We report on the first successful fabrication of functional optoelectronic devices using fiber drawing techniques. The metal-insulator-semiconductor optical fibers have led to the creation oftwo prototype fiber structures: A fiber photodetector, and a dual electron-photon transport fiber.To date, a barrier has existed between the fabrication technologies used for producing electronic devices and those used for optical fibers [1,2]. The former comprise a collection of elaborate wafer-based processes, while the latter rely on simpler preform thermal-drawing techniques. In a recent publication, we report on the first successful fabrication of functional optoelectronic devices using fiber-drawing techniques [3]. These fibers are made by arranging a low-melting temperature conductor (Sn), amorphous semiconductor (As2Se3 or AstoSesoTe1oSn5) [4], and a high-glass transition thermoplastic insulator [5] (polyethersulfone, PES, or polyetherimide, PEI) into a macroscopic prefcrm which shares the final fiber geometry, but lacks functionality due to the absence of intimate contact and proper element dimensions. This new technique has led to the creation of two prototypical functional fibers: I) a fiber photodetector, and (2) a fiber designed for dual electron-photon transport. Fig. 1. Fiber photodetectors. (a) A macroscopic preform consisting of a photoconductivc core made of a chalcogenide glass (As-Se-Te-Sn), surrounded by a polymer (PES) cladding. The core is contacted by four metal (Sn) electrodes that run along the length of the preform. (b) An SEM micrograph of the fiber cross section demonstrating that the preform geometly has been preserved during the drawing process. The photodetector fiber preform (33-mmn thick, Fig. la) consists of a cylindrical semiconductor chalcogenide glass (As40Se5oTejoSns) core, contacted by four Sn metal conduits that are encapsulated in a protective PES cladding, and is subsequently heated and drawn into a fiber (980-pm thick, Fig. lb). The fiber exhibits both electrical and optical functionalities that follow from the excellent contact, appropriate element dimensions, and the preservation of the preform geometry throughout the drawing process. Specifically, the electrical conductance of this fiber was found to increase dramatically (two orders of magnitude) upon illumination by white light (20 mW), as seen in the large slope of the linear I-V curve when compared to that recorded in dark conditions (Fig. 2a).While the individual fiber behaves as a distributed photodetector, with sensitivity to visible and infrared light at every point along its entire length, it is the assembly of such fibers into 2D grids or photodetectorfiber webs that enables the detection of an illumination point. Moreover this grid achieves N2 detection resolution with only a 2N number of elements. An example of such a fiber veb detector, that is used to measure the coordinates of an illumnination point on a 30x30 CM2 grid with 64-point resolution, is shown in Fig. 2b. 1686
