Physics

Fast scanning system for Optical Coherence Tomography

Supervisor

Frédérique Vanholsbeeck
Sylwia Kolenderska

Discipline

Physics

Project code: SCI124

Optical Coherence Tomography (OCT) is a high-resolution 3D imaging technique based on white-light interferometry. To be able to provide high-quality images in real time, the OCT experimental systems require fast scanning setups synchronized with the optical detectors and laser sources.

The student needs to possess basic programming skills in LabVIEW to be able to communicate with optical scanners and synchronize their work with either a camera or a photodiode. Also, this project will involve careful reading of instruction manuals for various scientific instruments, including the architecture of line-scan cameras, high-power laser sources and dual-balance photodiodes.

Write/modify a python scrip to communicate between an optical imaging system sand DAQ card

Supervisor

Frédérique Vanholsbeeck

Discipline

Physics

Project code: SCI125

Optical Coherence Tomography (OCT) is a high-resolution 3D imaging technique based on white-light interferometry. To be able to provide high-quality images in real time, the OCT experimental systems require fast scanning galvanometer scanners synchronized with the optical detectors and laser sources.

Your task is to modify/write a new python code to speed up the system, and improve communication between the trigger clock signals and the DAQ card. If times allows it, create a user interface.

The student needs programming skills in python to achieve the aim. Also, this project will involve careful reading of instruction manuals for various scientific instruments, including the architecture of balanced detectors, high-power laser sources and DAQ card.

Tissue differentiation using in vivo biomedical imaging

Supervisor

Dr Frédérique Vanholsbeeck

Discipline

Physics

Project code: SCI126

This project is based on optical coherence tomography (OCT), an interferometric technique that allows high resolution in vivo imaging. The student will learn about the technique of OCT and how to analyse images to extract more information than just the structure of the sample. For example, information on the sample can be extracted using the Doppler effect or the image speckle. Information such as sample birefringence, elastic properties and so on can be obtained. Here we aim at measuring tissue dispersive properties to differentiate tissue. Ultimately, this work aims at performing in vivo biopsy.

Near real-time bacterial monitoring

Supervisor

Cushla McGoverin
Frederique Vanholsbeeck

Discipline

Physics

Project code: SCI127

The optrode is an all fibre spectroscopic near-real time system able to detect low levels of light upon optical excitation. We are using this system to monitor bacterial growth and enumerate tagged bacteria.

This project will be about enumerating and bacteria using the optrode and different experimental conditions, e.g. fluorescent stain, species of bacteria. The student will learn about microfluidic, fluorescence, and microbiology.

Near real-time bacterial differentation

Supervisor

Cushla McGoverin
Frederique Vanholsbeeck

Discipline

Physics

Project code: SCI128

The optrode is an all fibre spectroscopic near-real time system able to detect low levels of light upon optical excitation. We are using this system to monitor bacterial growth and enumerate tagged bacteria.

This project will be about enumerating and differentiating bacteria using the optrode and different experimental conditions, e.g. fluorescent stain, species of bacteria. The student will learn about microfluidic, fluorescence, machine learning and microbiology.

Dynamic Microfluidics Experiments: Drop Impacts and Capillarity

Supervisor

Geoff Willmott
Steve Wells
Miguel Balzan

Discipline

Physics

Project code: SCI129

Experimental projects are available to study microscale liquid dynamics using high-speed photography (producing cool slow-motion videos). We are particularly interested in drop impact experiments, in which drops collide with solid surfaces. Fluids of interest include partially dried dairy products, and ferrofluids which produce ‘spiky’ magnetic instabilities. Surfaces may be patterned in order to control the spreading, splashing and rebounding of the drops. A project could also focus on development of image analysis techniques.

Projects are suitable for students from any quantitative science / engineering background, and can be aligned with industrial (real-world) applications. Skills developed will include experimental methods for materials science, and understanding of fluid dynamics.

Nanofluidics and Active Matter (Theory / Modelling)

Supervisor

Geoff Willmott

Discipline

Physics

Project code: SCI130

Project(s) will develop and use computational and/or theoretical models in the fields of (i) nanofluidics or (ii) active matter. In nanofluidics, liquids are confined to spaces on nanometre length scales. Modelling will be used to guide experimentalists working with nanopores and nanopipettes. Active matter involves collections of interacting, moving particles such as swarms and flocks. Here, the system to be studied is a large collection of asymmetric ‘Janus’ nanoparticles. Especially suitable for students with some computational / numerical experience.

