Abstract:
Optical devices and a method for manufacturing these devices. One optical device includes a core region having a first medium of a first refractive index nl, and includes a cladding region exterior to the core region. The cladding region includes a second medium having a second refractive index n2 higher than the first refractive index nl. The cladding region further includes a third medium having a third refractive index n3 lower than the first refractive index nl . The third medium is dispersed in the second medium to form a plurality of microstructures in the cladding region. Another optical device includes a plurality of core regions including at least one core having a doped first medium, and includes a cladding region exterior to the plurality of core regions. The core regions and the cladding region include a phosphate glass.
Abstract:
In one aspect, a method is provided for molding from glass 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, molds are used, 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 provided. 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:
Preforms are obtained (900) and drawn (910). Different preforms of different materials are also obtained (920) and drawn (930). The preforms are then stacked (950) and inserted into a tube (960). The result is then draw (970) into a lightguide that can be an optical fiber or laser or amplifer.
Abstract:
The present invention relates to improved photonic crystal optical fibres that in preferred embodiments confine light to a core region of the fibre by the action of both a photonic band-gap cladding and an antiresonant core boundary, at the interface between the core and cladding. According to embodiments of the present invention, a fibre has a core (210), comprising an elongate region of relatively low refractive index, a photonic bandgap structure arranged to provide a photonic bandgap over a range of wavelengths of light including an operating wavelength of light, the structure, in a transverse cross section of the waveguide, surrounding the core and comprising elongate relatively low refractive index regions interspersed with elongate relatively high refractive index regions and a relatively high refractive index boundary at the interface between the core defect and the photonic bandgap structure, the boundary having a thickness that varies around the core to define features (265) that are substantially anti-resonant at the operating wavelength of the fibre.
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:
The present invention is directed to a fluorinated rare earth doped glass composition and method for making a glass-ceramic optical article therefrom, e.g. optical fiber waveguides, fiber lasers and active fiber amplifiers, having application in the 1300 nm and 1550 nm telecommunications windows. The inventive compositions include Pr3+and/or Dy3+ in a concentration range of between 300 - 2,000 ppmw and Ag+in a concentration range of between 500 - 2,000 ppmw; or Er3+in a concentration range of between 500 - 5,000 ppmw and Ag+in a concentration range of between 0 - 2, 000 ppmw. The monovalent silver ion provides an ionic charge balanced glass-ceramic crystal. These compositions exhibit reduced or absent rare earth ion clustering and fluorescence quenching effects in the presence of high concentrations of rare earth ion dopants.
Abstract:
Novel preforms and methods of making novel preforms are described. The preforms are suitable for being drawn into photonic bandgap optical fibres. In one form, the preform (1000) comprises a stack of elongate members comprising, in transverse cross section, a triangular close-packed arrangement of circular cross section capillaries (1020), which define interstitial regions containing solid rods (1040). The stack is supported around a relatively large capillary (1030), which defines an inner region of the stack. The stack may be adapted by varying the number of rods in any given interstitial region, in order to generate various different configurations of cladding structure, which can be made into optical fibres having surprising operational characteristics, such as a split bandgap.
Abstract:
The present invention is in the field of optical fibres. In particular, the present inventors describe hollow core optical fibres, for example hollow core photonic band-gap optical fibres. The present inventors describe examples of such fibres that guide light by virtue of a true photonic band-gap in a hollow core region having a boundary at the interface between the hollow core and a photonic band-gap cladding. In some examples, the boundary is tuned by addition of solid material during formation of a respective fibre preform (1800) to improve the performance of the resulting fibre, for example by mitigating deleterious effects such as mode coupling of light from core-guided modes to so-called boundary or `surface' modes.
Abstract:
A vertically disposed apparatus used to make core-clad optical fibers includes an inner elongated cylinder removably closed at the top and provided at the bottom with an inner exit port of a smaller diameter than the inner cylinder and an outer cylinder, disposed around the inner cylinder, removably closed at the top and provided at the bottom with an outer exit port of a smaller diameter than the outer cylinder. The inner exit port is of a smaller diameter than the outer exit port and is disposed directly above the outer exit port. The apparatus also includes a heater for heating the inner and outer cylinders and access to the inner and the outer cylinders for individually pressurizing inner and outer cylinders. The process by which the core-clad optical fibers are made includes the steps of placing a solid glass core rod into the inner cylinder of the apparatus described above, placing a solid glass cladding tube into the outer cylinder, melting the core rod and the cladding tube, quickly cooling the molten core rod and cladding tube to the drawing temperature, individually pressurizing the molten core rod and cladding tube, and drawing the core-clad optical fiber through the exit ports.