George Agapiou - Academia.edu (original) (raw)

Papers by George Agapiou

The inter-operation of satellite and terrestrial backhauling can prove to be an efficient method ... more The inter-operation of satellite and terrestrial backhauling can prove to be an efficient method to satisfy the increased demand in backhauling needs for the next generation of 5G technology. This paper reports the means for undertaking the task to satisfy the high needs of backhauling in terms of throughput. As it is reported this can be achieved by exploiting the concurrent use of millimeter wave wireless systems along with satellites in order to increase the bit rate of the transmitted traffic

Zenodo (CERN European Organization for Nuclear Research), Jul 14, 2017

Proceedings of SPIE, Jan 21, 2012

ABSTRACT A 60GHz wireless over fiber indoor system is proposed and evaluated, using a microwave/o... more ABSTRACT A 60GHz wireless over fiber indoor system is proposed and evaluated, using a microwave/optical/wireless converged analysis. In order to promote a cost-efficient deployment multimode fiber indoor infrastructure is employed, and a photonic integrated patch antenna combined with a LiNbO3 modulator scheme for all-optical frequency up-conversion are studied. Using, a 3Gb/s Orthogonal Frequency Division Multiplexing (OFDM) based IEEE 802.15.3c prestandard, and OM-4 graded index multimode fiber (GI-MMF) transmission of 100m, an acceptable performance, in terms of Error Vector Magnitude (EVM) is calculated for a wireless coverage in the order of 10m. A possible system topology is proposed which apart from fulfilling the wired-wireless and low cost requirements, utilizing a FTTB single mode fiber (SMF) feeding and MMF indoor deployment, is appropriate for future green system scenarios through λ-reuse and photonic integrated antenna scheme without post amplification.

Proceedings of SPIE, Dec 27, 1996

ABSTRACT The development of a novel laser-based seam tracking system for real-time industrial rob... more ABSTRACT The development of a novel laser-based seam tracking system for real-time industrial robot welding applications is presented. The system is based on a infrared diode laser, able to scan perpendicularly the seam joint using a laser scanner. A dedicated CCD camera collects the reflected laser light and the relative distance of the surface points under the sensor, form the sensor itself, is then calculated by simple triangulation techniques. The features of the seam profile such as the joint position and geometry are extracted and measured, with a precision of a some microns. In this paper the main components of the novel laser-based seam tracking system will be presented, as well as preliminary results obtained by our system. The laser-based seam tracking system will be of low cost, simple to use a nd rugged enough to provide trouble-free service in any welding or hostile industrial environment. This system will be the first to be developed and installed in Greece.

IFIP advances in information and communication technology, 2022

Annual Meeting Optical Society of America, 1989

Measurements of mode indices have been used, along with the WKB method, to determine the index pr... more Measurements of mode indices have been used, along with the WKB method, to determine the index profile of partially buried double diffused waveguides. The waveguides were fabricated using the two-step Ag+ exchange process in BK7 glass. This procedure can, with suitable masking, be used in fabricating a variety of optical components. To make devices with predictable characteristics, waveguide parameters such as maximum index change, index profile, effective guide depth must be correlated to the fabrication parameters. To fabricate the guides, the masked substrate is first immersed in a 2% molar solution of AgNO3 in NaNO3 to form deep waveguide regions, and then reimmersed, unmasked, in a 0.25% solution to form partially buried high index regions in a planar, linear-index waveguide.

Optical Society of America Annual Meeting, 1990

Discontinuities formed either by a local change in waveguide depth or by an abrupt change in the ... more Discontinuities formed either by a local change in waveguide depth or by an abrupt change in the effective index of refraction have important effects on the design and operation of optical components in the waveguide. Our work deals with a structure made up of two waveguides with different geometries and material properties that meet at a planar interface. The abrupt discontinuity causes reflection and radiation, and polarization conversion takes place at the discontinuity, leading to mode conversion. Computed values of the power losses and the power converted to a different polarization are presented. Our experimental work involves adjacent double-diffused (deep) and single-diffused (shallow) waveguides made by Ag+- Na+ ion-exchange in BK-7 glass. By using the prism-coupling technique, we have verified the excitation of all guided modes in the double-diffused region when a single mode impinges on the discontinuity. The intensity profiles of the modes excited in the double-diffused region are displayed by an image-processing system. We have shown experimentally that annealing the waveguide suppresses mode conversion and that a given mode will propagate smoothly across the boundary.

