Patent ID: 7502391
Filing Date: 2009-03-10
Classification: H01S

Abstract:
1. Apparatus for providing optical radiation comprising: a pump source and at least one first amplifying waveguide, wherein the pump source comprises a plurality of laser diodes and least one second amplifying waveguide; the plurality of laser diodes are configured to pump the second amplifying waveguide to provide pump radiation; the apparatus being such that the first amplifying waveguide emits the optical radiation when pumped by the pump radiation; and wherein the first amplifying waveguide comprises a first optical fibre; the first optical fibre is a multi-mode optical fibre and comprises a region comprising a first rare-earth dopant; and wherein: the second amplifying waveguide comprises a second optical fibre; the second optical fibre comprises a region comprising a second rare-earth dopant; and the pump radiation is defined by a wavelength, the apparatus further comprising a means to change the wavelength of the pump radiation emitted by the second amplifying waveguide between a first wavelength and a second wavelength, wherein the first rare-earth dopant is selected to absorb the pump radiation more strongly at the first wavelength than the second wavelength, and wherein the optical radiation emitted by the first waveguide has a higher brightness when the second waveguide emits the pump radiation at the first wavelength than when the second waveguide emits the pump radiation at the second wavelength, thereby providing a means to modulate the optical radiation emitted by the apparatus from on to substantially off.