Conveners
Photonics: Photonics in Biology
- Pieter Neethling (Laser Research Institute, University of Stellenbosch)
Photonics: Quantum Aspects
- Gurthwin Bosman (Stellenbosch University)
Photonics: Quantum phenomena
- Andrew Forbes (U. Witwatersrand)
Photonics: Sensing
- Tjaart Krüger (University of Pretoria)
Photonics: Non Specialist Session
- Andrew Forbes (U. Witwatersrand)
Photonics: Biological applications
- Pieter Neethling (Laser Research Institute, University of Stellenbosch)
Photonics: Spectroscopy, communication and beam shaping
- Mitchell Cox (University of the Witwatersrand)
Photonics
- There are no conveners in this block
Photonics
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Photonics
- There are no conveners in this block
Photonics
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Photonics
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G Kah, R Chandran and H Abrahamse
Laser Research Centre, Faculty of Health Sciences, University of Johannesburg, P.O. Box 17011, Doornfontein 2028, South Africa.
Email: rahulc@uj.ac.za
Abstract. Worldwide, lung cancer remains the main cause of malignant tumours and it contributes to a high mortality rate in cancer cases. Conventional therapeutic approaches for lung cancer are...
Cancer has been established as one of the prevalent causes of death globally, rating second after cardiovascular disease. The GLOBOCAN 2020 report has estimated global new cancer cases of approximately 19.3 million, with a death toll of nearly 10.0 million. The report also estimates about 2.3 million of new cases of female breast malignancy, making it the most commonly diagnosed cancer type....
Matrix-vector multiplication is a crucial operation in quantum algorithms such as Deutsch-Josza's, Grover’s, and phase estimation. Here we present an approach that uses classical light to perform similar operations. We demonstrate this technique by directing light onto pixelated liquid crystal Spatial Light Modulators (SLMs) that encode information on the spatial pattern of light to create a...
True random numbers are ubiquitous in cryptography, simulation and many other information processing tasks. Here we experimentally demonstrate quantum random number generation with an on-chip linear plasmonic beamsplitter. The beamsplitter has a footprint of 2$\mu$m x 10$\mu$m and is more compact than a previous demonstration, with a reduction in size by a factor of 2, thereby reducing the...
Karl Popper, a philosopher, had found the entanglement of particles fascinating. He wanted to test the standard interpretation of quantum mechanics since he believed that knowledge of one of the entangled particles should not affect the properties of the other entangled particle, as well as investigating the presence of a non-local influence in these systems. The behaviour of a quantum...
High-dimensional quantum states, known as qudits, have the potential to enhance the performance of quantum information systems. One promising approach for devising and delivering qudits is to exploit the multiple modes of a few-mode fiber (FMF) as the carriers of the quantum states. In this work, we show the excitation, transmission and detection of wavelength-entangled photons in a few-mode...
In the extremes of quantum and classical states of light we find quantum-like light, coherent states that look like particles but behave like waves. Here we present a novel laser that exhibits quantum (wave) and ray (particle) like features. We build the laser cavity using simple linear optical elements and show that the relation between the cavity length(L) and radius of curvature(R) when...
Vectorial light has long been established as a robust analogy for 2-dimensional quantum systems. Consequently, many of the insights and techniques from quantum mechanics, and entanglement in particular, have found significant applications in helping us understand and quantify many properties of vectorial light. This relationship also allows us to probe the nature of quantum systems using...
Vector beams are characterized by their non-separable (entangled) polarisation and spatial degrees of freedom. However, different views persist on the entanglement’s robustness against phase-perturbing turbulent media: on one hand the entanglement should be robust, on the other it decays. This work is aimed at reconciling the two contradictions, by experimentally and theoretically studying...
The COVID-19 pandemic has highlighted the urgent need for rapid and sensitive diagnostic tools to enable effective monitoring and control of the disease. In this study, we present an approach to COVID-19 detection by employing quantum phase-based surface plasmon resonance biosensing, which improves the limit of detection (LOD) compared to its classical equivalent. We demonstrate a theoretical...
