Tapered Semiconductor Fibres

Semiconductor photonics is a field that is currently revolutionizing the future of modern optoelectronic devices. Although semiconductor materials are more commonly associated with electronic functionality (e.g., popular gadgets that use semiconductor microelectronic processors include cell phones, computers, and digital radios), to date a number of important photonic devices have been demonstrated using planar based substrates on a chip including silicon lasers and germanium photodetectors. More recently, however, the incorporation of semiconductor materials into the core of optical fibres has generated much interest as it provides a unique opportunity to completely integrate this technology with existing silica fibre infrastructures used in data transmission networks. Fiberized semiconductor devices offer some notable advantages over those developed on-chip such as simple, low cost fabrication (i.e., no need for multimillion dollar cleanroom based lithography) and robust and versatile waveguide geometries. Furthermore, the wide (visible to far-infrared) optical transparency of the semiconductor materials that can be incorporated into the fibre geometry ensures that their applications will extend far beyond optical communications to disciplines such as medicine, sensing, spectroscopy and security monitoring. The work described in this proposal seeks to combine this exciting new semiconductor fibre platform with a key waveguide technology: tapered optical fibres. Conventional tapered silica fibres, which have varying waveguide dimensions along the length, have been exploited for a wealth of applications such as, optical signal processing, supercontinuum generation, remote sensing, as well as for optimized mode coupling between devices. The extension of these structures to incorporate semiconductor materials with rich optoelectronic functionality into the tapered cores will present new degrees of design flexibility for the optimization of semiconductor optical waveguides. The primary goal of this work will thus be to develop the procedures for the fabrication of high quality tapered semiconductor fibre structures and to demonstrate their potential for nonlinear photonic applications. This highly innovative project has the potential to lead to the development of a number of technologically disruptive all-fibre optoelectronic devices, for example, ultra-compact broadband mid-infrared laser sources for healthcare, frequency combs for chemical analysis, and highly nonlinear optical couplers and switches for ultrafast telecommunications.