Sentinel Lymph Node Biopsy (SLNB) is an increasingly standard procedure to help oncologists accur... more Sentinel Lymph Node Biopsy (SLNB) is an increasingly standard procedure to help oncologists accurately stage cancers. It is performed as an alternative to full axillary lymph node dissection in breast cancer patients, reducing the risk of longterm health problems associated with lymph node removal. Intraoperative analysis is currently performed using touchprint cytology, which can introduce significant delay into the procedure. Spectral imaging is forming a multi-plane image where reflected intensities from a number of spectral bands are recorded at each pixel in the spatial plane. We investigate the possibility of using spectral imaging to assess sentinel lymph nodes of breast cancer patients with a view to eventually developing an optical technique that could significantly reduce the time required to perform this procedure. We investigate previously reported spectra of normal and metastatic tissue in the visible and near infrared region, using them as the basis of dummy spectral images. We analyse these images using the spectral angle map (SAM), a tool routinely used in other fields where spectral imaging is prevalent. We simulate random noise in these images in order to determine whether the SAM can discriminate between normal and metastatic pixels as the quality of the images deteriorates. We show that even in cases where noise levels are up to 20% of the maximum signal, the spectral angle map can distinguish healthy pixels from metastatic. We believe that this makes spectral imaging a good candidate for further study in the development of an optical SLNB.
Optical properties of Graphene have recently attracted enormous attention from investigators [1-5... more Optical properties of Graphene have recently attracted enormous attention from investigators [1-5]. A significant amount of work is devoted to the calculation of optical conductivity σ(ω) with the aim of probing the interaction of light with this material. These calculations take the ...
Data set for: Hillier, J. W. et al. (2021). Investigating stability and tunability of quantum dot... more Data set for: Hillier, J. W. et al. (2021). Investigating stability and tunability of quantum dot transport in silicon MOSFETs via the application of electrical stress in IOP Journal of Physics D: Applied Physics
Dataset supports: Liu, F. et al (2018). Manipulation of random telegraph signals in a silicon nan... more Dataset supports: Liu, F. et al (2018). Manipulation of random telegraph signals in a silicon nanowire transistor with a triple gate. Nanotechnology. DOI:10.1088/1361-6528/aadfa6
Zinc sulfide (ZnS) waveguides with the thickness of 0.5 μm have been deposited onto oxidized sili... more Zinc sulfide (ZnS) waveguides with the thickness of 0.5 μm have been deposited onto oxidized silicon wafer substrates at cold temperature (Tcold = –50°C) and ambient temperature (Tambient = 25°C) by thermal evaporation technique. The propagation losses of ZnS waveguides were determined by a scattering detection method. The propagation losses of cold deposited ZnS waveguide were 20.41, 11.35, 3.51 and 2.30 dB/cm measured the wavelengths of 633, 986, 1305 and 1540 nm, respectively. Where as, the propagation losses of ambient deposited ZnS waveguide were 131.50, 47.99, 4.43 and 2.74 dB/cm measured the wavelengths of 633, 986, 1305 and 1540 nm, respectively. The propagation loss of the cold deposited ZnS waveguide was dominated by surface scattering whereas the propagation loss of the ambient deposited ZnS waveguide was dominated by bulk scattering.
Optical fibers are an excellent transmission medium for light and underpin the infrastructure of ... more Optical fibers are an excellent transmission medium for light and underpin the infrastructure of the Internet, but generally after fabrication their optical properties cannot be easily modified. Here, we explore the concept of nanomechanical optical fibers where, in addition to the fiber transmission capability, the internal core structure of the fiber can also be controlled through sub-micron mechanical movements. The nanomechanical functionality of such fibers is demonstrated in the form of dual core optical fibers, in which the cores are independently suspended within the fiber. The movement-based optical change is large compared with traditional electro-optical effects and we show that optical switching of light from one core to the other is achieved through moving one core by just 8 nm.
