Double-clad upconversion fiber laser

An upconversion fiber laser, comprising

• an optical fiber having a central core doped with an active lasing ionic species, an inner cladding surrounding said central core and having a lower refractive index than said central core, and an outer cladding surrounding said inner cladding and having a lower refractive index than said inner cladding, said active lasing ionic species capable when optically pumped of undergoing upconversion excitation,
• a high power laser diode pump source having a broad emitting aperture which is substantially wider than the diameter of said central core, said high power laser diode pump source with broad emitting aperture being selected from the group consisting of a flared-resonator-type laser diode, a monolithic flared-amplifier-type MOPA device, and a broad area laser diode, pump light emitted by said laser diode pump source optically coupled at least into said inner cladding, said inner cladding forming a waveguide for said pump light, and
• means for defining a resonant cavity containing at least a portion of said optical fiber.

An upconversion fiber laser, comprising

• an optical fiber having a central core doped with an active lasing ionic species, an inner cladding surrounding said central core and having a lower refractive index than said central core, and an outer cladding surrounding said inner cladding and having a lower refractive index than said inner cladding, said active lasing ionic species capable when optically pumped of undergoing upconversion excitation, said central core being co-doped with a sensitizer ionic species selected to facilitate said upconversion excitation of said active lasing ionic species,
• a laser-diode-based laser pump source optically coupled at least into said inner cladding, said inner cladding forming a waveguide for pump light emitted by said laser pump source, and
• means for defining a resonant cavity containing at least a portion of said optical fiber.

An upconversion fiber laser, comprising

• an optical fiber contained at least partially within a resonant laser cavity and having a central core region doped with an ionic species capable of lasing at a first upconversion wavelength, said central core region embedded in a second region of said fiber doped with an ionic species capable of lasing at a second wavelength, said second wavelength exciting upconversion in said central core region, and
• means for pumping said second region, wherein said means for pumping is a second fiber laser optically coupled to said second region.