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Papers by Ronnie Kritzinger

Research paper thumbnail of Manufacturing of azimuthally symmetric long-period fibre gratings using a CO2 laser

E.1 Comparison of different Optical fibres F Calculation of coupling constants in LPGs 194 F.1 Co... more E.1 Comparison of different Optical fibres F Calculation of coupling constants in LPGs 194 F.1 Coupling constant calculation process F.1.1 Obtaining effective refractive index nrife of the LPoi guided mode F.1.2 Obtaining effective refractive index <II of the specific LPi n, nth cladding mode F.1.3 Simplifying and solving expressions to obtain coupling constants G Flow graph for Simulation programs 205 G.1 Flow graph illustrating the simulation of short-and long-period fibre gratings CONTENTS H Overview of ECODRIVE03 drive controller H.1 Function Overview H.2 Configuration setup for Drive Controller H.3 Communication with ASCII protocol H.3.1 Actuating a Specific Bus User H.3.2 Read accessing a parameter H.3.3 Write accessing a parameter H.3.4 Layout of ECODRIVE03 DKC Drive Controller I Computer Control program 1.1 Introduction 1.1.1 Overview of computer control program J Gaussian Optic Theory J.1 Gaussian Beam Optics J.2 Focussing and Collimating J.3 Optics Formulas J.4 Optics Glossary K SOLIDWORKS drawings of machined plastic blocks K.1 Discussion on the SOLIDWORKS drawings 250 K.

Research paper thumbnail of Design and fabrication of long-period fibre gratings and wavelength-selective couplers for wavelength-division multiplexing networks

Research paper thumbnail of Optical add / drop multiplexer using short-and chirped long-period fibre gratings for dense wavelength-division multiplexing

We propose and demonstrate the use of a novel wavelength-tuneable optical add/drop multiplexer (O... more We propose and demonstrate the use of a novel wavelength-tuneable optical add/drop multiplexer (OADM) device based on fibre Bragg gratings (FBGs) and chirped long-period gratings (CLPGs) having a broad transmission spectrum. Numerical simulations predict bandwidths in the order of 40 nm and higher. Fabrication of the symmetric CLPGs, and the method of strain used for tuning of the fibre Bragg grating are also discussed.

Research paper thumbnail of Motivational factors, customer engagement and loyalty in the South African mobile instant messaging environment: moderating effect of application usage

European Business Review, 2020

Purpose The purpose of this paper is to examine specific gratifications obtained from using mobil... more Purpose The purpose of this paper is to examine specific gratifications obtained from using mobile instant messaging (MIM) applications by applying the uses and gratifications theory. This study explores the relationships between motivational factors, customer engagement and loyalty for existing WhatsApp subscribers in South Africa, as well as the moderating effect of application usage. Design/methodology/approach A descripto-explanatory research design was used in this quantitative study and 282 responses from an online survey were analysed. Structural equation modelling was used to test the study’s hypotheses. Findings The study reveals that utilitarian and hedonic motivation impact customer engagement positively in using WhatsApp, which, in turn, impacts loyalty. Social motivation in using WhatsApp bore no relationship with customer engagement. Furthermore, medium application usage moderates the link between customer engagement and utilitarian and hedonic motivation. Research lim...

Research paper thumbnail of Digital Design of Broadband Long-Period Fibre Gratings by an Inverse Scattering Algorithm with Flip-Flop Optimisation

SAIEE Africa Research Journal, 2012

A discrete inverse scattering method, known as layer-peeling, is used to synthesise a LPFG (long-... more A discrete inverse scattering method, known as layer-peeling, is used to synthesise a LPFG (long-period fibre grating) from a desired complex spectrum by a direct solution of the coupled-mode equations, while simultaneously determining the physical properties of the layered structure. The physical properties of the grating structure are determined in a recursive layer-by-layer manner by using causality arguments to design LPFGs exhibiting a flat-top spectral profile. The results obtained from the layer-peeling method are optimised using the flip-flop method to ease the fabrication process. We found that the layer-peeling method has the highest performance and executes in the least amount of time. A discussion of possible applications where optimised broadband LPFGs could be utilised in the field of telecommunications and sensing demonstrates the importance of the results.

Research paper thumbnail of Supercontinuum generation with a figure-eight fiber laser

Third European Workshop on Optical Fibre Sensors, 2007

ABSTRACT We use a figure-eight fibre laser with a photonic crystal fibre NALM (nonlinear amplifyi... more ABSTRACT We use a figure-eight fibre laser with a photonic crystal fibre NALM (nonlinear amplifying loop mirror) to produce a moderate supercontinuum from 1440 nm - 1680 nm in highly nonlinear dispersion shifted fibre. We also observe a 743 nm band in the fluorescence of the erbium doped amplifier outside the figure-eight fibre laser.

