Thermally drawn metal-insulator-semiconductor fibers provide a scalable path to functional fibers. Here, a ladder-like metal-semiconductor-metal photodetecting device is formed inside a single silica fiber in a controllable and scalable manner, achieving a high density of optoelectronic components over the entire fiber length and operating at a bandwidth of 470 kHz, orders of magnitude larger than any other drawn fiber device.

Highly-resonant wireless power transfer (HRWPT) has the potential to accelerate the adoption of purely electric (EV) and plug-in hybrid electric vehicles (PHEV) in both private and public transportation applications. Compared to conductive charging solutions, WPT provides more convenience, increased safety, and seamless integration with public infrastructure, all while achieving mains-to-battery efficiencies > 90%. Moreover, WPT enables the dynamic recharging of electric vehicles driven on electrified roadways, potentially eliminating the need to stop to recharge and reducing the size of battery packs required for longer trips. In this paper, we present an analytical framework consisting of seven high-level parameters that gives a clear picture of the fundamental limits to performance and provides tools for quickly evaluating the trade-offs between different system design choices. We show how these parameters can be related to the maximum achievable efficiency, thermal load on the resonators, and dynamic range of impedances that the power electronics must drive. Finally, we apply this framework to compare systems employing three different impedance matching network topologies popular in the research literature.

Multimaterial fiber devices share the basic functional attributes of their traditional electronic counterparts, yet are fabricated from metals, insulators and semiconductors using scalable preform-to-fiber processing methods, yielding kilometers of functional fibers. New discoveries extend the field of opportunities to nanofabrication and chemistry.

Integrating optically, electrically, and thermo-mechanically disparate materials into a fiber drawn from a preform is enabling fiber devices with unique functionalities. We present two examples: directionality-controlled radial fiber lasers and all-in-fiber chemical sensors.

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 <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 ‘p–n molecule’. The resulting device is measured to reveal a rectifying I–V curve consistent with the formation of a p–n junction. Silicon nanospheres could be of interest for applications in electronics and optoelectronics. Here, Gumenniket al. demonstrate a nanosphere fabrication process based on an optical fibre drawing technique that is able to produce p and n-type spheres paired into rectifying bispherical junctions.

We report on the fabrication of all-in-fiber capacitors with poly(vinylidene fluoride) (PVDF) as the dielectric material. Electrodes made of conductive polymer are separated by a PVDF thin film within a polycarbonate casing that is thermally drawn into multiple meters of light-weight, readily functional fiber. Capacitive response up to 20 kHz is measured and losses at higher-frequencies are accounted for in a materials-based model. A multilayered architecture in which a folded PVDF film separates interdigitated electrodes over an increased area is fabricated. This structure greatly enhances the capacitance, which scales linearly with the fiber length and is unaffected by fiber dimension fluctuations.

Ultrasound transducers have many important applications in medical, industrial, and environmental settings. On page 5327, Yoel Fink and co-workers report the realization of large-active-area piezoelectric fibers, which can be woven into extended and flexible ultrasound transducing fabrics. The back cover depicts a curved grid of piezoelectric fibers, four of which are actuated and emitting a focused acoustic wave.

We report on an all-in-fiber liquid crystal (LC) structure designed for the modulation of light incident transverse to the fiber axis. A hollow cavity flanked by viscous conductors is introduced into a polymer matrix, and the structure is thermally drawn into meters of fiber containing the geometrically scaled microfluidic channel and electrodes. The channel is filled with LCs, whose director orientation is modulated by an electric field generated between the built-in electrodes. Light transmission through the LC-channel at a particular location can be tuned by the driving frequency of the applied field, which directly controls the potential profile along the fiber.

We report on the realization of a frequency-tunable all-in-fiber liquid crystal cell with built in electrodes that is demonstrated to modulate light incident transverse to its axis.

Ultrasound transducers have many important applications in medical, industrial, and environmental settings. Large-active-area piezoelectric fibers are presented here, which can be woven into extended and flexible ultrasound transducing fabrics. This work opens significant opportunities for large-area, flexible and adjustable acoustic emission and sensing for a variety of emerging applications.

A new all-in-fiber trace-level chemical sensing approach is demonstrated. Photoconductive structures, embedded directly into the fiber cladding along its entire length, capture light emitted anywhere within the fiber's hollow core and transform it directly into an electrical signal. Localized signal transduction circumvents problems associated with conventional fiber-optics, including limited signal collection efficiency and optical losses. This approach facilitates a new platform for remote and distributed photosensing.

Photoconductive structures (PCS), embedded directly into the fiber cladding and extending its entire length, capture light emitted by a chemiluminescent material reacting with peroxide vapor flowing through the fiber core, as reported by Yoel Fink and co-workers on page 6005. The PCS directly transform this emissive signal into an electrical signal, thus facilitating a new all-in-fiber platform for remote and distributed photosensing. Image: courtesy of Yan Liang.

Photodetecting fibers of arbitrary length with internal metal, semiconductor and insulator domains have recently been demonstrated. These semiconductor devices exhibit a continuous translational symmetry which presents challenges to the extraction of spatially resolved information. Here, we overcome this seemingly fundamental limitation and achieve the detection and spatial localization of a single incident optical beam at sub-centimeter resolution, along a one-meter fiber section. Using an approach that breaks the axial symmetry through the constuction of a convex electrical potential along the fiber axis, we demonstrate the full reconstruction of an arbitrary rectangular optical wave profile. Finally, the localization of up to three points of illumination simultaneously incident on a photodetecting fiber is achieved.

We report on a photoconductive fiber that supports decaying and convex electrical potential profiles capable of localizing a point of illumination, and propose a scheme to perform distributed optical sensing.