Efficient Photonic Devices for Near- and Mid-Infrared Applications

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This project aims to address many issues of growing importance in today's world. We are all becoming increasingly technology-dependent, whether for entertainment, critical areas, e.g. healthcare and perhaps most notably for communication. All of these technologies require energy and as our appetite for higher performance, faster and better technology increases, the demand on natural resources increases correspondingly. Photonics (the use and manipulation of light) is perhaps one of the most widely used technologies, whether it be for sending information at high speeds across the internet, for reading/writing data onto DVDs, laser surgery and so on. Photonic components (lasers, light emitting diodes etc.) are the fundamental building blocks of this technology and are produced in their billions annually (with revenues in the multi $1Bs). In spite of the widespread use of these devices, their efficiency is often relatively low, and compounded by a strong temperature sensitivity, particularly for devices operating in the near- and mid-infrared regions of the electromagnetic spectrum. This has largely held back the widespread deployment of mid-infrared lasers, for example in environmental and medical sensing (many gases are absorbed at these wavelengths) and other forms of free-space optical communication. In the near-infrared, telecommunications lasers operating in the optical fibre optimum transmission window at 1.55um are both inefficient and temperature sensitive. As a result, these devices require additional control electronics which consume significantly more power than the lasers themselves! Typically, more than 90% of the energy is such a system is wasted as heat.This proposal aims to tackle these issues in a coordinated manner since the core issues influencing near- and mid-infrared emitters is the same. The approach of this project is two-fold: (a) to work to develop a better understanding of the physical processes which give rise to poor efficiencies and to work in collaboration with other leading international groups towards developing new semiconductor materials systems which the PI has predicted will strongly suppress such processes (e.g. narrow band gap quantum dot systems and relatively unexplored semiconductor alloys, such as (In)GaAsBi) and (b) to develop novel materials such as dilute nitride phosphides to embed photonic components directly in electronic circuits, which are primarily silicon based. Routing data optically in such circuits could significantly reduce power (heat) dissipation in computers. Together, these approaches offer the potential to provide both large energy savings due to the use of better materials, and cost savings in manufacture, due to integration.The materials and devices in this project will be obtained from leading semiconductor growth groups in North America, Europe and Asia. At Surrey, the PI has established unique experimental techniques (e.g. low temperature and high pressure systems) to probe the physical properties of photonic materials and devices and will use these to determine both the basic materials parameters and the influence these have on device performance. The fellowship will allow the PI an excellent opportunity to lead a significant effort working together with a strong international team to investigate the fundamental physical characteristics of new materials with the aim of developing high efficiency improved photonic technology for widespread applications of importance to UK industry.