Patent ID: 7822080

Claim:
A fiber laser comprising: a pump source adapted to generate light; a first fiber laser optically coupled to the pump source to receive light produced by the pump source and adapted to generate a first pulsed output of light, wherein the first fiber laser includes a multi-mode fiber having a first fiber core and wherein the first fiber core is an erbium doped fiber core and wherein the first fiber laser is adapted to operate in a Q-switched mode to generate the first pulsed output; and a second fiber laser optically coupled to the first fiber laser to receive the first pulsed output, the received first pulsed output inducing the second fiber laser to generate a second pulsed output of light, wherein the second fiber laser includes a single mode fiber having a second fiber core and an inner cladding wherein the diameters of the inner cladding and the first fiber core are selected so that the output from the first fiber core is coupled into the inner cladding and wherein the second fiber core is a Thulium-doped fiber core.