Amplification and Lasing Characteristics of Tb3+-doped Fluoride Fiber in the 0.54 µm Band

The amplification and laser performances of a Tb 3+ -doped fluoride fiber (TBDF) operating in the 0.54 µm band, with 488 nm bi-directional pumping, have been investigated. We have analysed the gain characteristics of the 5 D 4 → 7 F 5 transition of Tb 3+ based on rate equations. It was clarified that the excited state absorption of the pump light dominates the gain characteristics for a TBDF, and improved gains of 8.3 and 15.5 dB were successfully attained for single and double-cascaded TBDF amplifiers with bi-directional pumping, respectively. In addition, we have demonstrated CW lasing operation at 542.8 nm with a TBDF laser for the first time.