Doctoral Candidates

Developing metasurfaces to convert far-field illumination into a well-designed near-field so that the chiroptical response of chiral matter can be enhanced and the sensitivity of optical chiral sensing can be improved.

The main goal of the project is to enhance single photon detection efficiency of superconducting nanowire single-photon detectors (SNSPD) in the range of 800-1500 nm by frequency-selective metasurfaces. 

My initial goal is to integrate TMD monolayers on other photonic structures to enable different types of dark excitons to be directly addressable by normal incident light. I am taking two different approaches to this. First, I am working with all-dielectric metasurfaces. Their in-plane modes can be coupled by weak leakage via quasi-BICs (Bound states In the Continuum) to spin-forbidden dark excitons in TMD monolayers, which in turn leads to detectable far-field emission. Second, I plan to integrate TMD monolayers on metallic chirped gratings, which will allow direct access to momentum-forbidden dark excitons by introducing additional momentum provided by the photonic structure. Furthermore, I will work on the resonant light emission enhancement of dark excitons in 2D materials by exploiting their crystal symmetry and valley selection rules to pave the way for future integrated solutions for quantum optics and valleytronics.

Metasurfaces have shown great potential in various fields, including chemical and biological sensing. By integrating metasurfaces with III-V semiconductor nanowire LEDs, it is possible to create integrated sensing systems with enhanced functionality and performance.

As artificial photosynthesis, the photocatalytic reduction of CO2 addresses the emission of greenhouse gases by converting them back to organic fuels with solar energy. These redox reactions include multiple electron transfer processes and various products were generated vas separated reaction pathways simultaneously, such as formic acid, formaldehyde, methanol, methane, and some higher hydrocarbons products. Therefore, it is challenging to have a highly efficient, stable conversion of a single product. Metasurfaces with a plasmonic materials promote the concentration of hot electrons on the surface and optical near-field enhancement which have a great potential in photocatalysis. 

My research focuses on utilizing metasurfaces, specifically resonant dielectric metasurfaces composed of tailored non-inversion symmetric effective nonlinear media, to achieve efficient second-order nonlinear processes like second harmonic generation and sum-frequency generation. By constructing dielectric metasurfaces from engineered nanocomposites consisting of tailored dielectric-based nanolaminates grown through advanced deposition techniques, we can enhance the nonlinear optical properties and introduce tailored symmetry breaks in the meta-atoms' composite materials. This approach allows for the optimization of the nonlinear response and the manipulation of the far-field properties of the generated fields. The long-term vision is to expand the range of materials used for layer growth, including metals deposited by atomic layer deposition (ALD) to broaden the capabilities and applications of metasurfaces in nonlinear optics.

My thesis focuses on the development of a metasurface-based quantum imaging technique, which incorporates a novel quantum light source from a nonlocal metasurface. Traditionally, entangled photon pairs are generated from bulky crystals through Spontaneous Parametric Down Conversion (SPDC) due to their high nonlinear susceptibility. However, the utilization of a designed nonlocal metasurface with resonance frequency can overcome the challenges that exist with bulky crystals such as low generation rate, temperature control, and manipulation. The PhD thesis comprises several crucial phases. In the first year, we aim to demonstrate the feasibility of developing a quantum imaging system with a metasurface-based quantum light source. Subsequently, we will focus on phase imaging and edge sensing using this system. Furthermore, we plan to optimize the system by changing the metasurface material and design for non-degenerate light source and enhancing imaging. Ultimately, our objective is to establish a multifunctional quantum imaging system.

The goal of this project is to develop a new family of tunable atomically thin flat lenses. Two-dimensional TMDs (Transitional Metal Dichalcogenides) show direct bandgap in their monolayer form along with excitonic behavior. My work is to utilize excitonic resonances in order to realize ultrafast all-optical tunable metalenses based on ground state bleaching and ultrafast all-optical tuning of the nonlinearities in TMDs. These ultrafast all-optically tunable thin flat lenses have potential application in 3D displays, augmented reality, virtual reality and future photonic integrated circuits.

The goal of the project is to enhance the emission properties of nanoscopic emitters by tailoring their local environment.  

This project aims to generate polarization entangled photon pairs from metasurfaces using spontaneous parametric down-conversion (SPDC). 

The aim of my project is to demonstrate the effectiveness of upconversion IR imaging using high-Q bound-state-in-the-continuum resonances found in nonlinear optical metasurfaces. 

Luyao is immersed in the fascinating field of tunable metasurfaces. Driven by a steadfast quest for faster tuning methods, her research endeavors to uncover new possibilities in this exciting field of electro-optics metasurfaces. 

My project is dedicated to the investigation and tailoring of the light-emission processes such as spontaneous or stimulated emission of the quantum emitters and their far-field emission pattern properties, using all-dielectric metasurfaces incorporating or hybridized with polymer layers containing laser dyes or fluorescent molecules. 

I am working on liquid-crystal tunable metasurfaces. My focus is on achieving spatially variant active control of the metasurface optical properties. To this end I use structured light as a stimulus to alter the properties of the metasurface system as a function of in-plane position.

The project focuses on using plasmonic materials to enhance the efficiency of photocatalytic reactions that convert carbon dioxide (CO2) into carbon-based fuels or value-added chemicals.These plasmonic materials can interact with light at a very small scale and concentrate the electromagnetic field around them, known as surface plasmon resonance. By optimizing the composition, size, and shape of plasmonic nanoparticles, the aim is to selectively convert CO2 into desirable products while minimizing unwanted by-products. This involves designing photocatalyst materials with specific active sites to promote the adsorption and activation of CO2 molecules, facilitating their conversion selectively.

The investigation aims to advance our understanding of plasmonic-driven photocatalysis for selective CO2 reduction, which can contribute to sustainable and efficient strategies for reducing carbon dioxide emissions and utilizing CO2 as a valuable resource. The findings have important implications for designing future photocatalytic systems that can play a significant role in addressing climate change and promoting a transition to a carbon-neutral society.

This project is focussed on the design, fabrication and characterisation of actively tunable devices for the spatiotemporal control of light fields, with specific regard to optical beam steering. In this case the metasurface deflects an incident reflected or transmitted field in a programmable way that allows for scanning over a particular field of view. Optical beam steering has many applications including optical communications, LIDAR and laser machining.  Current devices are based on mature technologies that have limited potential for further SWaP-C (size, weight, power, and cost) improvements. Metasurface beam steering is well placed to overcome many of their shortcomings.

I focus on the design of metasurfaces. The goal of the project is to achieve a vast variety of application through intelligent design of metasurface.

The PhD is to develep inverse design algorithms that can be used to design metasurfaces for tailored applications; these include polarisation control, beam deflection, non-linear generation and phase discrimination. 

Enhancing and controlling the nonlinear effects by geometrically optimized metasurfaces to broaden the application prospects of metasurfaces in wavefront control and photon pair generation.