We observed rotational anisotropy of optical second harmonic generation (SHG) from an array of V-... more We observed rotational anisotropy of optical second harmonic generation (SHG) from an array of V-shaped chromium nanoholes fabricated by electron beam lithography. Phenomenological analysis indicated that the effective nonlinear susceptibility element ð2Þ 313 had a characteristic contribution to the observed anisotropic SHG intensity patterns. Here, coordinate 1 is in the direction of the tip of V shapes in the substrate plane, and 3 indicates the direction perpendicular to the sample surface. The SHG intensity for the S-polarized output light was very weak, probably owing to the cancellation effect of the image dipoles generated at the metal-air boundary. The possible origin of the observed nonlinearity is discussed in terms of the susceptibility elements obtained.
A novel graphene transistor architecture is reported. The transistor has a U-shape geometry and w... more A novel graphene transistor architecture is reported. The transistor has a U-shape geometry and was fabricated using a gallium focused ion beam (FIB). The channel conductance was tuned with a back gate. The I on /I off ratio exceeded 10 5. Introduction: Graphene has ignited tremendous interest since its discovery in 2004[1]. This material is made of a single layer of carbon atoms assembled in a hexagonal structure, providing extraordinary electrical and mechanical properties. The observation of field effect in graphene has particularly attracted the attention of the electron devices community resulting in a large volume of work on graphene field effect transistors (GFET). Indeed graphene is one of the possible materials for the neo silicon era, according to the 2009 International Technology Roadmap for Semiconductor. One outstanding property of graphene is its high carrier mobility at room temperature. In exfoliated supported graphene, mobility as high as 70000 cm 2 V-1 s-1 has been reported [2]. Suspended graphene shows even higher values, reaching 10 6 cm 2 V-1 s-1 as the interaction with the substrate is suppressed [3]. Graphene grown on metals and transferred to a substrate shows lower values. However, large area monolayer or bilayer graphene suffers from the absence of a band gap, which results in poor switching capability of GFETs. Despite the intense work to improve the I on / off ratio, only values less than 100 were achieved. There are two ways used to open a band gap in graphene. The first is to cut it into narrow ribbons (graphene nanoribbons, GNRs). If the width of the ribbon is small enough (few nanometres), carriers are confined in a 1 dimensional quantum wire, resulting in a non-zero band gap. The band gap value is inversely proportional to the width of the
Vanadium doped gallium lanthanum sulphide glass (V:GLS) displays three absorption bands at 580, 7... more Vanadium doped gallium lanthanum sulphide glass (V:GLS) displays three absorption bands at 580, 730 and 1155 nm identified by photoluminescence excitation measurements. Broad photoluminescence, with a full width half maximum (FWHM) of ~500 nm, is observed peaking at 1500 nm when exciting at 514, 808 and 1064 nm. The fluorescence lifetime and quantum efficiency at 300 K were measured to be 33.4 µs and 4% respectively. From the available spectroscopic data we propose the vanadium ions' valence to be 3+ and be in tetrahedral coordination The results indicate potential for development of a laser or optical amplifier based on V:GLS.
ABSTRACTGallium - lanthanum sulphide glasses (GLS) show wide range transparency and low non radia... more ABSTRACTGallium - lanthanum sulphide glasses (GLS) show wide range transparency and low non radiative relaxation rates for dopant ions such as Ho3+, Er3+ etc. They also show permanent photomodification of the refractive index under visible illumination. We report laser ablation deposition of these glasses and preliminary results on film stoichiometry and deposition rate as a function of excimer laser fluence. The sulphur to metal and Ga/La ratios are found to have marked fluence dependencies. The films show considerably more Urbach tail absorption than bulk material. A novel method has been developed for mapping the permanent photomodified index.