Monsoon and rivers: the freshwater feedback

Supervisor

Gilles Bellon

Discipline

Physics

Project code: SCI131

Big South Asian rivers such as the Ganges, Brahmaputra and Irrawady discharge a large amount of freshwater in the Bay of Bengal. As freshwater is lighter than seawater, river discharge forms a layer of water at the surface that does not mix with the underlying ocean. The summer sun efficiently warms this layer and evaporation ensues. The evaporated water vapour feeds precipitating systems that propagate over land and reinforce the monsoon rains and atmospheric circulation. These rains increase the rivers flowrate and consequently their discharge in the ocean. This chain of mechanisms forms a positive feedback which is yet to be studied.

This project will be the first to investigate this feedback using a state-of-the-art climate model. By analysing the differences between three simulations, in which river discharge is switched on, imposed, or switched off, we will evaluate its impact on the South Asian monsoon.

Skills in computer data analysis will be useful.

Biomedical Photoacoustic and Ultrasonic Imaging

Supervisor

Jami Shepherd
Kasper van Wijk

Discipline

Physics

Project code: SCI132

Student projects are available in biomedical ultrasound (US) or photoacoustic (PA) imaging. Both imaging techniques use non-ionizing (safe) waves to image several centimetres deep in the human body non-invasively. While US is sensitive to differences in mechanical properties (e.g. stiffness, density, etc.), PA imaging probes optical properties. The hemoglobin in our blood exhibits especially strong optical contrast, therefore PA imaging is well-suited to visualising veins and arteries. Projects are available for laboratory experiments, numerical modelling, and/or image processing, depending on the interests of the student.

Potential topics include

  • optimisation of experimental setup for real-time photoacoustic imaging
  • sensing blood flow with photoacoustic Doppler imaging
  • filter design and optimisation for photoacoustic Doppler imaging
  • modelling wave propagation in tissue to better reconstruct ultrasound and photoacoustic images

Ideally students will have high-level programming experience (e.g. MATLAB and/or Python).

CURVEPOPS: Modelling supernova lightcurves

Supervisor

JJ Eldridge

Discipline

Physics

Project code: SCI133

The project will involve comparing numerical models of supernovae, exploding stars, to those that have been observed in other galaxies. The supernovae that will be used will include events where the progenitor star was observed before the explosion. The main point of the project is to see if the same model can reproduce the appearance of the star before it exploded as well as the details of the explosion itself. Skills required are coding skills (e.g. python).

How the sounds of whales and the earth may tell us about climate change

Supervisor

Kasper van wijk

Discipline

Physics

Project code: SCI134

Whales can communicate over great distances by singing into a “channel” in the oceans called SOFAR. This channel is a waveguide set up by just the right temperature, pressure and salinity conditions. As climate changes, so may the conditions that make up the SOFAR channel. In this project, we will look for and analyse sound propagating in the SOFAR channel not generated by whales, but by earthquakes. In the process, we’ll try to answer what are the conditions for generation of these so-called T-waves (source location, mechanism, and magnitude, for example).

Gas sensing with Si Terahertz (THz) micro-resonators

Supervisor

Assoc Prof R Leonhardt
Dominik Vogt

Discipline

Physics

Project code: SCI135

Whispering-gallery mode resonators (WGMRs) for terahertz (THz) radiation is a cutting-edge research topic. Numerical modeling of such resonators is essential to fully exploit their potentialas as they can be used , e.g., to predict the optimal shape. The aim of this project is to provide simulations to support the experimental work performed in the THz Lab. The student will be using Mie scattering as well as sophisticated simulation packages to model the WGMRs. The majority of the simulations are performed on a supercomputer. Good programming skills, e.g. in Python or Matlab, are essential.

Simulation of integrated Terahertz (THz) components

Supervisor

Assoc Prof R Leonhardt
Dominik Vogt

Discipline

Physics

Project code: SCI136

THz radiation (0.5THz=0.6mm) will at some stage replace the current systems (~30GHz) to enable ultra-fast WiFi. To do so, circuits based on Si technology that can handle THz radiation have to be developed. This project is aimed at designing relatively simple components like waveguides, splitters, and filters for this new technology. The simulations will be mainly performed using the commercial sofware COMSOL. The challenge will be to limit the computing time for these 3D simulations. Initially some calculations will be performed in 2D to get an overview about different approaches. The overall aim is to design a ‘circuit’ that can be implemented on a Si wafer, and then used for characterisation in our THz Lab. If you are interested, contact me for a tour of our lab.

Design and implementation of novel Terahertz (THz) micro-resonators

Supervisor

Assoc Prof R Leonhardt
Dominik Vogt

Discipline

Physics

Project code: SCI137

High quality (Q) factor THz resonators that work by total internal reflection are a recent development in THz spectroscopy. Because of the large wavlength (0.5THz=0.6mm), the concepts/possibilities are different to resonators used in the visible or IR region. Up-to-now only very simple designs like a ‘sphere’ and a ‘disc’ have been studied. One aim is to find a design that results in even higher Q factors. In the project you will explore different designs (e.g. ‘double disc’) numerically, and if a design looks promising you will implement it, and experimentally characterise it using the sophisticated set-up in the THz Lab. This project will therefore be a mixture of simulations and experimental work. If you are interested, contact me for a tour of our lab.

