III-V compound semiconductor nanowires (NWs) have drawn much attention as nanoscale building blocks for integrated photonics/optoelectronics due to their nanoscale size, excellent optical properties and effectiveness in strain relaxation enabling the monolithic growth on lattice-mismatched substrates. In particular, NWs grown by selective area epitaxy technique have many advantages such as controllability of their size and position, high uniformity in diameter and length, as well as complementary metal-oxide-semiconductor (CMOS) process compatibility, facilitating their integration with other electronic devices. With suitable wavelength ranging from 1.3 to 1.6 μm and lattice match of constituent materials, InGaAs/InP quantum well (QW) has been being widely used for optical communication devices. However there has been limited understanding on the growth of InGaAs/InP QW in nanowire architecture and their application for optoelectronic devices such as lasers/LEDs and photodetectors. In this work, we present the study of the selective area epitaxy growth of InGaAs/InP multi-QW NW array by metalorganic chemical vapour deposition (MOCVD) technique, and the demonstration of nanowire LEDs/lasers and photodetectors with an investigation of their strong geometry related device properties by both numerical simulation and optoelectronic characterizations.

In this talk we plan to discuss a novel class of nanoscale devices that address unmet performance demands for applications in data communications. The performance of emerging generations of high-speed, integrated electronic circuits is increasingly dictated by interconnect density and latency as well as by power consumption. To alleviate these limitations, data communications using photons has been deployed, where photonic circuits and devices are integrated on platforms compatible with conventional electronic technologies. Within the dominant platform; namely Si, dielectric waveguides confine light via total internal reflection. This imposes bounds on minimizing device dimensions and density of integration. Those bounds arise due to the diffraction limit and the cross-coupling between neighboring waveguides. Nanoscale Plasmonic waveguides provide the unique ability to confine light within a few 10s of nanometers and allow for near perfect transmission through sharp bends as well as efficient light distribution between orthogonally intersecting junctions. With these structures as a building block, new levels of optoelectronic integration and performance metrics for athermal transceivers with achievable bandwidths of 100s Gbps and detection sensitivity better than -55 dBs, will be overviewed in this talk. In addition, opportunities for the role that 2D materials may pay in propelling these record performance metrics even further will be projected.

Nanophotonics modelling for 21St century applications is becoming vital.  The computational modeling provides a fundamental understanding of the relying physics behind the operation of photonic devices. However, computational modeling is still a challenge as some of the existing modeling techniques fail to capture the correct behavior of nano-photonic devices. In this regard, this talk will introduce an overview of the existing computational modeling tools for analyzing photonic  devices, in general, and highlighting their salient features and shortcomings. It is well known that “plasmonics” plays a vital role now in localising the optical field beyond the diffraction limit and hence in integrated optics. Therefore, the talk will focus on plasmonics modeling issues and the failure of the classical electromagnetic solvers to accurately characterize the nano-plasmonic devices. Therefore, new accurate and stable beam propagation method will be introduced for analyzing plasmonics in the classical regime. The rigor of this approach is mainly because of relying on the finite elements method and  the twice faster Blocked Schur algorithm which can exactly represent all the wide spectrum of radiation, evanescent, and surface modes produced by the strong discontinuity between metal and its surroundings. Moreover, in merging quantum plasmonic devices, it becomes essential to introduce “Quantum Corrected Model (QCM)” in order to accurately model these devices, and the basics of QCM will be also discussed.

About a quarter of the electricity generated worldwide is used for lighting.  Energy efficient light bulbs based on light emitting diodes (LEDs) are about five times more efficient than traditional incandescent bulbs, and hence have the potential to allow enormous energy savings.  The key material used in LEDs which emit white light is gallium nitride, a human-made compound, which has never been observed to occur in nature.  Optimising this new material to make LEDs which are efficient, long-lived and reasonably affordable has been a huge challenge, and despite the undoubted commercial success of these devices many aspects of their operation remain mysterious.  This lecture will explain how we can take LEDs apart, literally atom by atom, to understand their structure and how this controls their properties.  The relevant techniques emerged from traditional metallurgy, but are now being used to understand materials for cutting edge optoelectronic devices, illustrating how the basic principles of materials science are vital to the development of the technologies of tomorrow.

Porous semiconducting nitrides are effectively a new class of semiconducting material, with properties distinct from the monolithic nitride layers from which devices from light emitting diodes (LEDs) to high electron mobility transistors are increasingly made. The introduction of porosity provides new opportunities to engineer a range of properties including refractive index, thermal and electrical conductivity, stiffness and piezoelectricity. Quantum structures may be created within porous architectures and novel composites may be created via the infiltration of other materials into porous nitride frameworks.    A key example of the application of porous nitrides in photonics is the fabrication of high reflectivity distributed Bragg reflectors (DBRs) from alternating layers of porous and non-porous GaN.  These reflectors are fabricated from epitaxial structures consisting of alternating doped and undoped layers, in which only the conductive, doped layers are electrochemically etched. Conventionally, trenches are formed using a dry-etching process, penetrating through the multilayer, and the electrochemical etch then proceeds laterally from the trench sidewalls.  The need for these trenches then limits the device designs and manufacturing processes within which the resulting reflectors can be used. We have developed a novel alternative etching process, which removes the requirement for the dry-etched trenches, with etching proceeding vertically from the top surface through channels formed at naturally-occurring defects in the crystal structure of GaN. This etch process leaves an undoped top surface layer almost unaltered and suitable for further epitaxy. This new defect-based etching process provides great flexibility for the creation of a variety of sub-surface porous architectures on top of which a range of devices may be grown.  Whilst DBR structures enable improved light extraction from LEDs and the formation of resonant cavities for lasers and single photon sources, recent development also suggest that thick, subs-surface porous layers may enable strain relaxation to help improve the efficiency of red microLEDs for augmented reality displays.  Meanwhile, the option of filling pores in nitride layers with other materials provides new opportunities for the integration of nitrides with emerging photonic materials, such as the hybrid-perovskite semiconductors, with perovskites encapsulated in porous nitride layers demonstrating greatly improved robustness against environmental degradation.