Data set for paper: AUTHORS: K. Ibukuro, F. Liu, M. K. Husain, M. Sotto, J. Hillier, Z, Li, I. To... more Data set for paper: AUTHORS: K. Ibukuro, F. Liu, M. K. Husain, M. Sotto, J. Hillier, Z, Li, I. Tomita, Y. Tsuchiya, H. Rutt, and S. Saito. TITLE: Silicon single-electron random number generator based on random telegraph signals at room temperature JOURNAL: AIP Advances
Dataset supports: Ibukuro, K. et al (2018). Random-telegraph-noise and wave-particle duality foun... more Dataset supports: Ibukuro, K. et al (2018). Random-telegraph-noise and wave-particle duality found in a silicon nano-wire. Paper presented at International conference on solid state devices and materials 2018, Tokyo, Japan
Manipulation of carrier densities at the single electron level is inevitable in modern silicon ba... more Manipulation of carrier densities at the single electron level is inevitable in modern silicon based transistors to ensure reliable circuit operation with sufficiently low threshold-voltage variations. However, previous methods required statistical analysis to identify devices which exhibit random telegraph signals (RTSs), caused by trapping and de-trapping of a single electron. Here, we show that we can deliberately introduce an RTS in a silicon nanowire transistor, with its probability distribution perfectly controlled by a triple gate. A quantum dot (QD) was electrically defined in a silicon nanowire transistor with a triple gate, and an RTS was observed when two barrier gates were negatively biased to form potential barriers, while the entire nanowire channel was weakly inverted by the top gate. We could successfully derive the energy levels in the QD from the quantum mechanical probability distributions and the average lifetimes of RTSs. This study reveals that we can manipulate individual electrons electrically, even at room temperature, and paves the way to use a charged state for quantum technologies in the future.
Zinc sulfide thin films with the thickness of about 0.5 µm were deposited using a thermal evapora... more Zinc sulfide thin films with the thickness of about 0.5 µm were deposited using a thermal evaporation system onto oxidized silicon substrates at cold temperature (Tcold = -50°C) and at ambient temperature (Tambient = 25°C). A special substrate holder with a thermoelectric cooler was used to cool the substrates. The crystalline structure and the morphology of the films were investigated by X-Ray Diffraction and atomic force microscopy, respectively. XRD results show that the structure of the cold deposited ZnS thin film was completely amorphous. The ambient deposited ZnS thin film has a mixture of amorphous structure and polycrystalline structure with the preference orientation of (111) plane. The crystallite size of ambient deposited ZnS thin film was about 10 nm as calculated using the Scherrer formula. The AFM analysis revealed that the estimated grain size of cold deposited and ambient deposited ZnS were about 360 nm and 1220 nm, respectively. The surface roughness of the cold de...
Laser action in Neodymium doped inorganic aprotic solvents POC13 and Se0C12 has been known forman... more Laser action in Neodymium doped inorganic aprotic solvents POC13 and Se0C12 has been known formany years, but there has been little work in this field recently. Very little work has been reportedon ions other than Nd3+. The ability to readily change the dopant, vary concentrations, add co-dopantsetc at low cost is attractive, and using modern laser techniques it is possible that these materialsmight again be useful. In particular there are a variety of possible solvents which have not beenexploited to date which offer the possibility of tailoring the non-radiative rates of the various levelsfor the particular transition required.
IEEE Transactions on Geoscience and Remote Sensing
Passive millimeter-wave (PMMW) imaging has been used for several close-range applications such as... more Passive millimeter-wave (PMMW) imaging has been used for several close-range applications such as personal security checks, scene monitoring, and so on. PMMW images contain a variety of types of image edges which represent intensity discontinuities. As a special edge, an object contour edge is an important feature for object detection and recognition, which denotes the external shape of the object. In this article, a physically based contour edge display method using adjustable linear polarization ratio (ALPR) by multipolarization imaging is proposed. Polarization brightness temperature (TB) models of the object and radiometer observation are built. According to the physical principle of edge generation, the ALPR properties of the contour edge are investigated. By fusing multipolarization information, the simple feature parameter ALPR is sensitive to the object contour edge. Then, the specific operation process of the proposed method based on multipolarization images is presented. Simulations and measurements of polarimetric imaging for personal security inspection scenes were conducted to verify the contour edge display performance. Finally, the applicability of the method is discussed and summarized.
We report the successful fabrication of a new type of dual core fiber, comprising 2 optical cores... more We report the successful fabrication of a new type of dual core fiber, comprising 2 optical cores suspended in air. The cores are sub-micron in size, each held in place by 2 thin glass membranes attached to the cladding. The successful realisation of this fiber should open up a range of interesting applications in a variety of different areas.
