AdValue Photonics’ 2 μm fiber lasers use Tm-doped fiber to offer high output power with multiple pulse widths and spectral widths. The high output power is the result of the very high quantum efficiency of Tm-doped laser systems, and the mature technology of high-power GaAlAs laser diode pumps at 0.8 μm. In particular, Tm-doped fiber lasers can benefit from the phenomenon of cross-relaxation: because the energy of the pump photon is more than twice that of the laser transition, a single pump photon, at 0.8 μm, can lead to the excitation of two ions and generate two signal photons at 2 μm. With a sufficiently high doping concentration of Tm3+ ions (greater than 2 weight percent) in the gain medium, Tm-doped fiber lasers have shown quantum efficiency exceeding 100 percent in some experiments.