Spin-Orbit Coupled Bose Einstein condensates in 2D Lattices

Supervisor

Dr Maarten Hoogerland

Discipline

Physics

Project code: SCI138

Bose Einstein condensation (BEC) is a form of matter in which an ensemble of bosons share a common mesoscopic wavefunction. BECs are a versatile tool for creating analogies to other physical systems. The advantage of using BECs is that the system parameters are highly tunable, which is not necessarily the case in, for example, condensed matter systems. For instance, we can simulate spin-orbit coupling (SOC), is a quantum phenomenon in which the spin of a particle is tied to its momentum. The project will involve the student assisting with running experiments and collecting data.

Sensing DC electric fields with Rydberg atoms

Supervisor

Dr Maarten Hoogerland
Professor Neil Broderick

Discipline

Physics

Project code: SCI139

Detecting DC electric fields is not a trivial task, as any sensor may modify the field it is trying to measure. Recently, some progress has been mode using “Rydberg” atoms, which are atoms in a highly excited state, as antennas for a DC electric field. The electric field changes the resonance frequency in these atoms. The project involves designing, building and testing a sensor based on this technique.

Chat line for atoms

Supervisor

Dr Maarten Hoogerland

Discipline

Physics

Project code: SCI140

We use optical fibres, drawn out to a diameter of less than the wavelength of light, to interface single photons of light with single atoms, trapped on the surface of the fibre. The project involves using our existing setup, improving the coupling between photons and atoms.

Chimera-like states in nonlinear optics

Supervisor

Dr Miro Erkintalo

Discipline

Physics

Project code: SCI141

Recent studies have remarkably discovered that, in certain nonlinear systems, chaos can co-exist side-by-side with pure order. Such states were originally identified in the context of coupled nonlinear oscillators, where the chaotic (ordered) states correspond to de-synchronized (synchronized) regions. In analogy with the monstrous fire-breathing hybrid creatures of Greek mythology, these nonlinear states have been named chimera states.

Since their first discovery, chimera states have attracted significant attention. However, the vast majority of studies have been purely theoretical, with the number of experiments comparatively scarce. We have recently developed a novel experimental configuration based on nonlinear optical resonators, and made the first observations of chimera-like states in such systems.

The aim of this project is to provide theoretical support to our experimental project. Specifically, the goal of the project is to use numerical modelling to elucidate the dynamics and physics of nonlinear optical chimera states, and also to explore the system’s analogies with other systems where chimera states are known to manifest themselves.

The ideal candidate will have basic knowledge of either Matlab or Python. Good grasp of partial differential equations and bifurcation analyses is considered an additional plus.

Ultra-broadband model for microresonator frequency combs

Supervisor

Dr Miro Erkintalo

Discipline

Physics

Project code: SCI142

Optical frequency combs are light sources whose spectrum is composed of equally spaced narrow lines – each an ultra-stable laser in its own right. They were first developed in 2000, with the Nobel prize following five years later.

The first generation of frequency combs relied on bulky and expensive ultra-short pulsed mode-locked lasers. Remarkably, recent studies have shown that when a low-power monochromatic laser beam is launched into a microscopic nonlinear optical resonator, the input beam can spontaneously transform into hundreds or thousands of new frequency components, i.e., an optical frequency comb. The resulting microresonator frequency combs have attracted tremendous attention over the past few years, and today represent one of the hottest topics in contemporary photonics.

Our research group has developed numerical models that are today used around the world to simulate the generation of frequency combs in optical microresonators. However, the models in use neglect salient effects, which make them appropriate only for combs with narrow spectral width. With the performance of the comb generators rapidly increasing, there is a need for more complete models to simulate the resulting devices.

The purpose of this project is to expand the existing numerical models so that they are able to cope with ultra-broadband nonlinear frequency conversion in optical microresonators. This will in particular involve casting the models into frequency domain, where effects that are explicitly frequency-dependent can be modelled.

The ideal candidate will have experience with Matlab or Python, and a good grasp of partial differential equations and Fourier analysis.

Impact of de-synchronization on ultra-short pulses in passive Kerr resonators

Supervisor

Dr Miro Erkintalo

Discipline

Physics

Project code: SCI143

Temporal cavity solitons (CSs) are pulses of light that can go around and around a driven nonlinear resonator. While first observed in macroscopic optical fibre ring resonators, they have more recently attracted attention in the context of nonlinear microresonators, where they underpin the formation of so-called coherent optical frequency combs.

