title: Development and Characterisation of Plasmonic Devices for Sensing Applications

authors: Sedoglavich, Nemanya

subjects: Plasmonic

abstract: In recent years, discoveries and advances that utilise nano-scale (10^-9m) structures and associated phenomena have led to a number of entirely new areas of research in the fields of physics, chemistry, biology, and materials science. The photonic field of plasmonics is the study of light interaction with nanometer-scaled metal-dielectric features, which gives rise to a variety of phenomena, including surface plasmon resonance, localised surface plasmon resonance, and metal enhanced fluorescence. The focus of this thesis is on the development and characterisation of nanophotonic devices, which utilise plasmonic phenomena and have potential for sensor applications.
During the course of this research a surface plasmon resonance analysis platform was devised, which utilises the gold grating of commercially available compact disks as the sensing substrate. This measurement method offers a high resolution refractive index analysis of gases and surface chemistry and is capable of analysing a large number of samples by scanning over the entire disk surface. The system implements a method of phase-polarisation contrast to improve the sensing performance. It enhances signal detection through redistributing the residual p-polarised waves, which have been strongly absorbed by the surface plasmon resonance substrate/sensor. This effectively lowers the reflected light intensity at the surface plasmon resonance minimum. The scheme results in the deepening of the intensity minimum to below 3.5% reflection and the enhancement of resonance to non-resonance contrast by up to 14 times, and thereby increasing sensitivity.
A range of new nanophotonic structures have been modelled, developed, fabricated, and characterised, which we call wavelength and polarisation selective polariton generators (SPGs). These polarisation-sensitive structures combine a tuneable plasmon resonator and a subwavelength aperture to selectively generate and transmit polaritons of a desired wavelength through a central nanohole. Individual SPGs permit modulation of transmission intensity, with calculated enhanced optical transmission (ratio of output to input flux) of up to 10 and up to 4-fold measured amplitude modulation. The paired SPGs gave rise to multiple spectrally discrete transmission peaks which, when modulated, provide a multi-state operation in a single device. The measured amplitude modulation was up to 10-fold. For the linearly continuous SPG, by controlling the polarisation as a tuning variable, it selectively generated and transported polaritons of a desired wavelength. It exhibited a spectral shift of 40 nm over the full range of polarisation angles. The modelled enhanced optical transmission was calculated to be up to 17.2. An instrument was developed for measuring and characterising light transmission through single nanoholes, nanohole arrays, and other complex structures. The operational characteristics of these elements show close agreement between model predictions and experimental data. It also demonstrates new designs of plasmonic structures which utilise selective behaviour based on the polarisation of incident light.

text: Development and Characterisation of Plasmonic Devices for Sensing Applications In recent years, discoveries and advances that utilise nano-scale (10^-9m) structures and associated phenomena have led to a number of entirely new areas of research in the fields of physics, chemistry, biology, and materials science. The photonic field of plasmonics is the study of light interaction with nanometer-scaled metal-dielectric features, which gives rise to a variety of phenomena, including surface plasmon resonance, localised surface plasmon resonance, and metal enhanced fluorescence. The focus of this thesis is on the development and characterisation of nanophotonic devices, which utilise plasmonic phenomena and have potential for sensor applications.
During the course of this research a surface plasmon resonance analysis platform was devised, which utilises the gold grating of commercially available compact disks as the sensing substrate. This measurement method offers a high resolution refractive index analysis of gases and surface chemistry and is capable of analysing a large number of samples by scanning over the entire disk surface. The system implements a method of phase-polarisation contrast to improve the sensing performance. It enhances signal detection through redistributing the residual p-polarised waves, which have been strongly absorbed by the surface plasmon resonance substrate/sensor. This effectively lowers the reflected light intensity at the surface plasmon resonance minimum. The scheme results in the deepening of the intensity minimum to below 3.5% reflection and the enhancement of resonance to non-resonance contrast by up to 14 times, and thereby increasing sensitivity.
A range of new nanophotonic structures have been modelled, developed, fabricated, and characterised, which we call wavelength and polarisation selective polariton generators (SPGs). These polarisation-sensitive structures combine a tuneable plasmon resonator and a subwavelength aperture to selectively generate and transmit polaritons of a desired wavelength through a central nanohole. Individual SPGs permit modulation of transmission intensity, with calculated enhanced optical transmission (ratio of output to input flux) of up to 10 and up to 4-fold measured amplitude modulation. The paired SPGs gave rise to multiple spectrally discrete transmission peaks which, when modulated, provide a multi-state operation in a single device. The measured amplitude modulation was up to 10-fold. For the linearly continuous SPG, by controlling the polarisation as a tuning variable, it selectively generated and transported polaritons of a desired wavelength. It exhibited a spectral shift of 40 nm over the full range of polarisation angles. The modelled enhanced optical transmission was calculated to be up to 17.2. An instrument was developed for measuring and characterising light transmission through single nanoholes, nanohole arrays, and other complex structures. The operational characteristics of these elements show close agreement between model predictions and experimental data. It also demonstrates new designs of plasmonic structures which utilise selective behaviour based on the polarisation of incident light.

