David Moodie - Academia.edu (original) (raw)

Papers by David Moodie

Coatings, 2019

The authors wish to modify the funding section as follows to this paper [...]

In this work performance improvements are described of a low power consumption non-dispersive inf... more In this work performance improvements are described of a low power consumption non-dispersive infrared (NDIR) methane (CH4) gas sensor using customised optical thin film bandpass filters (BPF). BPF’s shape the spectral characteristic of the combined mid infrared III-V based light emitting diode (LED)/ photodiode (PD) light source/detector optopair, enhancing NDIR CH4 sensor performance. The BPF, deposited using a novel microwave plasma assisted pulsed DC sputter deposition process, is deposited at room temperature directly onto the temperature sensitive PD heterostructure. BPF’s comprise germanium (Ge) and niobium pentoxide (Nb2O5) alternating high and low refractive index layers respectively. Two different optical filter designs are progressed; with BPF bandwidths (BWs) of 160 nm and 300 nm. Comparison of modelled and measured NDIR sensor performance is described, highlighting maximized signal to noise ratio (SNR) and minimized cross talk performance benefits. BPF spect...

SPIE Proceedings, 2005

Practical bit error rate measurements on fibre optic communications links in student teaching lab... more Practical bit error rate measurements on fibre optic communications links in student teaching laboratories," Proc. SPIE 9664, Ninth International Topical Meeting on Education and Training in Optics and Photonics, 96642I (

Optical Sensing and Detection, 2010

ABSTRACT

Education and Training in Optics and Photonics, 2003

The burgeoning growth of the worldwide photonics and optical communications industry has imposed ... more The burgeoning growth of the worldwide photonics and optical communications industry has imposed ever increasing demands on the supply of suitably skilled engineers and scientists who can design, install and operate modern photonics systems. In recognition of this need OptoSci, in collaboration with university academics, has commercially developed a series of hardware based teaching packages in optics, optoelectronics and optical communications. Each educator kit is fully self-contained, including all of the optoelectronic hardware and comprehensive literature support. This saves the academic tutor considerable development time and enables the kits to be immediately installed in the photonics teaching laboratory to support accompanying lecture courses. A fundamental design objective of our educator kits is to provide students with hands-on practical experience of photonics components, instruments and systems and allow them to investigate essential physical principles and key technical issues relevant to their lecture courses. This paper will outline the design philosophy behind the products to meet the desired educational aims, and then examine the specific educational objectives and topics investigated in each educator kit.

Education and Training in Optics and Photonics, 2007

In this paper we describe a new family of teaching packages designed to offer a practical introdu... more In this paper we describe a new family of teaching packages designed to offer a practical introduction for graduate students of Science and Engineering to the topic of wavelength division multiplexing (WDM) in fibre optics. The teaching packages described here provide students with the background theory before embarking on a series of practical experiments to demonstrate the operation and characterisation of WDM components and systems. The packages are designed in a modular format to allow the user to develop from the fundamentals of fibre optical components through to the concepts of WDM and dense WDM (DWDM) systems and onto advanced topics covering aspects of Bragg gratings. This paper examines the educational objectives, background theory, and typical results for these educational packages.

Fifth International Topical Meeting on Education and Training in Optics, 1997

SPIE Proceedings, 1993

ABSTRACT

SPIE Proceedings, 2005

ABSTRACT

17th International Conference on Optical Fibre Sensors, 2005

A novel variation in optical correlation spectroscopy is presented. A semiconductor optical ampli... more A novel variation in optical correlation spectroscopy is presented. A semiconductor optical amplifier (SOA) is employed as the light source and an optical fibre delay line is used to achieve the 180° phase shift between the reference and measurement signals. The system was tested using acetylene (C2H2) gas. Absorption data from the HITRAN database is used to model the theoretical response of the system. Experimental results for the detection of various acetylene gas concentrations have been obtained and compared with theory.