The need for hardware random number generators (HRNGs) that can be integrated in a silicon (Si) c... more The need for hardware random number generators (HRNGs) that can be integrated in a silicon (Si) complementarymetal-oxide-semiconductor (CMOS) platform has become increasingly important in the era of the Internet-of-Things (IoT). Si MOSFETs exhibiting random telegraph signals (RTSs) have been considered as such a candidate for HRNG, though its application has been hindered by RTS's variability and uncontrollable, unpredictable characteristics. In this paper, we report the generation and randomness evaluation of random numbers from RTSs in a Si single electron pump (SEP) device at room temperature. SEP devices are known to consistently produce RTSs due to a quantum dot electrically defined by multi-layer polycrystalline Si gates. Using RTSs observed in our devices, random numbers were extracted by a classifier supported by supervised learning, where part of data was used to train the classifier before it is applied to the rest to generate random numbers. The random numbers generated from RTSs were used as inputs for the Monte Carlo method to calculate the values of π, and the distribution was compared against the result obtained from the Mersenne Twister, a representative pseudo-random number generator (PRNG), under the same condition. π was estimated more than 80 000 times, and the distribution of the estimated values has a central value of 3.14 with a variance of 0.273, which is only twice as large as the result from PRNG. Our result paves a way to fully electronic CMOS compatible HRNGs that can be integrated in a modern system-on-a-chip in IoT devices.
Germanium (Ge) is a promising candidate for a CMOS compatible laser diode. This is due to its com... more Germanium (Ge) is a promising candidate for a CMOS compatible laser diode. This is due to its compatibility with Silicon (Si) and its ability to be converted into a direct band gap material by applying tensile strain. In particular uniaxial suspended Ge bridges have been extensively explored due to their ability to introduce high tensile strain. There have been two recent demonstrations of low-temperature optically-pumped lasing in these bridges but no room temperature operation accredit to insufficient strain and poor thermal management. In this paper we compare uniaxial bridges with polyaxial bridges in terms of mechanical stress and thermal management using Finite Element Modelling (FEM). The stress simulations reveal that polyaxial bridges suffer from extremely large corner stresses which prevent larger strain from being introduced compared with uniaxial bridges. Thermal simulations however reveal that they are much less thermally sensitive than uniaxial bridges which may indicate lower optical losses. Bridges were fabricated and Raman spectroscopy was used to validate the results of the simulations. We postulate that polyaxial bridges could offer many advantages over their uniaxial counterparts as potential laser devices
Sentinel Lymph Node Biopsy (SLNB) is an increasingly standard procedure to help oncologists accur... more Sentinel Lymph Node Biopsy (SLNB) is an increasingly standard procedure to help oncologists accurately stage cancers. It is performed as an alternative to full axillary lymph node dissection in breast cancer patients, reducing the risk of longterm health problems associated with lymph node removal. Intraoperative analysis is currently performed using touchprint cytology, which can introduce significant delay into the procedure. Spectral imaging is forming a multi-plane image where reflected intensities from a number of spectral bands are recorded at each pixel in the spatial plane. We investigate the possibility of using spectral imaging to assess sentinel lymph nodes of breast cancer patients with a view to eventually developing an optical technique that could significantly reduce the time required to perform this procedure. We investigate previously reported spectra of normal and metastatic tissue in the visible and near infrared region, using them as the basis of dummy spectral images. We analyse these images using the spectral angle map (SAM), a tool routinely used in other fields where spectral imaging is prevalent. We simulate random noise in these images in order to determine whether the SAM can discriminate between normal and metastatic pixels as the quality of the images deteriorates. We show that even in cases where noise levels are up to 20% of the maximum signal, the spectral angle map can distinguish healthy pixels from metastatic. We believe that this makes spectral imaging a good candidate for further study in the development of an optical SLNB.
Optical properties of Graphene have recently attracted enormous attention from investigators [1-5... more Optical properties of Graphene have recently attracted enormous attention from investigators [1-5]. A significant amount of work is devoted to the calculation of optical conductivity σ(ω) with the aim of probing the interaction of light with this material. These calculations take the ...
