Continuous wave Fe:ZnSe mid-IR optical fiber lasers.

Today fiber lasers in the visible to near-infrared region of the spectrum are well known, however mid-infrared fiber lasers have only recently approached the same commercial availability and power output. There has been a push to fabricate optical fiber lasers out of crystalline materials which have superior mid-IR performance and the ability to directly generate mid-IR light. However, these materials cannot currently be fabricated into an optical fiber via traditional means.

Nitrous oxide detection at 5.26 µm with a compound glass antiresonant hollow-core optical fiber.

Laser-based gas sensors utilizing various light-gas interaction phenomena have proved their capacity for detecting different gases. However, achieving reasonable sensitivity, especially in the mid-infrared, is crucial. Improving sensor detectivity usually requires incorporating multipass cells, which increase the light-gas interaction path length at a cost of reduced stability.

Hollow core fibers for optical amplification.

Hollow core optical fibers are normally passive light transport components. In contrast, within this Letter, we numerically investigate the possibility of using them as optical amplifiers, through the adoption of a novel fiber structure. We show that optical amplification can be achieved in hollow core fibers, where the cladding region is partially doped and composed of both resonant and anti-resonant elements.

Composite material hollow antiresonant fibers.

We study novel designs of hollow-core antiresonant fibers comprising multiple materials in their core-boundary membrane. We show that these types of fibers still satisfy an antiresonance condition and compare their properties to those of an ideal single-material fiber with an equivalent thickness and refractive index. As a practical consequence of this concept, we discuss the first realization and characterization of a composite silicon/glass-based hollow antiresonant fiber.

Single-fluxon controlled resistance switching in centimeter-long superconducting gallium-indium eutectic nanowires.

The ability to manipulate a single quantum object, such as a single electron or a single spin, to induce a change in a macroscopic observable lies at the heart of nanodevices of the future. We report an experiment wherein a single superconducting flux quantum, or a fluxon, can be exploited to switch the resistance of a nanowire between two discrete values. The experimental geometry consists of centimeter-long nanowires of superconducting Ga-In eutectic, with spontaneously formed Ga nanodroplets along the length of the nanowire.

Extreme electronic bandgap modification in laser-crystallized silicon optical fibres.

For decades now, silicon has been the workhorse of the microelectronics revolution and a key enabler of the information age. Owing to its excellent optical properties in the near- and mid-infrared, silicon is now promising to have a similar impact on photonics. The ability to incorporate both optical and electronic functionality in a single material offers the tantalizing prospect of amplifying, modulating and detecting light within a monolithic platform.

Silicon p-i-n junction fibers.

Flexible Si p-i-n junction fibers made by high pressure chemical vapor deposition offer new opportunities in textile photovoltaics and optoelectronics, as exemplified by their photovoltaic properties, gigahertz bandwidth for photodetection, and ability to waveguide light.

Confined high-pressure chemical deposition of hydrogenated amorphous silicon.

Hydrogenated amorphous silicon (a-Si:H) is one of the most technologically important semiconductors. The challenge in producing it from SiH(4) precursor is to overcome a significant kinetic barrier to decomposition at a low enough temperature to allow for hydrogen incorporation into a deposited film. The use of high precursor concentrations is one possible means to increase reaction rates at low enough temperatures, but in conventional reactors such an approach produces large numbers of homogeneously nucleated particles in the gas phase, rather than the desired heterogeneous deposition on a surface.

Polycrystalline silicon optical fibers with atomically smooth surfaces.

We investigate the surface roughness of polycrystalline silicon core optical fibers fabricated using a high-pressure chemical deposition technique. By measuring the optical transmission of two fibers with different core sizes, we will show that scattering from the core-cladding interface has a negligible effect on the losses. A Zemetrics ZeScope three-dimensional optical profiler has been used to directly measure the surface of the core material, confirming a roughness of only ~0.

Spontaneous waveguide Raman spectroscopy of self-assembled monolayers in silica micropores.

Advances in nanoscience are critically dependent on the ability to control and probe chemical and physical phenomena in confined geometries. A key challenge is to identify confinement structures with high surface area to volume ratios and controlled surface boundaries that can be probed quantitatively at the molecular level. Herein we report an approach for probing molecular structures within nano- to microscale pores by the application of spontaneous Raman spectroscopy.

Organosilane self-assembled monolayer growth from supercritical carbon dioxide in microstructured optical fiber capillary arrays.

Microstructured optical fibers form a new class of extreme aspect ratio templates that are well-suited for precise, designed spatial organization of materials and molecules at dimensions down to the nanoscale. The extreme aspect ratios of the nanoscale to microscale pores in the templates necessitates new approaches to fabrication of nanowires, nanotubes, and self-assembled monolayers within them. High-pressure fluids, which have lower viscosities than liquids and no surface tension, are well-suited for penetrating such extreme aspect ratio capillaries.

Microstructured optical fibers as high-pressure microfluidic reactors.

Deposition of semiconductors and metals from chemical precursors onto planar substrates is a well-developed science and technology for microelectronics. Optical fibers are an established platform for both communications technology and fundamental research in photonics. Here, we describe a hybrid technology that integrates key aspects of both engineering disciplines, demonstrating the fabrication of tubes, solid nanowires, coaxial heterojunctions, and longitudinally patterned structures composed of metals, single-crystal semiconductors, and polycrystalline elemental or compound semiconductors within microstructured silica optical fibers.