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ELEC0109 Advanced Photonic Devices

Course Summary:

To provide an in-depth understanding of the design, operation and performance of advanced photonic devices including light emitting diodes, LEDs, a range of semiconductor lasers, photodetectors, liquid crystal devices, photovoltaic solar cells for a variety of applications including optical communications and solar power generation.

Intended Learning Outcomes

On completion of this course, students should be able to:

• Know and understand the scientific principles and methodology of light generation, detection, and modulation and to use this to understand the operation and evolution of advanced photonic devices so that they can appreciate historical, current, and future developments and technologies.
• Have a comprehensive understanding of the scientific principles of light generation, detection and modulation and to use this to understand the operation and evolution of advanced photonic devices and their use in telecommunications and in solar power generation;
• Know and understand the mathematical principles necessary to underpin their education in advanced photonic devices and apply mathematical methods, tools and notations proficiently in the analysis and solution of engineering problems.
• Be aware of developing technologies related to advanced photonic devices.
• Apply and integrate knowledge and understanding of other engineering disciplines to support study of their own engineering discipline.
• Know and understand mathematical and computer models relevant to the engineering discipline, and an appreciation of their limitations.
• Understand concepts from a range of areas including some outside engineering such as from physics and chemistry, and the ability to apply them effectively in engineering projects.
• Understand engineering principles and can apply them to analyse key engineering processes. · Use fundamental knowledge of device materials and device fabrication to investigate new and emerging technologies.
• Identify, classify, and describe the performance of systems and components using analytical methods and modelling techniques.
• Work with technical uncertainty.

Course Content:

Photonic materials and properties

Glass; Crystals; Rare Earth-doping; Semiconductors; Nanotechnology, Bulk; Quantum Wells, Nanowires, Quantum Dots; Liquid Crystal Photon absorption; Homo-structure; Hetero-structure; Spontaneous emission; Stimulated emission; Non-radiative decay; Energy bands; Band Offsets; Optical Gain; Lasing Condition; Labelling of Modes; Near Field; Far Field; Temperature Dependence; Density of states; Fermi level; Quasi-Fermi levels; Direct and Indirect Bandgaps States in the gap; impurities and defects; Carrier recombination; Non-Radiative recombination; Radiative recombination; Radiative efficiencies; Lifetimes; Electro-optic refractive index modulation: CIE, Plasma effect, QCSE; Non-linearities, Molecular Beam Epitaxy

LEDs, lasers, amplifiers and optical filters

Historical Development of Semiconductor Lasers; Gratings; Laser Structures; Fabrication techniques (Fibre and Semiconductors); Photonic Band gap structures, The rate equation model; Optical Confinement Factor; spectral linewidth; LEDs; Amplifiers; Lasers; Fabry Perot cavity; Ring cavity; Laser Noise, Frequency Chirping; Laser examples: VCSEL, DFB, DBR, External Cavity; Relaxation Resonance; Relaxation Oscillation; Turn-on Delay; Damping; Laser direct modulation; Laser Characteristics; Semiconductor laser fabrication (Waveguide, vertical cavity)

Photodetectors (optional)

Liquid Crystal Photonic Devices

Physical properties of liquid crystal materials in the context of phase and amplitude modulation of light; polarisation and phase modulation; diffractive elements; optical filters; application of diffraction and optical filters using liquid crystals; device structures; analysis of the performance in relation to various applications.

1. The main aims of the course and how it links to previous courses you may have studied

The course teaches fundamental physics as well as device design and system applications, so it is quite wide ranging and in that sense this course is difficult. In order to fully understand a device you need to think of it in multiple ways at the same time which is a second reason it is difficult: Physical 3D structure, material behaviour, energy levels of electrons and holes in the material, spectrum of generated light, time domain response, spatial distribution of light in 3D, modulation speed characteristics, the way the material affects the polarisation of light. This course teaches the fundamental physical principles of semiconductor materials and liquid crystal materials and the interaction of light with them, including light generation, modulation and detection. The course also teaches the principles of device design to make use of the physical behaviour of the materials to maximise their performance and efficiency as well as minimising any disadvantages or problems associated with the physical behaviour of the materials. Many of the devices are related to optical fibre communications. We explain how LEDs and Lasers work and can be designed. The course includes advanced mathematics including linear algebra, linear systems theory, convolution theory, 3D Fourier Transforms, rate equations and briefly makes use of coupled wave equations and perturbation theory. After studying this course, you will be able to understand and analyse research papers written for PhD students and other researchers and professors. You will be able to design your own optical devices for particular applications.Ìý