IGI Global eBooks, Oct 5, 2010

Zenodo (CERN European Organization for Nuclear Research), Sep 14, 2017

IFIP advances in information and communication technology, 2023

Zenodo (CERN European Organization for Nuclear Research), Jul 14, 2017

IEEE Transactions on Broadcasting, 2019

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications X, 2017

The 5G era is nearly upon us, and poses several challenges for system designers; one important qu... more The 5G era is nearly upon us, and poses several challenges for system designers; one important question is how the (soon to be standardized) mmWave bands of wireless mobile access can coexist harmoniously with optical links in fixed telecom networks. To this end, we present a Radio-over-Fiber (RoF) backhauling concept, interfaced to a 60-GHz indoor femto-cell via a field-installed optical fiber link. We successfully demonstrate generation of a RoF signal up to 1 Gb/s and transmit it optically over 43 km of deployed Single Mode Fiber (SMF), as well as investigate the performance of the 60-GHz access link as a function of distance. The optical link introduces negligible degradation, contrasting the effect of multipath fading in the 60-GHz wireless channel; the latter requires adaptive equalization using offline DSP. The proposed scheme is further validated by demonstration of a 60-GHz Remote Antenna Unit (RAU) concept, handling real traffic from commercial Gigabit Passive Optical Network (GPON) equipment. Proper RAU operation at 1.25 Gb/s is achieved, accommodating true data packets from a Media Converter emitting at 1310 nm through an in-building fiber link. System performance is confirmed through Bit Error Rate (BER) and Error Vector Magnitude (EVM) measurements. EVMs of ~11 and 19% are achieved with BPSK signals, for distances of 1 and 2 m respectively. As standardization of mmWave technologies moves from 5G testbeds to field-trial prototypes, successful demonstration of such 60-GHz wireless access scenarios over a telecom operator’s commercial fiber infrastructure is even more relevant.

ABSTRACT Ph.D. C. M. Verber

Optics & Laser Technology, 1999

The inter-operation of satellite and terrestrial backhauling can prove to be an efficient method ... more The inter-operation of satellite and terrestrial backhauling can prove to be an efficient method to satisfy the increased demand in backhauling needs for the next generation of 5G technology. This paper reports the means for undertaking the task to satisfy the high needs of backhauling in terms of throughput. As it is reported this can be achieved by exploiting the concurrent use of millimeter wave wireless systems along with satellites in order to increase the bit rate of the transmitted traffic

Zenodo (CERN European Organization for Nuclear Research), Jul 14, 2017

Proceedings of SPIE, Jan 21, 2012

ABSTRACT A 60GHz wireless over fiber indoor system is proposed and evaluated, using a microwave/o... more ABSTRACT A 60GHz wireless over fiber indoor system is proposed and evaluated, using a microwave/optical/wireless converged analysis. In order to promote a cost-efficient deployment multimode fiber indoor infrastructure is employed, and a photonic integrated patch antenna combined with a LiNbO3 modulator scheme for all-optical frequency up-conversion are studied. Using, a 3Gb/s Orthogonal Frequency Division Multiplexing (OFDM) based IEEE 802.15.3c prestandard, and OM-4 graded index multimode fiber (GI-MMF) transmission of 100m, an acceptable performance, in terms of Error Vector Magnitude (EVM) is calculated for a wireless coverage in the order of 10m. A possible system topology is proposed which apart from fulfilling the wired-wireless and low cost requirements, utilizing a FTTB single mode fiber (SMF) feeding and MMF indoor deployment, is appropriate for future green system scenarios through λ-reuse and photonic integrated antenna scheme without post amplification.

