An optical transmission system is provided comprising a thulium doped optical fiber, a light emitting pump device optically coupled to the thulium doped fiber, and a Raman amplifier fiber optically coupled to the thulium doped optical fiber. The light emitting pump device in combination with the thulium...http://www.google.de/patents/US6556342?utm_source=gb-gplus-sharePatent US6556342 - Thulium doped fiber pump for pumping Raman amplifiers
