A directly pumped, un-sensitized, holmium, quasi-two level fiber laser is
disclosed that is doped with Holmium active ions between 0.1 and 2.0
percent by atomic weight. This yields greater energy efficiency from the
laser because up-conversion losses are minimized, mismatches created by
sensitizer ions are eliminated by having no sensitizer ions, and thermal
loading of the fiber medium of the laser is thereby reduced. In addition,
the pump ratio of the fiber laser is 0.9 which yields a very low quantum
defect. The low doping percentage of holmium active ions also eliminates
any absorption of its own energy because the power of the diode pumping
source is sufficient to cause the laser to reach transparency.