Abstract:
To overcome problems of fabricating conventional core-clad optical fibre from non-silica based (compound) glass, it is proposed to fabricate non-silica based (compound) glass optical fibre as holey fibre i.e. one contining Longitudinal holes in the cladding. This removes the conventional problems associated with mismatch of the physical properties of the core and clad compound glasses, since a holey fibre can be made of a single glass composition. With a holey fibre, it is not necessary to have different glasses for the core and cladding, since the necessary refractive index modulation between core and cladding is provided by the microstructure of the clad, i.e. its holes, rather than by a difference in materials properties between the clad and core glasses. Specifically, the conventional thermal mismatch problems between core and clad are circumvented. A variety of fibre types can be fabricated from non-silica based (compounds) glasses, for example: single-mode fibre; photonic band gap fibre; highly non-linear fibre; fibre with photosensitivity written gratings and other refractive index profile structures; and rare-earth doped fibres (e.g. Er, Nd, Pr) to provide gain media for fibre amplifiers and lasers.
Abstract:
A method is provided for molding from glass certain complex optical components, such as lenses, microlens, arrays of microlenses, and gratings or surface-relief diffusers having fine or hyperfine microstructures suitable for optical or electro-optical applications. Thereby, mold masters or patterns, which define the profile of the optical components, made on metal alloys, particularly titanium or nickel alloys, or refractory compositions, with or without a non-reactive coating are used. Given that molding optical components from oxide glasses has numerous drawbacks, it has been discovered in accordance with the invention that non-oxide glasses substantially eliminates these drawbacks. The non-oxide glasses, such as chalcogenide, chalcohalide, and halide glasses, may be used in the mold either in bulk, planar, or power forms. In the mold, the glass is heated to about 10–110° C., preferably about 50° C., above its transition temperature (Tg), at which temperature the glass has a viscosity that permits it to flow and conform exactly to the pattern of the mold.
Abstract:
Microstructured optical fibre is fabricated using extrusion. The main design of optical fibre has a core suspended in an outer wall by a plurality of struts. A specially designed extruder die is used which comprises a central feed channel, flow diversion channels arranged to divert material radially outwards into a welding chamber formed within the die, a core forming conduit arranged to receive material by direct onward passage from the central feed channel, and a nozzle having an outer part in flow communication with the welding chamber and an inner part in flow communication with the core forming conduit, to respectively define an outer wall and core of the preform. With this design a relatively thick outer wall can be combined with thin struts (to ensure extinction of the optical mode field) and a core of any desired diameter or other thickness dimension in the case of non-circular cores. As well as glass, the extrusion process is suitable for use with polymers. The microstructured optical fibre is considered to have many potential device applications, in particular for non-linear devices, lasers and amplifiers.
Abstract:
High index-contrast fiber waveguides, materials for forming high index-contrast fiber waveguides, and applications of high index-contrast fiber waveguides are disclosed.
Abstract:
A hollow optical fiber 10 has an intermed ate dielectric layer 12 interposed between an inner periphery side dielectric layer 11 facing a hollow core portion 10a and a metal layer 13. The inner periphery side dielectric layer 11 is formed of calcium fluoride. The intermediate dielectric layer 12 is formed of yttrium fluoride. Metal of the metal layer 13 can be prevented from dispersing into the dielectric layers 12, 11 by the intermediate dielectric layer 12 formed of yttrium fluoride. The hollow optical fiber 10 is manufactured by vapor depositing calcium fluoride on an outer peripheral surface of an acid-soluble glass tube 20 (base material), then vapor depositing yttrium fluoride on its outer peripheral surface, then vapor depositing a metal layer formed of silver, gold or the like on its outer peripheral surface, and thereafter, dissolving the glass tube 20 with acid.
Abstract:
High index-contrast fiber waveguides, materials for forming high index-contrast fiber waveguides, and applications of high index-contrast fiber waveguides are disclosed.
Abstract:
An upconversion fiber laser uses a pump source which may be another fiber laser, such as a high power, diode-laser-pumped, fiber laser. The upconversion fiber laser includes an optical fiber whose core region is doped with an active lasing ionic species capable when optically pumped of undergoing upconversion excitation, such as certain rare earth ionic species, and which is embedded in a cladding of the optical fiber. Use of a fiber pump laser can improve coupling of pump light into the optical fiber, thereby achieving higher pump intensities in the core region and improved upconversion efficiency. The upconversion fiber laser's resonant laser cavity is defined by feedback means which can include at least one reflective grating formed in the optical fiber, as well as a reflective end face of the optical fiber. Any portion of the optical fiber that lies outside of the resonant laser cavity, such as any portion beyond the integral reflective grating, may act as an optical power amplifier for the upconverted laser output. The disclosure includes other embodiments in which pump brightness can be further increased with multiple pump sources.
Abstract:
Method of manufacturing a multi-component glass cylindrical part comprising the operations of providing a vertical cylindrical cavity lined with porous membranes whose inside dimensions are very slightly larger than those of the glass cylindrical part and in which can slide a cylindrical pedestal, providing a seed mass of the glass on the pedestal, heating the seed mass until it melts, injecting a gas continuously into the porous membranes to form and maintain a layer of gas between the porous membranes and the molten seed mass preventing any contact between the molten seed mass and the porous membranes, feeding the molten seed mass from the top of the cavity by continuously dispensing a powder made up of the components of the glass, varying the composition of the powder as the cylindrical part is formed, so that the glass cylindrical part has a composition that varies in the longitudinal direction, and lowering the pedestal as the cylindrical part is formed.
Abstract:
A process for the vapor phase deposition of a fluoride containing glass on a substrate, the said fluoride containing glass containing in mole percent with a total of 100%, 30-50 PbF.sub.2, 30-50 GaF.sub.3, 0-30 ZnF.sub.2, 1-5 MF.sub.2 wherein M is Mn or Cd, 1-5 InF.sub.3, 0-10 AlF.sub.3 and 0-10 adjuvant, which involves contacting the substrate with vapors emanating from a molten bath of metallic fluorides comprising a reception bath containing in mole percent with a total of 100%, 9-26 YF.sub.3, 19-38 BaF.sub.2, 35-40 InF.sub.3, 18-25 M'Fe.sub.2 wherein M' is Mn, Cal or Zn and 0-10 adjuvant to which reception bath has been added a sufficient amount of a mixture of PbF.sub.2, GaF.sub.3 and optionally AlF.sub.3. The invention also concerns a vitreous composition deposited on a substrate, thus obtained, which is useful as a waveguide in the infrared.
Abstract:
In a method of manufacturing a cylindrical part from glass, especially but not exclusively fluorinated glass, a vertical cylindrical cavity is lined with a porous material and its inside dimensions are a few tens of microns greater than those of the part. A cylindrical pedestal constituting a support for the part slides in the cavity. An initial seed mass constituted from the glass is provided on the pedestal. The seed mass is heated until it melts and a gas is injected permanently into the porous material in order to maintain between them and the molten seed mass a layer of gas a few tens of microns thick to prevent any contact. The molten seed mass is fed continuously from the top of the cavity with the powder constituents of the glass and the pedestal is lowered as the cylindrical part is formed from the seed mass.