Research paper thumbnail of Design and fabrication of low-loss broadband transmission filters for dense wavelength-division multiplexing networks

AFRICON 2007, 2007

We present a method to design broadband optical transmission filters from complex spectrum profil... more We present a method to design broadband optical transmission filters from complex spectrum profiles, for application in dense wavelength-division multiplexing (DWDM) systems. A discrete inverse scattering method, known as layer-peeling, is used to reconstruct a long-period fibre grating (LPG) structure from a specified realisable complex spectrum by a direct solution of the coupled-mode equations, while simultaneously determining the physical properties

Research paper thumbnail of Wavelength-tuneable add/drop multiplexer using broadband transmission filters and a narrowband reflection filter

SPIE Proceedings, 2008

... Ronnie Kritzinger, André Booysen Centre for Optical Communications and Sensors University of ... more ... Ronnie Kritzinger, André Booysen Centre for Optical Communications and Sensors University of Johannesburg, PO Box 524, Auckland Park ... 19th International Conference on Optical Fibre Sensors, edited by David Sampson, Stephen Collins, Kyunghwan Oh, Ryozo Yamauchi ...

Research paper thumbnail of Investigation of the power coupling of novel wavelength-selective couplers incorporating axially symmetric long-period fibre gratings

South African Journal of Science, 2011

Evanescent-field coupling was studied experimentally in novel optical-fibre-based wavelengthselec... more Evanescent-field coupling was studied experimentally in novel optical-fibre-based wavelengthselective couplers, using axially symmetric long-period fibre grating (LPFG) structures. The coupling characteristics of a wavelength-selective coupler at the resonant wavelength were investigated for different LPFG offset distances. It was shown that the wavelength-selective couplers effectively transferred light power at the LPFG resonant wavelength from one fibre to another. The performance of the couplers was consistent with simulations performed in MATLAB using coupled-mode theory.

Research paper thumbnail of Azimuthally symmetric long-period fibre grating fabrication with a TEM 01∗ -mode CO 2 laser

Measurement Science and Technology, 2009

Research paper thumbnail of Design and Fabrication of Novel Broadband Long-Period Fiber Gratings Using Synthesis Techniques

Journal of Lightwave Technology, 2011

We present results of novel broadband long-period gratings (LPGs) that were fabricated axially sy... more We present results of novel broadband long-period gratings (LPGs) that were fabricated axially symmetric in singlemode fiber with a carbon-dioxide laser. The discrete layer-peeling (DLP) technique and a genetic algorithm (GA) were used to design the LPGs. Numerical simulations were used to indicate the performance and absolute error of reconstructing a complex spectral profile for a particular synthesis technique. We found that the DLP technique has the highest performance and executes in the least amount of time. However, a GA could not efficiently synthesize an LPG, but produced a refractive index change profile that can be implemented using a common LPG fabrication system. It is shown that the experimental results obtained with the GA are superior to that obtained with the DLP technique. Index Terms-Carbon-dioxide (CO 2) laser, complex spectrum, genetic algorithm (GA), layer-peeling technique, long-period gratings (LPGs). I. INTRODUCTION O VER the years, it has become important to design appropriate optical filters, for example, fiber gratings, to achieve a desired spectral response. It is important, when designing grating structures, to strictly monitor the complexity of the index modulation of the grating structure, such that it can be practically realized in the optical fiber core during the grating fabrication process. At present, long-period gratings (LPGs) contribute a great deal to the high-speed optical fiber communication industry with their guided-to-cladding mode power exchange. Due to the low insertion loss, low backreflection, and ease of fabrication of LPGs [1], these grating structures are popular in the gain flattening of erbium-doped fiber amplifiers [2] and add-drop multiplexing [3], [4]. Currently, two classes of the optical filter design process exist, namely, filter analysis and filter synthesis [5]. During the analysis of optical filters, the spectral response, dispersion, and grating strength properties are calculated, given a physical Manuscript

Research paper thumbnail of Optical Add/drop Multiplexing Performed Using Broadband Transmission Filters and a Narrowband Reflection Filter

satnac.org.za

Abstract—We propose and demonstrate the concept of an optical add/drop multiplexing (OADM) device... more Abstract—We propose and demonstrate the concept of an optical add/drop multiplexing (OADM) device utilising a pair of broadband transmission filters and a narrowband reflection filter. Numerical simulations are used to illustrate transmission filter performance using the ...

