The development of optical fibres led directly to the data communications revolution of the late 20th century and are now impacting many other fields from remote sensing to biomedicine. This impact is growing in part because of rapid advances in active devices for which the fibre serves not merely as a passive waveguide, but as a medium to directly modulate, generate, or otherwise manipulate light. As a result of this versatility, fibres form key components of systems in almost any applications that use light. In parallel with these breakthroughs in photonics, the computer and microelectronics industries has seen exponential growth every 18 months since the 1960's of the performance to price ratio of transistors on CPU and DRAM chips, with commensurate improvements in optoelectronic components such as the visible lasers used in DVD players, and the infrared laser diodes used to generate and modulate light for data communications in optical fibres. The crystalline semiconductors upon which all microelectronics is based, namely silicon, germanium, gallium arsenide and many others, are familiar to almost every scientist and engineer. The advanced technological fields represented by fibre optics that are based on very long, very thin strands of glass and microelectronics based on planar chips fabricated by lithography, are typically integrated to create communication network systems by using intermediate optics and packaging. However, the technology we are developing allows crystalline semiconductor structures made from silicon and germanium directly inside the optical fibre itself. This technique utilises a deposition process similar to that used for modern planar electronic devices and so opens up the possibility for directly combining the light guiding capabilities of optical fibres with the exceptional capabilities of semiconductors for manipulating light and electrons. This suggests that many of the functions currently performed by planar optoelectronics might now be integrated directly inside the fibre itself, and that many new semiconductor devices that cannot be realised in a conventional planar geometry may now become possible. Advanced technological applications demand high performance devices, which in turn require exceptional materials; our efforts focus on the fundamental materials research and development necessary to move this innovation beyond the laboratory to next generation photonic devices and systems.