Opto-Ireland 2005: Photonic Engineering, 2005

ABSTRACT Optical fibre communications has proved to be one of the key application areas, which cr... more ABSTRACT Optical fibre communications has proved to be one of the key application areas, which created, and ultimately propelled the global growth of the photonics industry over the last twenty years. Consequently the teaching of the principles of optical fibre communications has become integral to many university courses covering photonics technology. However to reinforce the fundamental principles and key technical issues students examine in their lecture courses and to develop their experimental skills, it is critical that the students also obtain hands-on practical experience of photonics components, instruments and systems in an associated teaching laboratory. In recognition of this need OptoSci, in collaboration with university academics, commercially developed a fibre optic communications based educational package (ED-COM). This educator kit enables students to; investigate the characteristics of the individual communications system components (sources, transmitters, fibre, receiver), examine and interpret the overall system performance limitations imposed by attenuation and dispersion, conduct system design and performance analysis. To further enhance the experimental programme examined in the fibre optic communications kit, an extension module to ED-COM has recently been introduced examining one of the most significant performance parameters of digital communications systems, the bit error rate (BER). This add-on module, BER(COM), enables students to generate, evaluate and investigate signal quality trends by examining eye patterns, and explore the bit-rate limitations imposed on communication systems by noise, attenuation and dispersion. This paper will examine the educational objectives, background theory, and typical results for these educator kits, with particular emphasis on BER(COM).

SPIE Proceedings, 2000

The Erbium Doped Fiber Amplifier (EDFA) has now replaced optoelectronic repeaters as the primary ... more The Erbium Doped Fiber Amplifier (EDFA) has now replaced optoelectronic repeaters as the primary design option for extendmg the range and capacity of the World's fiber optic telecommunications systems. In a broader sense, optical amplifiers are the basis of all lasers. It is therefore essential that students of science and engineering have a broad appreciation of, and practical familiarity with, optical amplifiers in general, EDFAs in particular and their applications in lasers. To achieve these objectives, Strathclyde University in collaboration with OPT0ScI LTD. have developed an EDFA I Laser educator kit which enables students to experimentally investigate the gain and noise characteristics of an EDFA, including issues such as signal and pump saturation, gain efficiency, amplified spontaneous emission and optical beat noise. With a simple extension to the basic amplifier kit the students are able to construct an erbium doped fiber ring laser and to investigate its power characteristics (threshold and slope efficiency) as a function of output coupling ratio and intra-cavity loss. The experimental objectives, design philosophies, hardware, experimental procedures and results will be examined in detail in this paper.

SPIE Proceedings, 2002

In response to industry's need for scientists and engineers skilled in the design, manufacture an... more In response to industry's need for scientists and engineers skilled in the design, manufacture and operation of photonics systems, Strathclyde University and OptoSci Ltd. have developed a suite of Photonics Educator Kits, which enable students to experimentally investigate all of the major technical features, principles and design issues of optical waveguides, optical communications systems, erbium doped fiber amplifiers and lasers. To support these applications experiments we have recently added a range ofkits enabling students to experimentally investigate the basics of physical optics covering reflection, refraction, polarisation, diffraction, coherence and interference. In this paper, we will describe the educational objectives and the design philosophies behind the development of these kits. To illustrate these, full details of the experimental procedures, the results and the benefits to the student will be discussed for the recently upgraded optical communications kit and the erbium doped fiber amplifier (EDFA) system, in particular addressing the crucially important noise characteristics of optical amplifiers. 1. INI'RODUCTION Modern Optics and Photonics currently drive major technical advancement in such a diversity of technologies as telecommunications, measurement science, industrial and environmental sensing, medical diagnostics and bio-sciences. In particular, the world's main trunk telecommunications systems, the global internet and mobile phone communications systems are all founded on Photonics networks. Companies operating in these fields have an ever increasing demand for highly skilled scientists and engineers who can design, build, analyse, install and operate photonic systems. There is no doubt that the learning experience ofthese professional technologists is greatly enhanced during their graduate or undergraduate studies by exposure to hands on, practical experience of photonics components and systems. Strathclyde University, in collaboration with OptoSci Ltd., have developed a suite of Photonics Educator Kits which enable students to experimentally investigate all of the major technical features, principles and design issues of optical waveguides, optical communications systems, erbium doped fiber amplifiers and lasers. These applications kits are now supported by a range of experiments examining the fundamentals of physical optics, covering reflection, refraction, polarisation, diffraction, coherence and interference. In the development of all of these systems we adhere to a strict design philosophy and procedure, which ensures that all ofthe important educational objectives are met. A working knowledge and understanding of the components of a fiber optic communications system and the limits imposed on the system performance by the component characteristics are invaluable for any student going on to work with photonic systems. Hence, two of the most important kits address optical communications systems and their component parts including optical amplifiers. Details of a previous version of the optical communications system kit and some aspects ofthe EDFA kit have been reported in the past1'2 Recently, we have upgraded the communications kit to use 62.5/125pm graded index fiber (replacing the multi mode step index fiber). This enables the students to more clearly explore the separate effects of material and modal dispersion and their effects on the system performance. The most important characteristic of optical amplifiers as regards the limitations they impose on system performance is noise. Recent adaptations to the EDFA kit enable students to investigate the noise characteristics of the amplifier and simple exercises based on their noise measurements allow them to appreciate the effects of amplifier noise on the overall system performance. Here we describe these two kits in detail covering educational objectives, design philosophies, the hardware involved, the experimental procedures followed by students and sample results. For the EDFA kit we will concentrate on the noise characteristics as the gain characteristics have been addressed in previous publications1' 2

