Optical fibers and semiconductor devices differ significantly in their properties and their processing approaches. The latter require the assembly of metal, insulating, and semiconducting materials into complex geometries with small feature sizes (sub 100 nm), while maintaining high quality interfaces. Sophisticated logic and detection functions are realized through the integration of many such devices onto a chip. Conventional optical fibers have been restricted to insulating materials, much simpler cylindrical, symmetric structures, and larger feature sizes (order of a micrometer). Consequently, a single fiber operates as a single optical transport device. Indeed the notion of integration has been foreign to optical fibers. Their processing, however, is much simpler compared to semiconductor devices as it utilizes a macroscopic preform to microscopic fiber fabrication approach. This process can efficiently yield highly uniform, long, and flexible fibers amenable to the formation of large-area assemblies and woven fabrics. In this talk, I will establish that, in principle, sophisticated semiconductor devices can be produced using simple preform-to-fiber thermal drawing techniques. A new materials processing paradigm will be introduced where, for the first time, metals, insulators, and semiconductors are thermally co-drawn in intimate contact and prescribed geometries. This enables the fabrication of fiber devices and fiber assemblies with unprecedented optic, electronic, and optoelectronic functionalities. In particular, the concept of one-dimensional, distributed photodetecting fibers will be introduced, together with a theoretical and experimental demonstration of how higher device integration in a single fiber can significantly improve performance and functionality. A lens-less imaging system using a single grid made of these fibers with angular and spectral resolution will be presented. Also, the first field effect and logic function observed in a thermally drawn semiconductor metal insulator fiber will be reported, opening the way toward increasingly complex electronic devices produced at fiber optic scales, uniformity, and cost. Finally, I will present a few real-world application projects currently under development.


Seminar, November 17, 2008, 12:00h. Seminar Room

Hosted by Prof. Valerio Pruneri