Abstract: Apparatus for providing optical radiation (10) comprising a pump array (8) for providing pump radiation (7), a first pump combiner (1), and a waveguide (3), wherein the pump radiation (7) from the pump array (8) is coupled into the waveguide (3) via the first pump combiner (1), and wherein the waveguide (3) comprises a pump guide (4) for guiding the pump radiation (7), and a gain medium (5) which emits the optical radiation (10) when it is pumped by the pump radiation (7).

Abstract: Apparatus for providing optical radiation, which apparatus comprises an optical fibre (5) having a core (3), a first cladding (1) and a second cladding (2), in which the first cladding (1) has a substantially constant diameter (9) in its cross-section. The first cladding (1) can be non-circular. Advantages include more reliable cleaving, joining and splicing.

Abstract: Apparatus for material processing, which apparatus comprises a rare-earth doped fibre (1), a laser diode source (2), a short pulse laser (18) and a controller (9), wherein the rare-earth doped fibre (1) is pumped by the laser diode source (2) to provide optical radiation (10), and the optical radiation (10) emitted by the rare-earth doped fibre (1) is combined with optical radiation (11) emitted by the short pulse laser (18), the apparatus being characterised in that the controller (9) synchronizes the optical radiation (10) emitted from the rare-earth doped fibre (1) with the optical radiation (11) emitted by the short pulse laser (18) to provide a plurality of pulses (5) comprising a pre-pulse (21) and a main pulse (22), the average peak power (23) of the pre-pulse (21) being greater than the peak power (24) of the main pulse (22).

Abstract: Apparatus for providing optical radiation (10), which apparatus comprises a pump source (1) for providing pump radiation (2), and a brightness converter (3), the apparatus being characterised in that the brightness converter (3) includes a substantially rigid region along at least a portion of its length.

Abstract: An apparatus for propagating optical radiation in a first optical mode having a first spatial mode shape, and a second optical mode having a second spatial mode shape. The first spatial mode shape is different from the second spatial mode shape. The apparatus includes an optical path and a mode transformer. The mode transformer transforms at least a portion of the first optical mode to the second optical mode. The apparatus further includes components for radiation propagation such that in use at least some of the optical radiation propagates along the optical path more than once.

Abstract: Apparatus for the industrial processing of a material by a fibre laser, which fibre laser emits optical radiation, the apparatus configured such that the optical radiation forms an optical power distribution on a surface of the material, including first and second optical powers which are located at respective first and second radii from a centre of the optical power distribution and which are of substantially higher intensity than a third optical power which is located at a third radius from the centre of the optical power distribution and which is smaller than the first and the second radii.

Abstract: Apparatus for providing optical radiation (10) comprising a pump array (8) for providing pump radiation (7), a first pump combiner (1), and a waveguide (3), wherein the pump radiation (7) from the pump array (8) is coupled into the waveguide (3) via the first pump combiner (1), and wherein the waveguide (3) comprises a pump guide (4) for guiding the pump radiation (7), and a gain medium (5) which emits the optical radiation (10) when it is pumped by the pump radiation (7).

Abstract: Apparatus for providing optical radiation (15) comprising a pump source (19) and at least one first amplifying waveguide (1), characterised in that the first amplifying waveguide (1) emits optical radiation (15) in excess of 1400 nm when pumped by the pump source (19). In one embodiment, the pump source (19) comprises a plurality of laser diodes (3) and a plurality of second amplifying waveguides (2). The first amplifying waveguide (1) is pumped by the second amplifying waveguides (2). The second amplifying waveguides (2) are pumped by the laser diodes (3). The second amplifying waveguides (2) are configured to improve the beam quality of radiation emitted by the laser diodes (3). Advantageously, the apparatus can be configured such that the optical radiation (15) emitted by the first amplifying waveguide (1) has a higher brightness when the second amplifying waveguide (2) emits at a first wavelength.

Abstract: Apparatus comprising an optical fibre (1) having a waveguide (2) and at least one stress applying region (3): in which the waveguide (2) is defined by a numerical aperture; the stress applying region (3) has a depressed refractive index; the optical fibre (1) is configured such that the waveguide (2) supports at least two polarised fundamental modes, two polarised first second-order modes, and two polarised second second-order modes; the waveguide (2) comprises a gain medium (4); and the stress applying region (3), the waveguide (2)and the disposition of the gain medium (4) are such as to provide preferential guidance to at least one of the modes at an operating wavelength.

Abstract: A method of and apparatus for scale factor compensation for piezo-electric rate sensors maintains the magnitude of vibration at a primary pick-off point substantially constant to enable one of the variables of a vibrating structure--the piezo-electric charge coefficient .beta. to be determined, and thereby enables variation of the scale factor of the sensor from a calibrated value to be determined. This enables correction of the sensor output by a computational scale factor control unit to ensure that the output therefrom allows for a more accurate sensor. Thus, sensors are provided for applications requiring a higher degree of accuracy than they were previously able to provide for.