Sensors and Actuators B: Chemical, 1998

... Specific examples of these may include oil exploration platforms and pipeline monitoring syst... more ... Specific examples of these may include oil exploration platforms and pipeline monitoring systems looking for localised leakage. In these specific applications, optics has two distinct advantages: • Interrogation through optical fibre links can ... These remote interrogation systems ...

Proceedings of the IEEE, 2000

Optics Letters, 1992

The evanescent field coupling resonances between a single-mode optical fiber and a multimode plan... more The evanescent field coupling resonances between a single-mode optical fiber and a multimode planar waveguide overlay are sensitive in position to the refractive index of the superstrate material in contact with the top surface of the overlay. By using lithium niobate and zinc selenide in the role of the overlay and Cargille refractive-index oil as the superstrate, this principle has been investigated for use in refractometry. The ability to resolve index changes of <1 x 10-5 has been clearly demonstrated for an open-loop mode of operation by using intensity modulation, and a method of closed-loop operation is proposed by using active materials such as lithium niobate in the role of the overlay to provide independent feedback control of the resonance position.

Measurement Science and Technology, 2006

An alternative method of gas detection using optical correlation spectroscopy (OCS) has been inve... more An alternative method of gas detection using optical correlation spectroscopy (OCS) has been investigated. A semiconductor optical amplifier (SOA) is employed to transmit broadband light through a reference and measurement cell containing the absorbing species, and the required 180° phase shift between the reference and measurement signal is achieved using an optical fibre delay line. The use of a single

Journal of Physics: Conference Series, 2009

A new optoelectronic sensor for the real time monitoring of key components such as valves and con... more A new optoelectronic sensor for the real time monitoring of key components such as valves and connectors within the subsea production equipment for leaks of hydraulic fluid is reported. The sensor is capable of detecting low concentrations of such fluids, allowing the early detection of small leaks, and the ability to monitor the evolution of the leak-rate with time, hence providing an important new tool in complying with environmental requirements, enabling early intervention and optimising subsea production

IEE Proceedings - Science, Measurement and Technology, 1995

ABSTRACT

Crystals, 2020

Self-cleaning windows are well known for their ability to function with airborne pollutants, but ... more Self-cleaning windows are well known for their ability to function with airborne pollutants, but there is a growing industry for semi-permanent subaquatic optical devices, where the performance of such windows should be considered. Here sol-gel technology is explored as a means of producing self-cleaning, subaquatic, sapphire windows. We demonstrate removal of marine bacteria and, in the worst-case contamination scenario, dead North Sea crude oil (API 35). This greasy contaminant was smeared across the windows to effectively reduce optical transmission strength to just 54%. The titania-based sol-gel-coated windows can restore transmission to within 10% of the clean value in less than one day, unlike standard sapphire windows, which lose 68% transmission following contamination and aquatic submergence over the same duration. A range of theories to enhance the self-cleaning performance of the sol-gel coating were explored, but none of the tested variables were able to provide any enha...

