[Show abstract][Hide abstract] ABSTRACT: 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 ooers the tantalizing prospect of amplifying, modulating and detecting light within a monolithic platform. However, a direct consequence of silicon's transparency is that it cannot be used to detect light at telecommunications wavelengths. Here, we report on a laser processing technique developed for our silicon fibre technology through which we can modify the electronic band structure of the semiconductor material as it is crystallized. The unique fibre geometry in which the silicon core is confined within a silica cladding allows large anisotropic stresses to be set into the crystalline material so that the size of the bandgap can be engineered. We demonstrate extreme bandgap reductions from 1.11 eV down to 0.59 eV, enabling optical detection out to 2,100 nm.
[Show abstract][Hide abstract] ABSTRACT: The state of the art of silicon optical fibers fabricated via the high pressure chemical deposition technique will be reviewed. The optical transmission properties of step index silicon optical fibers will be presented. In addition, alternative complex fiber geometries that permit sophisticated control of the propagating light will be introduced.
Asia Communications and Photonics Conference; 11/2013
[Show abstract][Hide abstract] ABSTRACT: Deposition techniques that can uniformly and conformally coat deep trenches and very high aspect ratio pores with uniform thickness films are valuable in the synthesis of complex three-dimensionally structured materials. Here it is shown that high pressure chemical vapor deposition can be used to deposit conformal films of II–VI semiconductors such as ZnSe, ZnS, and ZnO into high aspect ratio pores. Microstructured optical fibers serve as tailored templates for the patterning of II–VI semiconductor microwire arrays of these materials with precision and flexibility. In this way, centimeters-long microwires with exterior surfaces that conform well to the nearly atomically smooth silica templates can be fabricated by conformal coating. This process allows for II–VI semiconductors, which cannot be processed into optical fibers with conventional techniques, to be fabricated into step index and microstructured optical fibers.
[Show abstract][Hide abstract] ABSTRACT: John V. Badding and co-workers demonstrate on p. 1461 the ability to fabricate silicon p-i-n junctions within high aspect ratio optical fibers, and which exhibit photovoltaic response. These structures are flexible, even when removed from their silica glass templates, despite their crystalline nature. Junctions of up to one meter ength have been fabricated, but also a Si wire with a length of over 10 meters has been made. This Si wire can be wound onto a spool and even woven into a fabric. With further development, these fibers can be useful for textiles and other woven fabric applications.
[Show abstract][Hide abstract] ABSTRACT: In-doped Ga nanowires 150 nm in diameter and 6mm in length have been
formed in silica nanocapillaries. X-ray fluorescence and diffraction
measurements performed at the Advanced Photon Source have been used to
characterize their chemical composition and crystal structure.
Investigation of the low temperature transport properties of these wires
reveals a two stage superconducting transition. Magnetoresistance
measurements are suggestive of vortex trapping in the wire. The X-ray
fluorescence measurements suggest phase separation in the capillaries
into Ga nanodroplets and In-Ga eutectic wires. A model to explain the
vortex trapping consistent with this observation is being developed.
[Show abstract][Hide abstract] ABSTRACT: Superfluidity, as superconductivity, cannot exist in a strict
one-dimensional system. However, the experiments employing porous media
showed that superfluid helium can flow through the pores of nanometer
size. Here we report a study of the flow of liquid helium through a
single hollow glass fiber of 4 cm in length with an open id of 150 nm
between 1.6 and 2.3 K. We found the superfluid transition temperature
was suppressed in the hollow cylinder and that there is no flow above
the transition. Critical velocity at temperature below the transition
temperature was determined. Our results bear some similarity to that
found by Savard et. al.  studying the flow of helium through a
nanohole in a silicon nitrite membrane. M. Savard, G.