Research paper thumbnail of Manufacturing of azimuthally symmetric long-period fibre gratings using a CO2 laser

E.1 Comparison of different Optical fibres F Calculation of coupling constants in LPGs 194 F.1 Co... more E.1 Comparison of different Optical fibres F Calculation of coupling constants in LPGs 194 F.1 Coupling constant calculation process F.1.1 Obtaining effective refractive index nrife of the LPoi guided mode F.1.2 Obtaining effective refractive index <II of the specific LPi n, nth cladding mode F.1.3 Simplifying and solving expressions to obtain coupling constants G Flow graph for Simulation programs 205 G.1 Flow graph illustrating the simulation of short-and long-period fibre gratings CONTENTS H Overview of ECODRIVE03 drive controller H.1 Function Overview H.2 Configuration setup for Drive Controller H.3 Communication with ASCII protocol H.3.1 Actuating a Specific Bus User H.3.2 Read accessing a parameter H.3.3 Write accessing a parameter H.3.4 Layout of ECODRIVE03 DKC Drive Controller I Computer Control program 1.1 Introduction 1.1.1 Overview of computer control program J Gaussian Optic Theory J.1 Gaussian Beam Optics J.2 Focussing and Collimating J.3 Optics Formulas J.4 Optics Glossary K SOLIDWORKS drawings of machined plastic blocks K.1 Discussion on the SOLIDWORKS drawings 250 K.

Research paper thumbnail of Design and fabrication of long-period fibre gratings and wavelength-selective couplers for wavelength-division multiplexing networks

Research paper thumbnail of Optical add / drop multiplexer using short-and chirped long-period fibre gratings for dense wavelength-division multiplexing

We propose and demonstrate the use of a novel wavelength-tuneable optical add/drop multiplexer (O... more We propose and demonstrate the use of a novel wavelength-tuneable optical add/drop multiplexer (OADM) device based on fibre Bragg gratings (FBGs) and chirped long-period gratings (CLPGs) having a broad transmission spectrum. Numerical simulations predict bandwidths in the order of 40 nm and higher. Fabrication of the symmetric CLPGs, and the method of strain used for tuning of the fibre Bragg grating are also discussed.

Research paper thumbnail of Motivational factors, customer engagement and loyalty in the South African mobile instant messaging environment: moderating effect of application usage

European Business Review, 2020

Purpose The purpose of this paper is to examine specific gratifications obtained from using mobil... more Purpose The purpose of this paper is to examine specific gratifications obtained from using mobile instant messaging (MIM) applications by applying the uses and gratifications theory. This study explores the relationships between motivational factors, customer engagement and loyalty for existing WhatsApp subscribers in South Africa, as well as the moderating effect of application usage. Design/methodology/approach A descripto-explanatory research design was used in this quantitative study and 282 responses from an online survey were analysed. Structural equation modelling was used to test the study’s hypotheses. Findings The study reveals that utilitarian and hedonic motivation impact customer engagement positively in using WhatsApp, which, in turn, impacts loyalty. Social motivation in using WhatsApp bore no relationship with customer engagement. Furthermore, medium application usage moderates the link between customer engagement and utilitarian and hedonic motivation. Research lim...

Research paper thumbnail of Digital Design of Broadband Long-Period Fibre Gratings by an Inverse Scattering Algorithm with Flip-Flop Optimisation

SAIEE Africa Research Journal, 2012

A discrete inverse scattering method, known as layer-peeling, is used to synthesise a LPFG (long-... more A discrete inverse scattering method, known as layer-peeling, is used to synthesise a LPFG (long-period fibre grating) from a desired complex spectrum by a direct solution of the coupled-mode equations, while simultaneously determining the physical properties of the layered structure. The physical properties of the grating structure are determined in a recursive layer-by-layer manner by using causality arguments to design LPFGs exhibiting a flat-top spectral profile. The results obtained from the layer-peeling method are optimised using the flip-flop method to ease the fabrication process. We found that the layer-peeling method has the highest performance and executes in the least amount of time. A discussion of possible applications where optimised broadband LPFGs could be utilised in the field of telecommunications and sensing demonstrates the importance of the results.

Research paper thumbnail of Supercontinuum generation with a figure-eight fiber laser

Third European Workshop on Optical Fibre Sensors, 2007

ABSTRACT We use a figure-eight fibre laser with a photonic crystal fibre NALM (nonlinear amplifyi... more ABSTRACT We use a figure-eight fibre laser with a photonic crystal fibre NALM (nonlinear amplifying loop mirror) to produce a moderate supercontinuum from 1440 nm - 1680 nm in highly nonlinear dispersion shifted fibre. We also observe a 743 nm band in the fluorescence of the erbium doped amplifier outside the figure-eight fibre laser.

