Spi Lasers UK Limited

Trumpf Laser Gmbh

Fabio Ghiringhelli

Mikhail Nickolaos Zervas

David Neil Payne

Malcolm Paul Varnham

Michael Kevan Durkin

Andrew Thomas Harker

Jayanta Kumar Sahu

Stephen Roy Norman

Julia Helen Shaw

Andrew Marshall

Louise Mary Brendan Hickey

Andy Piper

Andrew Michael Gillooly

An optical fibre () which has a first refractive index profile () that can be changed by heating to a second refractive index profile (), at least one first dopant () for providing the first refractive index profile, at least one concealed dopant (), and at least one mobile dopant (), wherein the mobile dopant has a molar refractivity and is present in a concentration () such as to balance a change () in the first refractive index profile induced by the concealed dopant, and has a diffusion constant () greater than a diffusion constant () of the concealed dopant, so that heating of the optical fibre causes the mobile dopant to diffuse more quickly than the concealed dopant, thereby allowing the concealed dopant and the mobile dopant to change the first refractive index profile to the second refractive index profile.

Optical fibre and optical fibre device

Apparatus for combining laser radiation ()which apparatus comprises a seed laser (), a splitter (), a plurality of amplifier chains (), a reference amplifier chain (), detection means (). demodulator means (), and phase control means (), wherein each of the amplifier chains () comprises at least one optical amplifier (), optical radiation () emitted from the seed laser () is split into the plurality of amplifier chains () by the splitter (). amplified by the plurality of amplifier chains (), interfered, detected by the detection means (), demodulated by the demodulator means (), and a signal () indicative of path length imbalance () fed back to the phase control means (), and wherein the apparatus is characterized in that the output power emitted by each amplifier chain () is at least 50 W, the bandwidth () of the seed laser () is at least 1 GHz, and the path length difference () between each amplifier chain () and the reference amplifier chain () is less than the coherence length () of the seed laser ().

Apparatus for combining laser radiation

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

Fabio Ghiringhelli