Exploiting Collective Effects of Multiple Optoelectronic Devices Integrated in a Single Fiber Fabien Sorin, †,‡,§ Ofer Shapira, ‡,§ Ayman F. Abouraddy, | Matthew Spencer, ⊥ Nicholas D. Orf, †,‡,§ John D. Joannopoulos, §,# and Yoel Fink* ,†,‡,§ Department of Materials Science and Engineering, Research Laboratory of Electronics, Institute for Soldier Nanotechnology, Department of EECS, Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and CREOL, The College of Optics and Photonics, UniVersity of Central Florida, Orlando, Florida 32816 Received March 26, 2009; Revised Manuscript Received May 29, 2009 ABSTRACT The opportunities and challenges of realizing sophisticated functionality by assembling many nanoscale devices, while covering large areas, remain for the most part unrealized and unresolved. In this work, we demonstrate the successful fabrication of an eight-device cascaded optoelectronic fiber structure in which components down to 100 nm are individually electrically addressed and can operate collectively to deliver novel functionality over large area coverage. We show that a tandem arrangement of subwavelength photodetecting devices integrated in a single fiber enables the extraction of information on the direction, wavelength, and potentially even color of incident radiation over a wide spectral range in the visible regime. Finally, we fabricated a 0.1 square meter single plane fiber assembly which uses polychromatic illumination to extract images without the use of a lens, representing an important step toward ambient light imaging fabrics. The fabrication of multimaterial fibers involves the construc- tion of macroscale preforms that are subsequently stretched into long (hundreds of meters), thin, flexible, and lightweight fibers that deliver prescribed functionalities. 1 Optical trans- port, 2,3 external reflection, 4 lasing, 5 but also optical 6-8 and thermal 9 detection can be achieved in fibers integrating a judicious choice of materials, engineered in a proper structure. This renders these fibers systems a compelling candidate for applications such as remote and distributed sensing, large-area optical-detection arrays, and functional fabrics. 1,6-9 A limitation of these novel fiber devices, however, has been the challenge of integrating multiple optoelectronic components into a single fiber cross-section. This is in fact a common problem in nanotechnology where the drive toward smaller and smaller nanoscale devices complicates the ability to integrate and individually address many of them, especially over very large-area coverage. Integration of multiple devices to work collectively is however key to the delivery of complex functionality. The fabrication process described here demonstrates that this limitation can be overcome in polymer fibers. We show that ordered, independent, and globally oriented nanometer scale devices of unprecedented aspect ratio can be integrated within lightweight and flexible fiber substrates that can potentially cover and functionalize very large surface areas (several square meters) and fabric systems. The fiber integrated devices presented here consist of a pair of metallic electrodes contacting a semiconducting ring that extends along the entire fiber axis, as depicted in Figure 1. Several such pairs can be placed along the ring circumfer- ence, and multiple successive rings can be cascaded in the radial direction, forming an integrated system of increasing device density. Schematic diagrams in Figure 1a depict the different steps we developed to produce a preform of two embedded semiconductor rings, each contacted by four electrodes. A series of polymer tubes having precise dimen- sions so that they fit tightly into each other are fabricated. Thin layers of semiconducting film of prescribed thickness are thermally deposited on a polymer substrate and rolled onto specific tubes. The set of tubes and semiconductor films are then stacked together to form the macroscopic preform. After thermal consolidation under vacuum, the preform is thermally drawn into a fiber that preserves the original cross- * To whom correspondence should be addressed. E-mail: yoel@mit.edu. † Department of Materials Science and Engineering, Massachusetts Institute of Technology. ‡ Research Laboratory of Electronics, Massachusetts Institute of Techno- logy. § Institute for Soldier Nanotechnology, Massachusetts Institute of Technology. | University of Central Florida. ⊥ Department of EECS, Massachusetts Institute of Technology. # Department of Physics, Massachusetts Institute of Technology. NANO LETTERS 2009 Vol. 9, No. 7 2630-2635 10.1021/nl9009606 CCC: $40.75  2009 American Chemical Society Published on Web 06/15/2009 Downloaded by UNIV OF CENTRAL FLORIDA on July 13, 2009 Published on June 15, 2009 on http://pubs.acs.org | doi: 10.1021/nl9009606