Four-level multiply doped rare earth laser system

A system for producing an optical gain, the system comprising:

• a. a pump light source;
• b. a halide glass host operably connected to receive energy from said pump light source, said host having a light conducting path doped with thulium, holmium and at least one rare earth from the group consisting of europium and terbium in respective amounts sufficient to produce an optical gain from energizing the thulium to a .sup.3 H.sub.4 state to produce an optical gain by a .sup.3 H.sub.4 -.sup.3 F.sub.4 transition and a gain in the regions of 1.47 .mu.m, with subsequent energy transfer from the .sup.3 F.sub.4 state of the thulium to a .sup.5 I.sub.7 state of the holmium, and energy transfer from the .sup.5 I .sub.7 state to the rare earth.

A method of making a doped fluoride laser comprising the steps of:

• forming an optical fiber having a core, a cladding a first endface and a second endface, from a fluoride glass containing zirconium, barium, lanthanum, aluminum, sodium, thulium, holmium, and at least one rare earth dopant selected from the group consisting of europium and terbium, and
• energizing said optical fiber the thulium to a .sup.3 H.sub.4 state to produce an optical gain in a region of 1.47 .mu.m.

A system for producing an optical gain comprising a pump light source and further comprising a core comprised of multiple individual optical fibers of the fluorides of zirconium, barium, lanthanum, aluminum and sodium and a first cladding surrounding the core, at least one of said fibers being doped with thulium, holmium and at least one rare earth from the group consisting of europium and terbium.

A system for producing an optical gain, the system comprising:

• a. a pump light source;
• b. a host operably connected to receive energy from said pump light source, said host having a light conducting path doped with thulium, holmium and dopant means for depopulating the .sup.5 I.sub.7 state of the holmium in respective amounts sufficient to produce an optical gain from energizing the thulium to a .sup.3 H.sub.4 state producing optical gain by a .sup.3 H.sub.4 -.sup.3 F.sub.4 transition and a gain in a region of 1.47 .mu.m, with subsequent energy transfer from .sup.3 H.sub.4 state of thulium to a .sup.5 I.sub.7 state of the holmium, and energy transfer from the .sup.5 I.sub.7 state to the dopant means for depopulating the .sup.5 I.sub.7 state of the holmium.