Proceedings of SPIE, Dec 27, 1996

ABSTRACT The development of a novel laser-based seam tracking system for real-time industrial rob... more ABSTRACT The development of a novel laser-based seam tracking system for real-time industrial robot welding applications is presented. The system is based on a infrared diode laser, able to scan perpendicularly the seam joint using a laser scanner. A dedicated CCD camera collects the reflected laser light and the relative distance of the surface points under the sensor, form the sensor itself, is then calculated by simple triangulation techniques. The features of the seam profile such as the joint position and geometry are extracted and measured, with a precision of a some microns. In this paper the main components of the novel laser-based seam tracking system will be presented, as well as preliminary results obtained by our system. The laser-based seam tracking system will be of low cost, simple to use a nd rugged enough to provide trouble-free service in any welding or hostile industrial environment. This system will be the first to be developed and installed in Greece.

IFIP advances in information and communication technology, 2022

Annual Meeting Optical Society of America, 1989

Measurements of mode indices have been used, along with the WKB method, to determine the index pr... more Measurements of mode indices have been used, along with the WKB method, to determine the index profile of partially buried double diffused waveguides. The waveguides were fabricated using the two-step Ag+ exchange process in BK7 glass. This procedure can, with suitable masking, be used in fabricating a variety of optical components. To make devices with predictable characteristics, waveguide parameters such as maximum index change, index profile, effective guide depth must be correlated to the fabrication parameters. To fabricate the guides, the masked substrate is first immersed in a 2% molar solution of AgNO3 in NaNO3 to form deep waveguide regions, and then reimmersed, unmasked, in a 0.25% solution to form partially buried high index regions in a planar, linear-index waveguide.

Optical Society of America Annual Meeting, 1990

Discontinuities formed either by a local change in waveguide depth or by an abrupt change in the ... more Discontinuities formed either by a local change in waveguide depth or by an abrupt change in the effective index of refraction have important effects on the design and operation of optical components in the waveguide. Our work deals with a structure made up of two waveguides with different geometries and material properties that meet at a planar interface. The abrupt discontinuity causes reflection and radiation, and polarization conversion takes place at the discontinuity, leading to mode conversion. Computed values of the power losses and the power converted to a different polarization are presented. Our experimental work involves adjacent double-diffused (deep) and single-diffused (shallow) waveguides made by Ag+- Na+ ion-exchange in BK-7 glass. By using the prism-coupling technique, we have verified the excitation of all guided modes in the double-diffused region when a single mode impinges on the discontinuity. The intensity profiles of the modes excited in the double-diffused region are displayed by an image-processing system. We have shown experimentally that annealing the waveguide suppresses mode conversion and that a given mode will propagate smoothly across the boundary.

IGI Global eBooks, Oct 5, 2010

Zenodo (CERN European Organization for Nuclear Research), Sep 14, 2017

IFIP advances in information and communication technology, 2023

Zenodo (CERN European Organization for Nuclear Research), Jul 14, 2017

IEEE Transactions on Broadcasting, 2019

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications X, 2017

The 5G era is nearly upon us, and poses several challenges for system designers; one important qu... more The 5G era is nearly upon us, and poses several challenges for system designers; one important question is how the (soon to be standardized) mmWave bands of wireless mobile access can coexist harmoniously with optical links in fixed telecom networks. To this end, we present a Radio-over-Fiber (RoF) backhauling concept, interfaced to a 60-GHz indoor femto-cell via a field-installed optical fiber link. We successfully demonstrate generation of a RoF signal up to 1 Gb/s and transmit it optically over 43 km of deployed Single Mode Fiber (SMF), as well as investigate the performance of the 60-GHz access link as a function of distance. The optical link introduces negligible degradation, contrasting the effect of multipath fading in the 60-GHz wireless channel; the latter requires adaptive equalization using offline DSP. The proposed scheme is further validated by demonstration of a 60-GHz Remote Antenna Unit (RAU) concept, handling real traffic from commercial Gigabit Passive Optical Network (GPON) equipment. Proper RAU operation at 1.25 Gb/s is achieved, accommodating true data packets from a Media Converter emitting at 1310 nm through an in-building fiber link. System performance is confirmed through Bit Error Rate (BER) and Error Vector Magnitude (EVM) measurements. EVMs of ~11 and 19% are achieved with BPSK signals, for distances of 1 and 2 m respectively. As standardization of mmWave technologies moves from 5G testbeds to field-trial prototypes, successful demonstration of such 60-GHz wireless access scenarios over a telecom operator’s commercial fiber infrastructure is even more relevant.

ABSTRACT Ph.D. C. M. Verber

Optics & Laser Technology, 1999