Data set for: Hillier, J. W. et al. (2021). Investigating stability and tunability of quantum dot... more Data set for: Hillier, J. W. et al. (2021). Investigating stability and tunability of quantum dot transport in silicon MOSFETs via the application of electrical stress in IOP Journal of Physics D: Applied Physics
Dataset supports: Liu, F. et al (2018). Manipulation of random telegraph signals in a silicon nan... more Dataset supports: Liu, F. et al (2018). Manipulation of random telegraph signals in a silicon nanowire transistor with a triple gate. Nanotechnology. DOI:10.1088/1361-6528/aadfa6
Zinc sulfide (ZnS) waveguides with the thickness of 0.5 μm have been deposited onto oxidized sili... more Zinc sulfide (ZnS) waveguides with the thickness of 0.5 μm have been deposited onto oxidized silicon wafer substrates at cold temperature (Tcold = –50°C) and ambient temperature (Tambient = 25°C) by thermal evaporation technique. The propagation losses of ZnS waveguides were determined by a scattering detection method. The propagation losses of cold deposited ZnS waveguide were 20.41, 11.35, 3.51 and 2.30 dB/cm measured the wavelengths of 633, 986, 1305 and 1540 nm, respectively. Where as, the propagation losses of ambient deposited ZnS waveguide were 131.50, 47.99, 4.43 and 2.74 dB/cm measured the wavelengths of 633, 986, 1305 and 1540 nm, respectively. The propagation loss of the cold deposited ZnS waveguide was dominated by surface scattering whereas the propagation loss of the ambient deposited ZnS waveguide was dominated by bulk scattering.
Optical fibers are an excellent transmission medium for light and underpin the infrastructure of ... more Optical fibers are an excellent transmission medium for light and underpin the infrastructure of the Internet, but generally after fabrication their optical properties cannot be easily modified. Here, we explore the concept of nanomechanical optical fibers where, in addition to the fiber transmission capability, the internal core structure of the fiber can also be controlled through sub-micron mechanical movements. The nanomechanical functionality of such fibers is demonstrated in the form of dual core optical fibers, in which the cores are independently suspended within the fiber. The movement-based optical change is large compared with traditional electro-optical effects and we show that optical switching of light from one core to the other is achieved through moving one core by just 8 nm.
We observed rotational anisotropy of optical second harmonic generation (SHG) from an array of V-... more We observed rotational anisotropy of optical second harmonic generation (SHG) from an array of V-shaped chromium nanoholes fabricated by electron beam lithography. Phenomenological analysis indicated that the effective nonlinear susceptibility element ð2Þ 313 had a characteristic contribution to the observed anisotropic SHG intensity patterns. Here, coordinate 1 is in the direction of the tip of V shapes in the substrate plane, and 3 indicates the direction perpendicular to the sample surface. The SHG intensity for the S-polarized output light was very weak, probably owing to the cancellation effect of the image dipoles generated at the metal-air boundary. The possible origin of the observed nonlinearity is discussed in terms of the susceptibility elements obtained.
A novel graphene transistor architecture is reported. The transistor has a U-shape geometry and w... more A novel graphene transistor architecture is reported. The transistor has a U-shape geometry and was fabricated using a gallium focused ion beam (FIB). The channel conductance was tuned with a back gate. The I on /I off ratio exceeded 10 5. Introduction: Graphene has ignited tremendous interest since its discovery in 2004[1]. This material is made of a single layer of carbon atoms assembled in a hexagonal structure, providing extraordinary electrical and mechanical properties. The observation of field effect in graphene has particularly attracted the attention of the electron devices community resulting in a large volume of work on graphene field effect transistors (GFET). Indeed graphene is one of the possible materials for the neo silicon era, according to the 2009 International Technology Roadmap for Semiconductor. One outstanding property of graphene is its high carrier mobility at room temperature. In exfoliated supported graphene, mobility as high as 70000 cm 2 V-1 s-1 has been reported [2]. Suspended graphene shows even higher values, reaching 10 6 cm 2 V-1 s-1 as the interaction with the substrate is suppressed [3]. Graphene grown on metals and transferred to a substrate shows lower values. However, large area monolayer or bilayer graphene suffers from the absence of a band gap, which results in poor switching capability of GFETs. Despite the intense work to improve the I on / off ratio, only values less than 100 were achieved. There are two ways used to open a band gap in graphene. The first is to cut it into narrow ribbons (graphene nanoribbons, GNRs). If the width of the ribbon is small enough (few nanometres), carriers are confined in a 1 dimensional quantum wire, resulting in a non-zero band gap. The band gap value is inversely proportional to the width of the
Vanadium doped gallium lanthanum sulphide glass (V:GLS) displays three absorption bands at 580, 7... more Vanadium doped gallium lanthanum sulphide glass (V:GLS) displays three absorption bands at 580, 730 and 1155 nm identified by photoluminescence excitation measurements. Broad photoluminescence, with a full width half maximum (FWHM) of ~500 nm, is observed peaking at 1500 nm when exciting at 514, 808 and 1064 nm. The fluorescence lifetime and quantum efficiency at 300 K were measured to be 33.4 µs and 4% respectively. From the available spectroscopic data we propose the vanadium ions' valence to be 3+ and be in tetrahedral coordination The results indicate potential for development of a laser or optical amplifier based on V:GLS.
