US Patent 7502391 Eye safe high power fibre laser

Apparatus for providing optical radiation includes a pump source and at least one first amplifying waveguide. The first amplifying waveguide emits optical radiation in excess of 1400 nm when pumped by the pump source. In one embodiment, the pump source can include a plurality of laser diodes and a plurality of second amplifying waveguides. In this arrangement the first amplifying waveguide is pumped by the second amplifying waveguides, the second amplifying waveguides are pumped by the laser diodes, and the second amplifying waveguides are configured to improve the beam quality of radiation emitted by the laser diodes.