, driven by standard microwave pulse generator. The obtained two optical signals have inherently the same linear polarisation. The frequency spacing is precisely set by the modulation signal and no adjustment is required during the measurement because there is no wavelength difference drifting. The systematic errors produced by either stimulated Brillouin scattering or the spectral component coincidence are eliminated. The measurement scheme without expensive optical equipment is simple and well applicable to field measurement. It has long-term stability and good measurement repeatability. The introduced measurement scheme is applicable to all currently available fibre types including photonic crystal fibres.
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The next-generation 5G and 6G radio access networks (RANs) require high-purity millimeter-wave (mm-W) signals to improve the spectral efficiency and, consequently, the bit rate. We present a system based on an opto-electronic oscillator... more
The next-generation 5G and 6G radio access networks (RANs) require high-purity millimeter-wave (mm-W) signals to improve the spectral efficiency and, consequently, the bit rate. We present a system based on an opto-electronic oscillator (OEO) to generate the low-phase-noise signal for up- and down-conversion that does not require a local oscillator at the base-station. The proposed system will improve the requirements of next-generation RANs. We review the state of the art and new results from the development of a single-loop OEO in the central-station of a RAN.
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This paper briefly describes different varactor-loaded multi-subpatch microstrip antenna solutions. Different solutions form kind of an evolutionary sequence, illustrating the process of attaining quite complex final antenna design, and... more
This paper briefly describes different varactor-loaded multi-subpatch microstrip antenna solutions. Different solutions form kind of an evolutionary sequence, illustrating the process of attaining quite complex final antenna design, and describing main properties of individual solutions themselves. The final antenna represents completely frequency and polarization reconfigurable antenna, adjustable by means of varactor diodes, biased by DC voltages. The final design was
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ABSTRACT By applying an electrical current to the metal-coated fiber, a relation between the applied power and the delay difference was measured. The temperature coefficient and the rise time exceed those of other optical-fiber delay-line... more
ABSTRACT By applying an electrical current to the metal-coated fiber, a relation between the applied power and the delay difference was measured. The temperature coefficient and the rise time exceed those of other optical-fiber delay-line implementations.
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Simple methods to obtain phase shifts and an amplitude regulation using electro-optical technique, with purpose to drive antenna array systems, are presented. This solution comprises true-time delay properties of the optical fiber, driven... more
Simple methods to obtain phase shifts and an amplitude regulation using electro-optical technique, with purpose to drive antenna array systems, are presented. This solution comprises true-time delay properties of the optical fiber, driven by tunable lasers, in the following overview, several techniques proposed by different authors are presented. All methods are based on the same idea, which consists on setting
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... Current through the Peltier pump is about ±300mA. This circuit enables the velocity of the laser frequency variation of IOGHzJs. PI'lce of the sanipling * I-lea ing t Cooling Fig. 3 - Change of the laser trequency velocity during... more
... Current through the Peltier pump is about ±300mA. This circuit enables the velocity of the laser frequency variation of IOGHzJs. PI'lce of the sanipling * I-lea ing t Cooling Fig. 3 - Change of the laser trequency velocity during heating and coolinig process. ...
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... Patrik Ritosa, Tomaz Korosec, Jure Tratnik, Luka Naglic and Bostjan Batagelj ... Microstrip patch antennas as a basic radiation element allow simple and inexpensive fabrication, good impedance matching and polarization selection. ...
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