Abstract: Apparatus for controlling laser piercing of a remote material (10), which apparatus comprises: at least one piercing laser (1) for emitting laser radiation (2) for piercing the remote material (10), which laser radiation (2) is characterized by a first wavelength (16); a probe laser (3) for emitting a probe signal (4) for monitoring the piercing of the remote material (10); beam delivery optics (5) configured to direct the laser radiation (2) and the probe signal (4) onto the material (10); at least one detector (6) for detecting optical radiation (7) that is emitted or reflected by the material (10) in response to the probe signal (4); and an electronic filter (8) for filtering an electronic signal (9) emitted by the detector (6) in response to the detector (6) detecting the optical radiation (7); and the apparatus being characterized in that the probe laser (3) is configured such that the probe signal (4) is able to be modulated by a modulation signal (13); and the electronic filter (8) comprises a phase se

Abstract: A weld (3) between a first material (1) and a second material (2), the first material (1) being a first metallic material, and the second material (2) being a second metallic material, the weld (3) has a width (4) between 0.5 mm and 7 mm, the weld (3) comprises at least one microweld (8), the microweld (8) forms a welding pattern (5) defined parallel to a surface (6) of the first material (1), and the microweld (8) has a characteristic feature size (7) of between 20 ?m and 400 um.

Abstract: In one embodiment, a photo-darkening resistant optical fibre includes a waveguide having a numerical aperture less than 0.15. The waveguide includes a core having a refractive index n1 and a pedestal having a refractive index n2, and wherein the fibre includes a first cladding having a refractive index n3 surrounding the pedestal, wherein n1 is greater than n2, n2 is greater than n3. 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.

Abstract: In one embodiment, a photo-darkening resistant optical fibre includes a waveguide having a numerical aperture less than 0.15. The waveguide includes a core having a refractive index n1 and a pedestal having a refractive index n2, and wherein the fibre includes a first cladding having a refractive index n3 surrounding the pedestal, wherein n1 is greater than n2, n2 is greater than n3. 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.

Abstract: 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 n1 and a pedestal having a refractive index n2, and wherein the fiber includes a first cladding having a refractive index n3 surrounding the pedestal, wherein n1 is greater than n2, n2 is greater than n3. 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.

Abstract: In one embodiment, a photo-darkening resistant optical fibre includes a waveguide having a numerical aperture less than 0.15. The waveguide includes a core having a refractive index n1 and a pedestal having a refractive index n2, and wherein the fibre includes a first cladding having a refractive index n3 surrounding the pedestal, wherein n1 is greater than n2, n2 is greater than n3. 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.