2. Where it is relevant? Does the course have clear links to particular industries or careers?

Past students who took this course are now deans and professors at universities around the world or lead development and research groups at major companies. Several of the professors in our department took this course when they were students and their research is now in the subject area of this course in which they have become world leading researchers as they became very excited by the topics being taught. Several students who took this course went on to design/invent new types of laser. This course has clear links to UK and international industries involved in semiconductor manufacturing and growth, photolithographic manufacturing of silicon chips, lens and mirror manufacturing, laser, optical modulator and photodiode manufacturing and in their use in optical fibre communication systems, connectors to couple lasers and optical fibres, laser scanning LIDAR hardware and software, precision metrology, displays, virtual reality goggles, 3D data processing, object recognition, hidden optical security features for banknotes, concert tickets and driving licences, nanostructured surfaces for self-cleaning windows, autonomous vehicle 3D vision systems, astronomical telescopes, design of buildings, endoscopes for viewing and destroying tumours. You can expect salaries in the range £40,000 to £100,000 in these industries depending on your degree grade and experience, where the upper end would be for those starting and running companies as CEO or running the technical development group as CTO.

3. Method of delivery for this year

All the lectures are provided in short video segments online on the module moodle web site. The work to be carried out is also specified on the moodle site together with directed reading, online books and past years assessments to study each week. The lectures should be watched, the directed reading completed, and past years assessments attempted before the in-person workshop tutorials. In-person weekly workshops/tutorials are held each week of study with the individual lecturers to help explain the teaching material. The style of workshop tutorial will vary from one lecturer to another and may include answering student’s questions on topics in that week’s lecture that they did not understand or explaining some of that material again in more detail, going through past years assessments to show the level of detail required in the answers, discussing their own research and projects. Students may present their own answers to past years assessments and received immediate and direct feedback. We will aim to run the workshop tutorials in a hybrid mode using Zoom or Teams for students who cannot travel to the workshop tutorial in time from their earlier lecture.

3. What is the form of assessment for this module?

The course is 100% assessed by means of one major piece of coursework. This is a novel form of assessment as the students are directed to several research papers which they must read and answer questions on, to show that they can understand and analyse them. In past years the research papers have been in top peer reviewed journals, or have just been published before the assessment is set or consist of power point slides presented by researchers at conferences or have been papers, we have published on our research. So the work being understood and analysed is state of the art. The material taught in the module builds the foundational knowledge, understanding and techniques enabling the students to understand the most recent published research.

4. Who will be teaching on the course and their (research) interests linked to the course

The lecturers and professors teaching the course are carrying out world leading research in the topics of the course and so are fascinated and excited by the interactions of light and materials and are very keen for you to join them in their research groups as PhD students if you also find this subject enthralling and are able to achieve high marks in this course. Our interests extend from fundamental physics to applied optical engineering in industry.

David R. Selviah is the module leader and has taught at ¹û¶³Ó°Ôº for over 30 years. For 10 years he designed electronic devices, fabricated them in clean rooms and tested them in industry and in universities. His current research is in applications of laser scanning LIDAR for making accurate models of 3D environments, precision location and tracking of mobile phones indoors. David founded the company, Correvate, with 15 employees, to exploit his inventions and patents in the field of 3D laser scanning. Correvate provides the first cloud-based 3D data processing and 3D object recognition service via their Vercator® platform. Vercator is used by robots and drones after laser scanning underground mines, railways and buildings under construction to build 3D models and to recognise and classify objects.

Siming Chen is a Royal Academy of Engineering Fellow and a Lecturer in the Department of Electronic & Electrical Engineering at ¹û¶³Ó°Ôº. His research interests include: Silicon photonics integration; Quantum dot technology; Semiconductor Lasers and optical amplifiers; Semiconductor mode-locked lasers. Dr Chen has published > 80 papers in internationally leading journals and conferences, first and/or corresponding authored over 40 of them with several high-profile journal papers, including Nature Photonics, Nature Communications, Optica and ACS Photonics etc.

Huiyun Liu was awarded Royal Society University Research Fellow, and started his academic career by taking Senior Lecturer at ¹û¶³Ó°Ôº with commissioning the first new Molecular Beam Epitaxy Facility in central London in 2007. He was promoted as Professor of Semiconductor Photonics in 2012. He has more than 20 years of experience on the nanometre-scale engineering of low-dimensional semiconductor structures, including quantum wells, quantum dots and nanowires by using Molecular Beam Epitaxy and the development of novel optoelectronic devices including lasers, detectors, solar cells, and modulators. He holds on several international patents on silicon photonics and epitaxial materials and co-authored more than 300 papers, including Nature Photonics, Nature Materials, Nature Communications, Science Advances, Nano Today, Nano Letters, Light Science & Applications, and Optica etc.

Sally Day joined ¹û¶³Ó°Ôº as a Royal Society University Research Fellow and has worked on the applications of liquid crystal in many different systems, a proportion of which are relevant to this course. She has 25 years of experience in the physics and engineering of liquid crystal devices, including leading on research projects at ¹û¶³Ó°Ôº in collaboration with many different industries, aiming to use the unique properties of liquid crystals to achieve modulation or tuning of optical properties of devices in various optical systems. These will be studied in the APD module.