year: 2009

title: Unpredictable, Incurable, Unemployable? A Collection of Constructed Narratives Exploring the Experiences of People with Chronic Conditions in Relation to Finding and Keeping Work

authors: Uerata, Lynley Moana

subjects: Chronic Conditions

abstract: People with chronic conditions have a health problem that is characterised by longevity, permanence, incurability and unpredictability of symptoms. They face significant challenges in gaining and maintaining employment, and are often seen as unemployable. As Chapter One shows, previous research on this topic tends to focus on selected aspects of their experiences. There is little literature which examines the employment issues of people with chronic conditions in a way that pays attention to the everyday life context. The main research questions addressed in this thesis are: What are the subjective experiences of people with chronic conditions in the context of finding and keeping paid employment? What are the meanings they ascribe to those experiences? How do they interact with and operate within the micro- structures of the family, friends, the medical system and government agencies? What is the role of societal norms, values and dominant ideologies? Chapter Two describes how this research draws on a “critical interpretivist” perspective and qualitative methodology to (re)present four people‟s own stories in their own words in order to explore the subjective experiences of people with chronic conditions within the context of work and broader social structures. Two in-depth, semi-structured interviews were undertaken with these four participants, designed to capture their subjective experiences and enable the researcher to retell their stories. Their stories form the heart of the thesis in Chapter Three. In Chapter Four, each narrative is summarised to highlight the employment issues faced by each participant, and answers are provided to the research questions. People with chronic conditions contend with a complex reality. These complexities stem from the fact that they are permanent, incurable and their symptoms unpredictable. And, because there lacks policies or political mechanisms that acknowledge the complex realities they face, they contend with these by themselves and with the people who are willing to assist them. In some circumstances, they are eminently employable.

text: Unpredictable, Incurable, Unemployable? A Collection of Constructed Narratives Exploring the Experiences of People with Chronic Conditions in Relation to Finding and Keeping Work People with chronic conditions have a health problem that is characterised by longevity, permanence, incurability and unpredictability of symptoms. They face significant challenges in gaining and maintaining employment, and are often seen as unemployable. As Chapter One shows, previous research on this topic tends to focus on selected aspects of their experiences. There is little literature which examines the employment issues of people with chronic conditions in a way that pays attention to the everyday life context. The main research questions addressed in this thesis are: What are the subjective experiences of people with chronic conditions in the context of finding and keeping paid employment? What are the meanings they ascribe to those experiences? How do they interact with and operate within the micro- structures of the family, friends, the medical system and government agencies? What is the role of societal norms, values and dominant ideologies? Chapter Two describes how this research draws on a “critical interpretivist” perspective and qualitative methodology to (re)present four people‟s own stories in their own words in order to explore the subjective experiences of people with chronic conditions within the context of work and broader social structures. Two in-depth, semi-structured interviews were undertaken with these four participants, designed to capture their subjective experiences and enable the researcher to retell their stories. Their stories form the heart of the thesis in Chapter Three. In Chapter Four, each narrative is summarised to highlight the employment issues faced by each participant, and answers are provided to the research questions. People with chronic conditions contend with a complex reality. These complexities stem from the fact that they are permanent, incurable and their symptoms unpredictable. And, because there lacks policies or political mechanisms that acknowledge the complex realities they face, they contend with these by themselves and with the people who are willing to assist them. In some circumstances, they are eminently employable.

year: 2011

title: HIV diagnoses in indigenous peoples: comparison of Australia, Canada and New Zealand

authors: Shea, Beverley

subjects: HIV

abstract: In industrial countries, a number of factors put indigenous peoples at increased risk of HIV infection. National surveillance data between 1999 and 2008 provided diagnoses for Aboriginal and Torres Strait Islanders (Australia), First Nations, Inuit and Métis (Canada excluding Ontario and Quebec) and Māori (New Zealand). Each country provided similar data for a non-indigenous comparison population. Direct standardisation used the 2001 Canadian Aboriginal male population for comparison of five-year diagnosis rates in 1999–2003 and 2004–2008. Using the general population as denominators, we report diagnosis ratios for presumed heterosexual transmission, men who have sex with men (MSM) and intravenous drug users (IDU). Age standardised HIV diagnosis rates in indigenous peoples in Canada in 2004–2008 (178.1 and 178.4/100 000 for men and women respectively) were higher than in Australia (48.5 and 12.9/100 000) and New Zealand (41.9 and 4.3/100 000). Higher HIV diagnosis rates related to heterosexual contact among Aboriginal peoples, especially women, in Canada confirm a widening epidemic beyond the conventional risk groups. This potential of a generalised epidemic requires urgent attention in Aboriginal communities; available evidence can inform policy and action by all stakeholders. Although less striking in Australia and New Zealand, these findings may be relevant to indigenous peoples in other countries.

text: HIV diagnoses in indigenous peoples: comparison of Australia, Canada and New Zealand In industrial countries, a number of factors put indigenous peoples at increased risk of HIV infection. National surveillance data between 1999 and 2008 provided diagnoses for Aboriginal and Torres Strait Islanders (Australia), First Nations, Inuit and Métis (Canada excluding Ontario and Quebec) and Māori (New Zealand). Each country provided similar data for a non-indigenous comparison population. Direct standardisation used the 2001 Canadian Aboriginal male population for comparison of five-year diagnosis rates in 1999–2003 and 2004–2008. Using the general population as denominators, we report diagnosis ratios for presumed heterosexual transmission, men who have sex with men (MSM) and intravenous drug users (IDU). Age standardised HIV diagnosis rates in indigenous peoples in Canada in 2004–2008 (178.1 and 178.4/100 000 for men and women respectively) were higher than in Australia (48.5 and 12.9/100 000) and New Zealand (41.9 and 4.3/100 000). Higher HIV diagnosis rates related to heterosexual contact among Aboriginal peoples, especially women, in Canada confirm a widening epidemic beyond the conventional risk groups. This potential of a generalised epidemic requires urgent attention in Aboriginal communities; available evidence can inform policy and action by all stakeholders. Although less striking in Australia and New Zealand, these findings may be relevant to indigenous peoples in other countries.

year: 2011