ABSTRACTGallium - lanthanum sulphide glasses (GLS) show wide range transparency and low non radia... more ABSTRACTGallium - lanthanum sulphide glasses (GLS) show wide range transparency and low non radiative relaxation rates for dopant ions such as Ho3+, Er3+ etc. They also show permanent photomodification of the refractive index under visible illumination. We report laser ablation deposition of these glasses and preliminary results on film stoichiometry and deposition rate as a function of excimer laser fluence. The sulphur to metal and Ga/La ratios are found to have marked fluence dependencies. The films show considerably more Urbach tail absorption than bulk material. A novel method has been developed for mapping the permanent photomodified index.
Data set for paper: AUTHORS: K. Ibukuro, F. Liu, M. K. Husain, M. Sotto, J. Hillier, Z, Li, I. To... more Data set for paper: AUTHORS: K. Ibukuro, F. Liu, M. K. Husain, M. Sotto, J. Hillier, Z, Li, I. Tomita, Y. Tsuchiya, H. Rutt, and S. Saito. TITLE: Silicon single-electron random number generator based on random telegraph signals at room temperature JOURNAL: AIP Advances
Dataset supports: Ibukuro, K. et al (2018). Random-telegraph-noise and wave-particle duality foun... more Dataset supports: Ibukuro, K. et al (2018). Random-telegraph-noise and wave-particle duality found in a silicon nano-wire. Paper presented at International conference on solid state devices and materials 2018, Tokyo, Japan
Manipulation of carrier densities at the single electron level is inevitable in modern silicon ba... more Manipulation of carrier densities at the single electron level is inevitable in modern silicon based transistors to ensure reliable circuit operation with sufficiently low threshold-voltage variations. However, previous methods required statistical analysis to identify devices which exhibit random telegraph signals (RTSs), caused by trapping and de-trapping of a single electron. Here, we show that we can deliberately introduce an RTS in a silicon nanowire transistor, with its probability distribution perfectly controlled by a triple gate. A quantum dot (QD) was electrically defined in a silicon nanowire transistor with a triple gate, and an RTS was observed when two barrier gates were negatively biased to form potential barriers, while the entire nanowire channel was weakly inverted by the top gate. We could successfully derive the energy levels in the QD from the quantum mechanical probability distributions and the average lifetimes of RTSs. This study reveals that we can manipulate individual electrons electrically, even at room temperature, and paves the way to use a charged state for quantum technologies in the future.
Zinc sulfide thin films with the thickness of about 0.5 µm were deposited using a thermal evapora... more Zinc sulfide thin films with the thickness of about 0.5 µm were deposited using a thermal evaporation system onto oxidized silicon substrates at cold temperature (Tcold = -50°C) and at ambient temperature (Tambient = 25°C). A special substrate holder with a thermoelectric cooler was used to cool the substrates. The crystalline structure and the morphology of the films were investigated by X-Ray Diffraction and atomic force microscopy, respectively. XRD results show that the structure of the cold deposited ZnS thin film was completely amorphous. The ambient deposited ZnS thin film has a mixture of amorphous structure and polycrystalline structure with the preference orientation of (111) plane. The crystallite size of ambient deposited ZnS thin film was about 10 nm as calculated using the Scherrer formula. The AFM analysis revealed that the estimated grain size of cold deposited and ambient deposited ZnS were about 360 nm and 1220 nm, respectively. The surface roughness of the cold de...