Research paper thumbnail of Design and fabrication of low-loss broadband transmission filters for dense wavelength-division multiplexing networks

AFRICON 2007, 2007

We present a method to design broadband optical transmission filters from complex spectrum profil... more We present a method to design broadband optical transmission filters from complex spectrum profiles, for application in dense wavelength-division multiplexing (DWDM) systems. A discrete inverse scattering method, known as layer-peeling, is used to reconstruct a long-period fibre grating (LPG) structure from a specified realisable complex spectrum by a direct solution of the coupled-mode equations, while simultaneously determining the physical properties

Research paper thumbnail of Wavelength-tuneable add/drop multiplexer using broadband transmission filters and a narrowband reflection filter

SPIE Proceedings, 2008

... Ronnie Kritzinger, André Booysen Centre for Optical Communications and Sensors University of ... more ... Ronnie Kritzinger, André Booysen Centre for Optical Communications and Sensors University of Johannesburg, PO Box 524, Auckland Park ... 19th International Conference on Optical Fibre Sensors, edited by David Sampson, Stephen Collins, Kyunghwan Oh, Ryozo Yamauchi ...

Research paper thumbnail of Investigation of the power coupling of novel wavelength-selective couplers incorporating axially symmetric long-period fibre gratings

South African Journal of Science, 2011

Evanescent-field coupling was studied experimentally in novel optical-fibre-based wavelengthselec... more Evanescent-field coupling was studied experimentally in novel optical-fibre-based wavelengthselective couplers, using axially symmetric long-period fibre grating (LPFG) structures. The coupling characteristics of a wavelength-selective coupler at the resonant wavelength were investigated for different LPFG offset distances. It was shown that the wavelength-selective couplers effectively transferred light power at the LPFG resonant wavelength from one fibre to another. The performance of the couplers was consistent with simulations performed in MATLAB using coupled-mode theory.

Research paper thumbnail of Azimuthally symmetric long-period fibre grating fabrication with a TEM 01∗ -mode CO 2 laser

Measurement Science and Technology, 2009

Research paper thumbnail of Design and Fabrication of Novel Broadband Long-Period Fiber Gratings Using Synthesis Techniques

Journal of Lightwave Technology, 2011

We present results of novel broadband long-period gratings (LPGs) that were fabricated axially sy... more We present results of novel broadband long-period gratings (LPGs) that were fabricated axially symmetric in singlemode fiber with a carbon-dioxide laser. The discrete layer-peeling (DLP) technique and a genetic algorithm (GA) were used to design the LPGs. Numerical simulations were used to indicate the performance and absolute error of reconstructing a complex spectral profile for a particular synthesis technique. We found that the DLP technique has the highest performance and executes in the least amount of time. However, a GA could not efficiently synthesize an LPG, but produced a refractive index change profile that can be implemented using a common LPG fabrication system. It is shown that the experimental results obtained with the GA are superior to that obtained with the DLP technique. Index Terms-Carbon-dioxide (CO 2) laser, complex spectrum, genetic algorithm (GA), layer-peeling technique, long-period gratings (LPGs). I. INTRODUCTION O VER the years, it has become important to design appropriate optical filters, for example, fiber gratings, to achieve a desired spectral response. It is important, when designing grating structures, to strictly monitor the complexity of the index modulation of the grating structure, such that it can be practically realized in the optical fiber core during the grating fabrication process. At present, long-period gratings (LPGs) contribute a great deal to the high-speed optical fiber communication industry with their guided-to-cladding mode power exchange. Due to the low insertion loss, low backreflection, and ease of fabrication of LPGs [1], these grating structures are popular in the gain flattening of erbium-doped fiber amplifiers [2] and add-drop multiplexing [3], [4]. Currently, two classes of the optical filter design process exist, namely, filter analysis and filter synthesis [5]. During the analysis of optical filters, the spectral response, dispersion, and grating strength properties are calculated, given a physical Manuscript

Research paper thumbnail of Optical Add/drop Multiplexing Performed Using Broadband Transmission Filters and a Narrowband Reflection Filter

satnac.org.za

Abstract—We propose and demonstrate the concept of an optical add/drop multiplexing (OADM) device... more Abstract—We propose and demonstrate the concept of an optical add/drop multiplexing (OADM) device utilising a pair of broadband transmission filters and a narrowband reflection filter. Numerical simulations are used to illustrate transmission filter performance using the ...