Coatings, 2019

The authors wish to modify the funding section as follows to this paper [...]

In this work performance improvements are described of a low power consumption non-dispersive inf... more In this work performance improvements are described of a low power consumption non-dispersive infrared (NDIR) methane (CH4) gas sensor using customised optical thin film bandpass filters (BPF). BPF’s shape the spectral characteristic of the combined mid infrared III-V based light emitting diode (LED)/ photodiode (PD) light source/detector optopair, enhancing NDIR CH4 sensor performance. The BPF, deposited using a novel microwave plasma assisted pulsed DC sputter deposition process, is deposited at room temperature directly onto the temperature sensitive PD heterostructure. BPF’s comprise germanium (Ge) and niobium pentoxide (Nb2O5) alternating high and low refractive index layers respectively. Two different optical filter designs are progressed; with BPF bandwidths (BWs) of 160 nm and 300 nm. Comparison of modelled and measured NDIR sensor performance is described, highlighting maximized signal to noise ratio (SNR) and minimized cross talk performance benefits. BPF spect...

SPIE Proceedings, 2005

Practical bit error rate measurements on fibre optic communications links in student teaching lab... more Practical bit error rate measurements on fibre optic communications links in student teaching laboratories," Proc. SPIE 9664, Ninth International Topical Meeting on Education and Training in Optics and Photonics, 96642I (

Optical Sensing and Detection, 2010

ABSTRACT

Education and Training in Optics and Photonics, 2003

The burgeoning growth of the worldwide photonics and optical communications industry has imposed ... more The burgeoning growth of the worldwide photonics and optical communications industry has imposed ever increasing demands on the supply of suitably skilled engineers and scientists who can design, install and operate modern photonics systems. In recognition of this need OptoSci, in collaboration with university academics, has commercially developed a series of hardware based teaching packages in optics, optoelectronics and optical communications. Each educator kit is fully self-contained, including all of the optoelectronic hardware and comprehensive literature support. This saves the academic tutor considerable development time and enables the kits to be immediately installed in the photonics teaching laboratory to support accompanying lecture courses. A fundamental design objective of our educator kits is to provide students with hands-on practical experience of photonics components, instruments and systems and allow them to investigate essential physical principles and key technical issues relevant to their lecture courses. This paper will outline the design philosophy behind the products to meet the desired educational aims, and then examine the specific educational objectives and topics investigated in each educator kit.

Education and Training in Optics and Photonics, 2007

In this paper we describe a new family of teaching packages designed to offer a practical introdu... more In this paper we describe a new family of teaching packages designed to offer a practical introduction for graduate students of Science and Engineering to the topic of wavelength division multiplexing (WDM) in fibre optics. The teaching packages described here provide students with the background theory before embarking on a series of practical experiments to demonstrate the operation and characterisation of WDM components and systems. The packages are designed in a modular format to allow the user to develop from the fundamentals of fibre optical components through to the concepts of WDM and dense WDM (DWDM) systems and onto advanced topics covering aspects of Bragg gratings. This paper examines the educational objectives, background theory, and typical results for these educational packages.

Fifth International Topical Meeting on Education and Training in Optics, 1997

SPIE Proceedings, 1993

ABSTRACT

SPIE Proceedings, 2005

ABSTRACT

17th International Conference on Optical Fibre Sensors, 2005

A novel variation in optical correlation spectroscopy is presented. A semiconductor optical ampli... more A novel variation in optical correlation spectroscopy is presented. A semiconductor optical amplifier (SOA) is employed as the light source and an optical fibre delay line is used to achieve the 180° phase shift between the reference and measurement signals. The system was tested using acetylene (C2H2) gas. Absorption data from the HITRAN database is used to model the theoretical response of the system. Experimental results for the detection of various acetylene gas concentrations have been obtained and compared with theory.

