Metal–insulator–semiconductor optoelectronic fibres

Abstract

The combination of conductors, semiconductors and insulators with well-defined geometries and at prescribed length scales, while forming intimate interfaces, is essential in most functional electronic and optoelectronic devices. These are typically produced using a variety of elaborate wafer-based processes, which allow for small features, but are restricted to planar geometries and limited coverage area. In contrast, the technique of fibre drawing from a preformed reel or tube is simpler and yields extended lengths of highly uniform fibres with well-controlled geometries and good optical transport characteristics. So far, this technique has been restricted to particular materials and larger features. Here we report on the design, fabrication and characterization of fibres made of conducting, semiconducting and insulating materials in intimate contact and in a variety of geometries. We demonstrate that this approach can be used to construct a tunable fibre photodetector comprising an amorphous semiconductor core contacted by metallic microwires, and surrounded by a cylindrical-shell resonant optical cavity. Such a fibre is sensitive to illumination along its entire length (tens of meters), thus forming a photodetecting element of dimensionality one. We also construct a grid of such fibres that can identify the location of an illumination point. The advantage of this type of photodetector array is that it needs a number of elements of only order N, in contrast to the conventional order N2 for detector arrays made of photodetecting elements of dimensionality zero.

Thermal‐Sensing Fiber Devices by Multimaterial Codrawing

“…Specifically, both thermal and electrical functionalities are obtained in the fibers studied in this communication, while optical and optoelectronic functionalities in alternative designs have been obtained previously and are reported elsewhere. [6,7] The fibers are produced by a novel fabrication technique that enables the incorporation of materials with widely disparate electrical and thermal properties in a single, macroscopic, cylindrical preform rod, which subsequently undergoes thermal drawing to give solid-state microstructured fibers with high uniformity. The main requirements in the materials used in this preform-to-fiber approach are as follows: 1) the component which supports the draw stress should be glassy, so as to be drawn at reasonable speeds in a furnace, with self-maintaining structural regularity; 2) the materials must be above their respective softening or melting points at the draw temerature to enable fiber codrawing; and 3) the materials should exhibit good adhesion/wetting in the viscous and solid states without delamination, even when subjected to thermal quenching.…”

Optimized design of a low-resistance electrical conductor for the multimegahertz range

“…At such frequencies, resistance is dominated by skin-depth effects, which prevent the current from being uniformly distributed over the cross section; this is typically combatted by breaking the wire into a braid of many thin insulated wires (litz wire 1 ), but the ∼ 10 µm skin depth at these frequencies makes traditional litz wire impractical (∼ 10 4 µm-scale strands). In contrast, we show that as few as 10 coaxial shells can improve resistance by more than a factor of 3 compared to solid wire, and thin concentric shells can be fabricated by a variety of processes (such as electroplating, electrodeposition, or even a fiber-drawing process [2][3][4]. Good conductors at these frequencies are increasingly important, e.g.…”

Surface Textured Polymer Fibers for Microfluidics

“…[29][30][31][32] This simple and robust manufacturing process enables to maintain well defi ned material geometries along the length of the fi ber. In this work, we utilized fi ber drawing method to modify fi ber surface morphology in order to obtain enhanced anisotropic wetting on fi ber surfaces.…”