77 research outputs found
Programming scale-free optics in disordered ferroelectrics
Using the history-dependence of a dipolar glass hosted in a
compositionally-disordered lithium-enriched potassium-tantalate-niobate
(KTN:Li) crystal, we demonstrate scale-free optical propagation at tunable
temperatures. The operating equilibration temperature is determined by previous
crystal spiralling in the temperature/cooling-rate phase-space
Self-assembled fibre optoelectronics with discrete translational symmetry
Fibres with electronic and photonic properties are essential building blocks for functional fabrics with system level attributes. The scalability of thermal fibre drawing approach offers access to large device quantities, while constraining the devices to be translational symmetric. Lifting this symmetry to create discrete devices in fibres will increase their utility. Here, we draw, from a macroscopic preform, fibres that have three parallel internal non-contacting continuous domains; a semiconducting glass between two conductors. We then heat the fibre and generate a capillary fluid instability, resulting in the selective transformation of the cylindrical semiconducting domain into discrete spheres while keeping the conductive domains unchanged. The cylindrical-to-spherical expansion bridges the continuous conducting domains to create ∼10⁴ self-assembled, electrically contacted and entirely packaged discrete spherical devices per metre of fibre. The photodetection and Mie resonance dependent response are measured by illuminating the fibre while connecting its ends to an electrical readout.National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (DMR-1419807)United States. Army Research Office. Institute for Soldier Nanotechnologies (contract number W911NF-13-D-0001)United States. Air Force Medical Servic
Electrostrictive microelectromechanical fibres and textiles
Microelectromechanical systems (MEMS) enable many modern-day technologies, including actuators, motion sensors, drug delivery systems, projection displays, etc. Currently, MEMS fabrication techniques are primarily based on silicon micromachining processes, resulting in rigid and low aspect ratio structures. In this study, we report on the discovery of MEMS functionality in fibres, thereby opening a path towards flexible, high-Aspect ratio, and textile MEMS. The method used for generating these MEMS fibres leverages a preform-To-fibre thermal drawing process, in which the MEMS architecture and materials are embedded into a preform and drawn into kilometers of microstructured multimaterial fibre devices. The fibre MEMS functionality is enabled by an electrostrictive P(VDF-TrFE-CFE) ferrorelaxor terpolymer layer running the entire length of the fibre. Several modes of operation are investigated, including thickness-mode actuation with over 8% strain at 25 MV m -1 , bending-mode actuation due to asymmetric positioning of the electrostrictive layer, and resonant fibre vibration modes tunable under AC-driving conditions.National Science Foundation (U.S.) (Award DMR-1419807)Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (Contract W911NF-13-D-0001
Silicon-in-silica spheres via axial thermal gradient in-fibre capillary instabilities
The ability to produce small scale, crystalline silicon spheres is of significant technological and scientific importance, yet scalable methods for doing so have remained elusive. Here we demonstrate a silicon nanosphere fabrication process based on an optical fibre drawing technique. A silica-cladded silicon-core fibre with diameters down to 340 nm is continuously fed into a flame defining an axial thermal gradient and the continuous formation of spheres whose size is controlled by the feed speed is demonstrated. In particular, spheres of diameter \u3c 500 nm smaller than those produced under isothermal heating conditions are shown and analysed. A fibre with dual cores, p-type and n-type silicon, is drawn and processed into spheres. Spatially coherent break-up leads to the joining of the spheres into a bispherical silicon \u27p-n molecule\u27. The resulting device is measured to reveal a rectifying I-V curve consistent with the formation of a p-n junction
A Bragg grating embedded in a slab waveguide fabricated by the implantation of high-energy light ions in KLTN substrate
Electro-optically tunable transmission grating was imprinted in potassium lithium tantalate niobate by irreversible spatial patterning of the dielectric constant. While embedded into waveguided architecture, it provides a reliable and versatile building block for opto-electronic circuitry, capable of both active switching and multiplexing. Realization of such a block is critical for the fabrication of integrated photonic circuits in electro-optic substrates by means of Refractive Index Engineering by fast ion implantation.Israel. Ministry of Science (Grant No. 3-6473)Eshkol Fellowships Foundation (Grant No. 3-6435
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