Opto-Ireland 2005: Photonic Engineering, 2005

ABSTRACT Optical fibre communications has proved to be one of the key application areas, which cr... more ABSTRACT Optical fibre communications has proved to be one of the key application areas, which created, and ultimately propelled the global growth of the photonics industry over the last twenty years. Consequently the teaching of the principles of optical fibre communications has become integral to many university courses covering photonics technology. However to reinforce the fundamental principles and key technical issues students examine in their lecture courses and to develop their experimental skills, it is critical that the students also obtain hands-on practical experience of photonics components, instruments and systems in an associated teaching laboratory. In recognition of this need OptoSci, in collaboration with university academics, commercially developed a fibre optic communications based educational package (ED-COM). This educator kit enables students to; investigate the characteristics of the individual communications system components (sources, transmitters, fibre, receiver), examine and interpret the overall system performance limitations imposed by attenuation and dispersion, conduct system design and performance analysis. To further enhance the experimental programme examined in the fibre optic communications kit, an extension module to ED-COM has recently been introduced examining one of the most significant performance parameters of digital communications systems, the bit error rate (BER). This add-on module, BER(COM), enables students to generate, evaluate and investigate signal quality trends by examining eye patterns, and explore the bit-rate limitations imposed on communication systems by noise, attenuation and dispersion. This paper will examine the educational objectives, background theory, and typical results for these educator kits, with particular emphasis on BER(COM).

SPIE Proceedings, 2000

The Erbium Doped Fiber Amplifier (EDFA) has now replaced optoelectronic repeaters as the primary ... more The Erbium Doped Fiber Amplifier (EDFA) has now replaced optoelectronic repeaters as the primary design option for extendmg the range and capacity of the World's fiber optic telecommunications systems. In a broader sense, optical amplifiers are the basis of all lasers. It is therefore essential that students of science and engineering have a broad appreciation of, and practical familiarity with, optical amplifiers in general, EDFAs in particular and their applications in lasers. To achieve these objectives, Strathclyde University in collaboration with OPT0ScI LTD. have developed an EDFA I Laser educator kit which enables students to experimentally investigate the gain and noise characteristics of an EDFA, including issues such as signal and pump saturation, gain efficiency, amplified spontaneous emission and optical beat noise. With a simple extension to the basic amplifier kit the students are able to construct an erbium doped fiber ring laser and to investigate its power characteristics (threshold and slope efficiency) as a function of output coupling ratio and intra-cavity loss. The experimental objectives, design philosophies, hardware, experimental procedures and results will be examined in detail in this paper.

SPIE Proceedings, 2002

In response to industry's need for scientists and engineers skilled in the design, manufacture an... more In response to industry's need for scientists and engineers skilled in the design, manufacture and operation of photonics systems, Strathclyde University and OptoSci Ltd. have developed a suite of Photonics Educator Kits, which enable students to experimentally investigate all of the major technical features, principles and design issues of optical waveguides, optical communications systems, erbium doped fiber amplifiers and lasers. To support these applications experiments we have recently added a range ofkits enabling students to experimentally investigate the basics of physical optics covering reflection, refraction, polarisation, diffraction, coherence and interference. In this paper, we will describe the educational objectives and the design philosophies behind the development of these kits. To illustrate these, full details of the experimental procedures, the results and the benefits to the student will be discussed for the recently upgraded optical communications kit and the erbium doped fiber amplifier (EDFA) system, in particular addressing the crucially important noise characteristics of optical amplifiers. 1. INI'RODUCTION Modern Optics and Photonics currently drive major technical advancement in such a diversity of technologies as telecommunications, measurement science, industrial and environmental sensing, medical diagnostics and bio-sciences. In particular, the world's main trunk telecommunications systems, the global internet and mobile phone communications systems are all founded on Photonics networks. Companies operating in these fields have an ever increasing demand for highly skilled scientists and engineers who can design, build, analyse, install and operate photonic systems. There is no doubt that the learning experience ofthese professional technologists is greatly enhanced during their graduate or undergraduate studies by exposure to hands on, practical experience of photonics components and systems. Strathclyde University, in collaboration with OptoSci Ltd., have developed a suite of Photonics Educator Kits which enable students to experimentally investigate all of the major technical features, principles and design issues of optical waveguides, optical communications systems, erbium doped fiber amplifiers and lasers. These applications kits are now supported by a range of experiments examining the fundamentals of physical optics, covering reflection, refraction, polarisation, diffraction, coherence and interference. In the development of all of these systems we adhere to a strict design philosophy and procedure, which ensures that all ofthe important educational objectives are met. A working knowledge and understanding of the components of a fiber optic communications system and the limits imposed on the system performance by the component characteristics are invaluable for any student going on to work with photonic systems. Hence, two of the most important kits address optical communications systems and their component parts including optical amplifiers. Details of a previous version of the optical communications system kit and some aspects ofthe EDFA kit have been reported in the past1'2 Recently, we have upgraded the communications kit to use 62.5/125pm graded index fiber (replacing the multi mode step index fiber). This enables the students to more clearly explore the separate effects of material and modal dispersion and their effects on the system performance. The most important characteristic of optical amplifiers as regards the limitations they impose on system performance is noise. Recent adaptations to the EDFA kit enable students to investigate the noise characteristics of the amplifier and simple exercises based on their noise measurements allow them to appreciate the effects of amplifier noise on the overall system performance. Here we describe these two kits in detail covering educational objectives, design philosophies, the hardware involved, the experimental procedures followed by students and sample results. For the EDFA kit we will concentrate on the noise characteristics as the gain characteristics have been addressed in previous publications1' 2