A quantum light source is a device that can generate one single photon – or an entangled pair of photons - on demand.  Whilst a single photon emitter would be pretty useless as a car headlight or bedside lamp, these devices are in increasing demand for new developments in optical communication which might exploit fundamental principles of quantum physics to achieve data security.  Linear optical quantum computation, precision optical measurement and even random number generation also present potential applications opportunities for such light sources.   However, many of the most mature quantum light sources operate at temperatures only accessible using liquid helium, at best inconvenient and at worst prohibitive for applications.  Exploiting nitride semiconductors allows device concepts developed in the more conventional arsenide semiconductor family to be applied, but whilst arsenide devices are limited to cryogenic temperatures, nitride devices can operate at temperatures accessible using on-chip, Peltier cooling, and in some cases even at room temperature.    Unfortunately, working with these less mature semiconductors has its pitfalls: high densities of defects and the impact of internal electric fields can limit device performance.  For example, the wavelength of emission from nitride single photon emitters wanders with time, which is not compatible with applications which demand resonance of the emitter with a cavity or (more stringently) the emission of indistinguishable photons. Nitrides crystals grown in unusual orientations can overcome these challenges whilst maintaining good temperature stability, providing new opportunities for real-world quantum technologies.

Infrared detectors and imaging systems are becoming increasingly important in a diverse range of astronomic, military, and civilian applications. In recent years, this field has gained significant attention while incorporating various material combinations and architectures into detector designs with a strong focus on applicability into clinical domains. Here, we will discuss some of our detector structures, their results, and our latest work on disease detection. Our study of the biomedical application of infrared includes exploration of an Affordable, Sensitive, Specific, User-friendly, Rapid, Equipment-free, and Deliverable (ASSURED) diagnostic regimen and testing its clinical feasibility for inflammatory bowel diseases (IBDs) and cancer (Breast, Melanoma, and Lymphoma) screening. Our study using Fourier transform infrared (FTIR) spectroscopy in attenuated total reflectance (ATR) sampling mode, analyzed  body fluids in order to identify reproducible,  stable,  and statistically significant differences  in spectral signatures of the IR absorbance spectra between the control and disease samples. These results show that serum samples can be used to detect the biochemical changes induced by these diseases. This technology can be further developed into a futuristic, noninvasive, personalized diagnostic tool for various diseases in which patient-to-patient differences in molecular signatures would allow the assessment of disease status and personalized drug management.

In this lecture, I will try to convey a feeling for our course on “Survival Skills for Scientists”. This is a graduate course designed and developed in my department, in which we give basic advice and offer mentorship to our graduate students and post-docs. The central theme of this presentation is that succeeding in Science requires skills (often referred to as ‘soft professional skills’) beyond those needed for Science. The lecture aims at giving basic guidance and mentoring to young scientists (typically science and engineering undergraduate and first year graduate students. The main topics are: The job market for graduates in science and engineering (industry, national labs and academia; advantages and disadvantages) Funding in modern science Publish or perish; publishing quality papers, having an impact Presenting your work to your peers The fundamental laws of 'scientific survival' (know yourself, plan ahead, and play chess) Ethics in modern science Alternative careers

This presentation focuses on structure property/relationships in advanced materials, emphasizing multifunctional systems that exhibit multiple functionalities. Such systems are then used as building blocks for the fabrication of various emerging technologies. In particular, nanostructured materials synthesized via the bottom–up approach present an opportunity for future generation low cost manufacturing of devices. We focus in particular on recent developments in solar technologies that aim to address the energy challenge, including third generation photovoltaics, solar hydrogen production, luminescent solar concentrators and other optoelectronic devices.

As the age of cheap oil and fossil fuels is coming to an end, humanity will face an energy crisis. Many alternative energy sources have already been identified. However, there is no optimal solution to replace fossil fuels on a short time scale with new sources that are economically viable and environmentally sustainable in the long term. History reports disastrous consequences for human societies that exploited their resources in a non sustainable way, and arguably this is exactly what is happening today on a global scale. Evidence for climate change is overwhelming. This public lecture aims at describing a general picture of the looming energy crisis, particularly to promote awareness. Some possible solutions are discussed, involving the use of advanced materials and nanotechnology for energy saving, energy storage and energy conversion.