Most CS experiments involve driving a Kerr nonlinear resonator with a monochromatic laser beam. However, to improve the pump-to-CS conversion efficiency, researchers have recently begun to investigate the use of a short pulse to drive the resonator. We have recently performed numerical simulations that suggest de-synchronization between the driving pulse train and the resonator to dramatically impact the CS behaviours in such configurations.

In this project, you will experimentally investigate the impact of de-synchronization on the CS stability and existence, and compare your findings with predictions derived from numerical simulations.

The ideal candidate will have some background or interest in experimental physics and/or high-frequency electronics.

Fluid Motions in the “World’s Smallest Reactor”

Supervisor

Nicholas Demarais
Geoff Willmott

Discipline

Physics; Chemical Sciences; Chemical and Materials Engineering

Project code: SCI144

Electrospray ionization (ESI) can be used to generate femtolitre sized reaction chambers, known as “the world’s small reaction chambers”. This type of reactor is advantageous for monitoring reactions with expensive reagents or samples of limited quantity. While the fluid motions in ESI for a single, circular flow have been developed, the dynamics of a dual-flow system, made-up of two semi-circles, remains uncharacterized. This project will design, develop, and characterize the fluid motions in a dual-electrospray reactor. These results can be used to study chemical reactions, protein folding, or synthesize novel materials.

Key skills

  • Ability to work independently, think creatively, and manage complex tasks.
  • Experience with fluid mechanics and/or mass spectrometry would be useful, but is not necessary.
  • Someone that is good with their hands and enjoys building and designing will be well suited for this research.

Nanohardness of Sticky Surfaces

Supervisor

Dr Thomas Loho
Dr Steve Wells
Dr Miguel Balzan

Discipline

Physics; Chemical and Materials Engineering

Project code: SCI145

The hardness of surfaces can be tested on the nano-scale using a specialised indentor. The same nanoindentor can be used to test adhesion of tiny particles to surfaces by scratching them off.

We will apply this technique to baked-on layers of milk on steel surfaces, which can form “milkstone”.

Small droplets of milk will be hardened onto the milkstone in a high-temp chamber, then we will test their adhesion. Milkstone forms on steel surfaces during production of dairy powder products, and is notoriously difficult to remove. This project is aimed at developing better methods of removing milk deposits as they form.

Skills you will learn

  • High-precision measurements
  • Nano-scale material characterisation
  • Research for the real world (NZ industry)

Optical frequency combs in ultra-high Q microresonators

Supervisor

Stuart Murdoch

Discipline

Physics

Project code: SCI146

An optical frequency comb is an ultra-precise spectroscopic ruler that allows the measurement of optical frequencies with unprecedented levels of accuracy. These combs are now used in a myriad of applications ranging from extra-solar planet detection to optical telecommunications. Their discovery was awarded a Nobel prize in 2005. Optical microresonators are tiny optical cavities that can trap light for extended periods of time allowing for highly efficient nonlinear interactions. New research has shown that under the correct conditions optical microresonators can produce high-quality frequency combs. This opens up the possibility of new chip-scale comb devices.

The Auckland group has considerable experience in both the theory and experimental investigation of microresonator frequency combs. The successful candidate will work with our group on topics based around the theory, fabrication, and experimental implementation of new microresonator based comb designs.

Widely tunable microresonator parametric oscillators

Supervisor

Stuart Murdoch

Discipline

Physics

Project code: SCI147

Optical microresonators are tiny optical cavities that can trap light for extended periods of time allowing for highly efficient nonlinear interactions. Recent work, by our group, has shown that under the right conditions these devices can efficiently generate light at new wavelengths far from the original pump frequency. So far we have been able to demonstrate over an octave of narrowband tunability in these devices, with the output light tunable in wavelength from 1095 to 2539 nm. We now wish to push the performance of these devices even further and generate signals in the spectroscopically important ‘molecular fingerprint’ region around 3 um. The successful candidate will work with our group on the experimental and theoretical realisation of these exciting new devices.

Nonlinear polarization effects in optical fibre resonators

Supervisor

Stephane Coen

Discipline

Physics

Project code: SCI148

Nonlinear resonators driven with intense laser light exhibit a range of very useful properties. They also constitute a testbed for more general physics, including understanding of self-organization. For this project, we will consider optical fibre resonators driven with two different polarization components. This makes the behaviour of the system even more intricate. With such a platform, we can use light to study phenomena similar to the domain walls found in ferromagnetic materials. It also opens up a path to study solid-state physics effects that cannot be studied otherwise. The project will be based on an existing experimental setup, but can also involves numerical modelling, depending on interest.