Sensors and Actuators B: Chemical, 1998

... Specific examples of these may include oil exploration platforms and pipeline monitoring syst... more ... Specific examples of these may include oil exploration platforms and pipeline monitoring systems looking for localised leakage. In these specific applications, optics has two distinct advantages: • Interrogation through optical fibre links can ... These remote interrogation systems ...

Proceedings of the IEEE, 2000

Optics Letters, 1992

The evanescent field coupling resonances between a single-mode optical fiber and a multimode plan... more The evanescent field coupling resonances between a single-mode optical fiber and a multimode planar waveguide overlay are sensitive in position to the refractive index of the superstrate material in contact with the top surface of the overlay. By using lithium niobate and zinc selenide in the role of the overlay and Cargille refractive-index oil as the superstrate, this principle has been investigated for use in refractometry. The ability to resolve index changes of <1 x 10-5 has been clearly demonstrated for an open-loop mode of operation by using intensity modulation, and a method of closed-loop operation is proposed by using active materials such as lithium niobate in the role of the overlay to provide independent feedback control of the resonance position.

Measurement Science and Technology, 2006

An alternative method of gas detection using optical correlation spectroscopy (OCS) has been inve... more An alternative method of gas detection using optical correlation spectroscopy (OCS) has been investigated. A semiconductor optical amplifier (SOA) is employed to transmit broadband light through a reference and measurement cell containing the absorbing species, and the required 180° phase shift between the reference and measurement signal is achieved using an optical fibre delay line. The use of a single

Journal of Physics: Conference Series, 2009

A new optoelectronic sensor for the real time monitoring of key components such as valves and con... more A new optoelectronic sensor for the real time monitoring of key components such as valves and connectors within the subsea production equipment for leaks of hydraulic fluid is reported. The sensor is capable of detecting low concentrations of such fluids, allowing the early detection of small leaks, and the ability to monitor the evolution of the leak-rate with time, hence providing an important new tool in complying with environmental requirements, enabling early intervention and optimising subsea production

IEE Proceedings - Science, Measurement and Technology, 1995

ABSTRACT

Crystals, 2020

Self-cleaning windows are well known for their ability to function with airborne pollutants, but ... more Self-cleaning windows are well known for their ability to function with airborne pollutants, but there is a growing industry for semi-permanent subaquatic optical devices, where the performance of such windows should be considered. Here sol-gel technology is explored as a means of producing self-cleaning, subaquatic, sapphire windows. We demonstrate removal of marine bacteria and, in the worst-case contamination scenario, dead North Sea crude oil (API 35). This greasy contaminant was smeared across the windows to effectively reduce optical transmission strength to just 54%. The titania-based sol-gel-coated windows can restore transmission to within 10% of the clean value in less than one day, unlike standard sapphire windows, which lose 68% transmission following contamination and aquatic submergence over the same duration. A range of theories to enhance the self-cleaning performance of the sol-gel coating were explored, but none of the tested variables were able to provide any enha...