Mycobacterium tuberculosis (Mtb) is an intracellular pathogen that has evolved defense mechanisms to evade the human immune response, allowing it to persist indefinitely in the host. The bacterium primarily targets the human lungs and produces the contagious disease tuberculosis (TB). Although the bacteria attack the lungs, TB can spread to other parts of the body such as the kidneys, bones,...
Over the last three decades, biosensors based on photonic crystals (PhCs) have been developed and continue to receive significant recognition owing to their distinctive electromagnetic properties and broad applications. Studies that have used refractive index as a parameter to design optical biosensing devices based on PhCs have resulted in optical devices that are sensitive with quick...
Quantum physics may be at the origin of tomorrow's microscopes - let's understand how it works!
Quantum imaging harnesses quantum properties of light to go beyond the limits of classical imaging. In this respect, entangled photons sources are very promising. They have been proposed and used to achieve super-resolution and sub-shot-noise imaging, and to create new imaging approaches such...
Frequency conversion of light with orbital angular momentum (OAM) such as Laguerre-Gaussian (LG) beams is important for various applications such as free-space optical communications, sensitive infrared light detection, and obtaining OAM lasers. Traditional methods of frequency conversion involve a nonlinear medium and two input beams i.e., a signal LG beam and a pump beam with either flat-top...
Optical Tweezers have become a popular tool for manipulating micron diameter particles with minimal influence on the properties of said particles. By using a single laser and a high numerical aperture lens, these particles can easily be confined and moved for the researcher’s purpose. Such manipulation allows for the measurement of piconewton forces, which makes it possible to measure the...
Single-molecule spectroscopy (SMS) has proven to be a powerful technique for investigating structure-function relationships in light-harvesting systems. In particular, SMS has unraveled dynamics in light-harvesting complexes that are hidden in ensemble measurements. However, the environment used in SMS experiments is a poor representation of the natural cellular environment, and therefore the...
During the initial stage of photosynthesis, sunlight is absorbed by molecular light-harvesting complexes. The technique of linear optical spectroscopy is a powerful tool to study these complexes. In principle, all the information contained in an experimental linear spectrum can be extracted through comparison with the corresponding modelled spectrum—provided that the modelling is accurate. In...
Poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)], PCDTBT, is a conjugated donor polymer used in low bandgap organic solar cells (OSCs). OSC efficiencies decrease when exposed to light, oxygen, or water. The effects of various excessive light conditions on degrading dilute PCDTBT in solution are investigated in this work. A custom photodegradation...
We report the simulation of ultrafast pulse evolution along a silicon germanium waveguide. Pulse evolution of 205 fs duration and 2.35 kW peak power at 4.15 μm propagating through a 5 cm long silicon germanium on silicon substrate waveguide was simulated by solving the generalised nonlinear Schrödinger equation using the fourth order Runge-Kutta in the interaction picture method. Coherent...
Free space optical communication has the potential to mitigate the existing digital divide. However, it is highly susceptible to atmospheric turbulence, especially when used with mode division multiplexing. Turbulence decreases the received power of the transmitted laser beam, thus inducing errors. By simultaneously transmitting and/or receiving two modes, the received power could be improved....
Entanglement between photons has been a source of great interest in the past few decades being the catalyst for fundamental tests of quantum mechanics and offering a plethora of applications from ghost imaging to quantum key distribution. However, these entangled photon states are highly susceptible to environmental disturbances, thus requiring mechanisms for robustness in harsher...
This research is dedicated to the development of a cost-effective Free Space Optical (FSO) system using standard telecom fibre cables. These cables, which include the single-mode and five multimode fibre cables (OM1, OM2, OM3, OM4, and OM5), are selected for their wide availability and cost-effectiveness. This study assesses the coupling performance of these fibre cables in the presence of...