Dauphinais, and G. Gervais, Phys. Rev. Lett. 107, 254501 (2011)
[Show abstract][Hide abstract] ABSTRACT: The paper reports on pursing a different, potentially complementary vision of all-fiber optoelectronics in which light can be generated, modulated, and detected within the fiber itself. Fiber devices are in general valued for their robustness, simplicity, and ability to integrate seamlessly with existing fiber infrastructure. If the light never leaves the fiber, for example, difficulties associated with modal and impedance mismatches between fibers and planar semiconductor waveguides do not need to be overcome. Fiber lasers also integrate naturally with fibers, whereas using direct gap semiconductor lasers on chip remains an ongoing challenge. Semiconductor fiber fabrication and adding optoelectronic function to fibers are also discussed.
Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC/NFOEC), 2013; 01/2013
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: We experimentally demonstrate cross-phase modulation (XPM) on a subpicosecond timescale in a hydrogenated amorphous silicon-core, silica-clad optical fiber. Significant 10nm shifts in the probe wavelength are demonstrated through Kerr-induced refractive index changes.
Information Optoelectronics, Nanofabrication and Testing; 11/2012
[Show abstract][Hide abstract] ABSTRACT: We present a silicon antiresonance reflecting optical (ARROW) fiber that has power dependent transmission properties. When the throughput power exceeds a nominal value the transmission bands close and the fiber can no longer transmit light.
Information Optoelectronics, Nanofabrication and Testing; 11/2012
[Show abstract][Hide abstract] ABSTRACT: Laser annealing of an optical fiber with an amorphous silicon core is demonstrated. The annealing process produces a fiber that has a highly crystalline core, whilst reducing the optical transmission losses by ~3 orders of magnitude.
[Show abstract][Hide abstract] ABSTRACT: The nonlinear transmission properties of hydrogenated amorphous silicon core
fibers are characterized for short pulse propagation. The influence of the material
quality and core size will be discussed in relation to device performance.
[Show abstract][Hide abstract] ABSTRACT: We experimentally demonstrate cross-phase modulation (XPM) in a hydrogenated amorphous silicon-silica optical fiber. Additional numerical analysis shows that shifts in the probe wavelength are induced by the pump indicating potential for Kerr based switching applications.
[Show abstract][Hide abstract] ABSTRACT: We explore the thermal nonlinearity in a-Si:H microcylindrical resonators fabricated from the silicon optical fiber platform. In particular, using a pump/probe technique, we determine the thermal response time and infer the material loss coefficient.
[Show abstract][Hide abstract] ABSTRACT: The nonlinear transmission properties of two hydrogenated amorphous silicon fibers with core diameters of 5.7μm and 1.7μm are characterized. The measured Kerr nonlinearity, two-photon absorption and free-carrier parameters will be discussed.
[Show abstract][Hide abstract] ABSTRACT: The proof-of-concept of an infrared imaging tip by an array of infrared waveguides tapered as small as 2 μm is demonstrated. The fabrication is based on a high-pressure chemical fluid deposition technique to deposit precisely defined periodic arrays of Ge and Si waveguides within a microstructured optical fiber template made of silica to demonstrate the proposed concept at wavelengths of 10.64 µm and 1.55 µm, respectively. The essential features of the imaging system such as isolation between adjacent pixels, magnification, optical throughput, and image transfer characteristics are investigated. Near-field scanning at 3.39 μm wavelength using a single tapered Ge core is also demonstrated.
[Show abstract][Hide abstract] ABSTRACT: ZnSe fibers are fabricated using air-silica photonic band-gap optical fiber as high-pressure microfluidic templates for semiconductor growth via chemical deposition. We examine their transmission properties over a wide spectral range.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate an array of tapered Ge-core/ZnSe-cladding waveguides in a silica fiber matrix for infrared image transfer and a pixel magnification of 3.5 x at 3.39 mu m and 10.64 mu m wavelengths. The structure was synthesized by a high-pressure chemical vapor deposition technique to deposit the semiconductor waveguides within the holes of a silica based microstructured optical fiber. The core/cladding structure reduces the optical propagation loss through the waveguides, and good isolation between the pixels is demonstrated. With further material improvements, these structures could be useful for applications such as infrared endoscopic imaging. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4734787]