| 摘要 |
The invention is based on the discovery that under certain conditions lasing at room temperature can be achieved in a Pr<3+>-doped fluorozirconate fibre pumped in the infrared at 1.01 mu m and 835nm, the lasing taking place in the blue (491nm), green (520nm), orange (605nm) and red (635nm and 715nm). One laser comprises a length of Pr<3+>-doped potical waveguide such as a fibre, and means for exciting the Pr<3+> ions to an energy level in the band (<3>P2, <1>I6, <3>P1, <3>P0), in which the Pr<3+> concentration is in the range substantially 50 ppm to substantially 10,000 ppm (by weight). The Pr<3+> concentration is preferably in the range substantially 200 ppm to substantially 2,000 ppm (by weight). The optical fibre is preferably a fluorozirconate fibre doped at the foregoing concentrations with Pr<3+> ions. The fibre preferably comprises a doped core clad with a further glass. The excitation means is preferably arranged to excite the Pr<3+> ions from the <3>H4 level, and this is preferably achieved by upconversion by way of the <1>G4 level, but excitation may be achieved by transfer of energy from a co-dopant. |
