University of Southampton

Spi Lasers UK Limited

Jayanta Kumar Sahu

David Neil Payne

Michael Kevan Durkin

Peter George Robin Smith

Mikhail Nickolaos Zervas

Corin Barry Edmund Gawith

Fabio Ghiringhelli

Stephen Roy Norman

Faisal Rafiq Mahamd Adikan

Andrew Simon Webb

Louise Mary Brendan Hickey

Andy Piper

Andrew Michael Gillooly

A method of producing a planar substrate having waveguide channels, which method comprises: (i) providing a tube () of a substrate material; (ii) depositing silica layers () on the inside of the tube (), the silica layers () being doped with a photosensitive material; (iii) drawing the tube () so that the cross-sectional size of the tube () is reduced; (iv) before or after the reducing of the cross-sectional size of the tube (), causing the tube () to collapse into a flat shape by applying a low pressure to the tube, whereby the deposited silica layers together form a photosensitive silica layer (); (v) cutting to required lengths the tube () which has been collapsed and reduced in cross-sectional size; and (vi) using laser writing to define waveguide channels in the cut lengths of the tube () and thereby to produce the planar substrate having the waveguide channels.

Method of fabricating a planar substrate having optical waveguides

In one embodiment, a photo-darkening resistant optical fiber includes a waveguide having a numerical aperture less than 0.15. The waveguide includes a core having a refractive index nand a pedestal having a refractive index n, and wherein the fiber includes a first cladding having a refractive index nsurrounding the pedestal, wherein nis greater than n, nis greater than n. The core includes silica, a concentration of alumina of between approximately 0.3 to 0.8 mole percent, a concentration of phosphate of substantially 15 mole percent, a concentration of ytterbium substantially in the range 20000 to 45000 ppm. The pedestal can include silica, phosphate and germania. The core can have substantially zero thulium dopant.

Apparatus for providing optical radiation

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Southampton, United Kingdom

Jayanta Kumar Sahu