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: Good lattice rules with a composite number of points based on the product weighted star discrepancy

authors: Joe, Stephen

subjects: mathematics

abstract: Rank-1 lattice rules based on a weighted star discrepancy with weights of a product form have been previously constructed under the assumption that the number of points is prime. Here, we extend these results to the non-prime case. We show that if the weights are summable, there exist lattice rules whose weighted star discrepancy is O(n−1+δ), for any δ > 0, with the implied constant independent of the dimension and the number of lattice points, but dependent on δ and the weights. Then we show that the generating vector of such a rule can be constructed using a component-by-component (CBC) technique. The cost of the CBC construction is analysed in the final part of the paper.

text: Good lattice rules with a composite number of points based on the product weighted star discrepancy Rank-1 lattice rules based on a weighted star discrepancy with weights of a product form have been previously constructed under the assumption that the number of points is prime. Here, we extend these results to the non-prime case. We show that if the weights are summable, there exist lattice rules whose weighted star discrepancy is O(n−1+δ), for any δ > 0, with the implied constant independent of the dimension and the number of lattice points, but dependent on δ and the weights. Then we show that the generating vector of such a rule can be constructed using a component-by-component (CBC) technique. The cost of the CBC construction is analysed in the final part of the paper.

year: 2008

title: “Whānau Vibes”: Reclamation of self, space and community within group fitness gyms.

authors: Metekingi, Cydney

abstract: Group fitness gyms are becoming more popular in Aotearoa, New Zealand. This thesis is an investigation of the lived experiences of Māori members within a commercialised fitness space called BFT Hamilton East, located in Kirikiriroa, Hamilton. Drawing on Indigenous anthropology and autoethnography, and grounded in Kaupapa Māori theory, this thesis firstly explores how the gym becomes a site in which Māori members seek to reclaim the narrative around their own bodies. I explore the colonial depictions, the politics of the Indigenous body and how Māori-owned clothing brands contribute to this reclamation. I then examine how Māori gym members use the gym space with a sense of purpose, balancing the values of culture and commercialisation. And finally, I investigate the importance of relational well-being and the use of whanaungatanga and manaakitanga to create a sense of belonging among participants in their search for connection. In foregrounding Indigenous ways of knowing, being and moving in a commercial group fitness gym, this thesis aims to contribute to the anthropological conversations that advocate for the inclusion of Indigenous methodologies into Anthropology, centring Indigenous agency and advocating for the decolonisation of fitness spaces.

text: “Whānau Vibes”: Reclamation of self, space and community within group fitness gyms. Group fitness gyms are becoming more popular in Aotearoa, New Zealand. This thesis is an investigation of the lived experiences of Māori members within a commercialised fitness space called BFT Hamilton East, located in Kirikiriroa, Hamilton. Drawing on Indigenous anthropology and autoethnography, and grounded in Kaupapa Māori theory, this thesis firstly explores how the gym becomes a site in which Māori members seek to reclaim the narrative around their own bodies. I explore the colonial depictions, the politics of the Indigenous body and how Māori-owned clothing brands contribute to this reclamation. I then examine how Māori gym members use the gym space with a sense of purpose, balancing the values of culture and commercialisation. And finally, I investigate the importance of relational well-being and the use of whanaungatanga and manaakitanga to create a sense of belonging among participants in their search for connection. In foregrounding Indigenous ways of knowing, being and moving in a commercial group fitness gym, this thesis aims to contribute to the anthropological conversations that advocate for the inclusion of Indigenous methodologies into Anthropology, centring Indigenous agency and advocating for the decolonisation of fitness spaces.

year: 2025