The present invention provides nanometer-sized diameter silica fibers that exhibit high diameter uniformity and surface smoothness. The silica fibers can have diameters in a range of a about 20 nm to about 1000 nm. An exemplary method according to one embodiment of the invention for generating such fibers utilizes a two-step process in which in an initial step a micrometer sized diameter silica preform fiber is generated, and in a second step, the silica preform is drawn while coupled to a support element to form a nanometer sized diameter silica fiber. The portion of the support element to which the preform is coupled is maintained at a temperature suitable for drawing the nansized fiber, and is preferably controlled to exhibit a temporally stable temperature profile.

/pdf/subwavelength-diameter-silica-wires-for-low-loss-optical-2e6789b5ae.pdf

Subwavelength-diameter silica wires for low-loss optical waveguiding

Photon upconversion of near-infrared photons is a promising way to overcome the Shockley–Queisser efficiency limit of 32% of a single-junction solar cell. However, the practical applicability of the most efficient known upconversion materials at moderate light intensities is limited by their extremely weak and narrowband near-infrared absorption. Here, we introduce the concept of an upconversion material where an organic near-infrared dye is used as an antenna for the b-NaYF4:Yb,Er nanoparticles in which the upconversion occurs. The overall upconversion by the dye-sensitized nanoparticles is dramatically enhanced (by a factor of ∼3,300) as a result of increased absorptivity and overall broadening of the absorption spectrum of the upconverter. The proposed concept can be extended to cover any part of the solar spectrum by using a set of dye molecules with overlapping absorption spectra acting as an extremely broadband antenna system, connected to suitable upconverters.

/pdf/broadband-dye-sensitized-upconversion-of-near-infrared-light-19zr1jslko.pdf

Broadband dye-sensitized upconversion of near-infrared light

Directionally solidified eutectic ceramic oxides

Borate glasses are the technologically important class of glasses and play a significant role in various applications. Borate glasses contain planar BO3 groups as structural units, rather than tetrahedral SiO4 groups. The oxygen atoms are, as in SiO2, again connected to two network-forming atoms, in case of boron. The radial distribution analysis describes the B2O3 glass structure as consisting of boroxol rings, that is, planar rings containing three boron atoms and three oxygen atoms. The network forming of the B2O3 and the SiO4 is affected with the addition of some metal cation additives Pb, Zn, Cd, and so forth. These additives also work as a network modifier and a nucleating agent for crystallization of glass. Therefore, the optical properties of the borate glasses have been changed significantly.

https://downloads.hindawi.com/archive/2012/428497.pdf

A Review on Infrared Spectroscopy of Borate Glasses with Effects of Different Additives

Rare-earth-doped transparent glass ceramics

1 Glass properties 2 Gradient index glass 3 Laser glass 4 Nonlinear optical glass 5 Magneto-optical glass

/pdf/glasses-for-photonics-8629s679u6.pdf

Glasses for Photonics

1. Glass properties 2. Gradient index glass 3. Laser glass 4. Nonlinear optical glass 5. Magneto-optical glass.

Yoshiyuki Asahara

Papers

Glasses for Photonics

Glasses for Photonics

Glasses for Photonics: Magneto-optical glass

Glasses for Photonics: Laser glass

Glasses for Photonics: Nonlinear optical glass