Laser action in Neodymium doped inorganic aprotic solvents POC13 and Se0C12 has been known forman... more Laser action in Neodymium doped inorganic aprotic solvents POC13 and Se0C12 has been known formany years, but there has been little work in this field recently. Very little work has been reportedon ions other than Nd3+. The ability to readily change the dopant, vary concentrations, add co-dopantsetc at low cost is attractive, and using modern laser techniques it is possible that these materialsmight again be useful. In particular there are a variety of possible solvents which have not beenexploited to date which offer the possibility of tailoring the non-radiative rates of the various levelsfor the particular transition required.
IEEE Transactions on Geoscience and Remote Sensing
Passive millimeter-wave (PMMW) imaging has been used for several close-range applications such as... more Passive millimeter-wave (PMMW) imaging has been used for several close-range applications such as personal security checks, scene monitoring, and so on. PMMW images contain a variety of types of image edges which represent intensity discontinuities. As a special edge, an object contour edge is an important feature for object detection and recognition, which denotes the external shape of the object. In this article, a physically based contour edge display method using adjustable linear polarization ratio (ALPR) by multipolarization imaging is proposed. Polarization brightness temperature (TB) models of the object and radiometer observation are built. According to the physical principle of edge generation, the ALPR properties of the contour edge are investigated. By fusing multipolarization information, the simple feature parameter ALPR is sensitive to the object contour edge. Then, the specific operation process of the proposed method based on multipolarization images is presented. Simulations and measurements of polarimetric imaging for personal security inspection scenes were conducted to verify the contour edge display performance. Finally, the applicability of the method is discussed and summarized.
We report the successful fabrication of a new type of dual core fiber, comprising 2 optical cores... more We report the successful fabrication of a new type of dual core fiber, comprising 2 optical cores suspended in air. The cores are sub-micron in size, each held in place by 2 thin glass membranes attached to the cladding. The successful realisation of this fiber should open up a range of interesting applications in a variety of different areas.
The need for hardware random number generators (HRNGs) that can be integrated in a silicon (Si) c... more The need for hardware random number generators (HRNGs) that can be integrated in a silicon (Si) complementarymetal-oxide-semiconductor (CMOS) platform has become increasingly important in the era of the Internet-of-Things (IoT). Si MOSFETs exhibiting random telegraph signals (RTSs) have been considered as such a candidate for HRNG, though its application has been hindered by RTS's variability and uncontrollable, unpredictable characteristics. In this paper, we report the generation and randomness evaluation of random numbers from RTSs in a Si single electron pump (SEP) device at room temperature. SEP devices are known to consistently produce RTSs due to a quantum dot electrically defined by multi-layer polycrystalline Si gates. Using RTSs observed in our devices, random numbers were extracted by a classifier supported by supervised learning, where part of data was used to train the classifier before it is applied to the rest to generate random numbers. The random numbers generated from RTSs were used as inputs for the Monte Carlo method to calculate the values of π, and the distribution was compared against the result obtained from the Mersenne Twister, a representative pseudo-random number generator (PRNG), under the same condition. π was estimated more than 80 000 times, and the distribution of the estimated values has a central value of 3.14 with a variance of 0.273, which is only twice as large as the result from PRNG. Our result paves a way to fully electronic CMOS compatible HRNGs that can be integrated in a modern system-on-a-chip in IoT devices.
Germanium (Ge) is a promising candidate for a CMOS compatible laser diode. This is due to its com... more Germanium (Ge) is a promising candidate for a CMOS compatible laser diode. This is due to its compatibility with Silicon (Si) and its ability to be converted into a direct band gap material by applying tensile strain. In particular uniaxial suspended Ge bridges have been extensively explored due to their ability to introduce high tensile strain. There have been two recent demonstrations of low-temperature optically-pumped lasing in these bridges but no room temperature operation accredit to insufficient strain and poor thermal management. In this paper we compare uniaxial bridges with polyaxial bridges in terms of mechanical stress and thermal management using Finite Element Modelling (FEM). The stress simulations reveal that polyaxial bridges suffer from extremely large corner stresses which prevent larger strain from being introduced compared with uniaxial bridges. Thermal simulations however reveal that they are much less thermally sensitive than uniaxial bridges which may indicate lower optical losses. Bridges were fabricated and Raman spectroscopy was used to validate the results of the simulations. We postulate that polyaxial bridges could offer many advantages over their uniaxial counterparts as potential laser devices
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Papers by Harvey Rutt