1. Pr^3+-doped fluoride fiber amplifier operating at 131 μm
2. Low-noise and high-power Pr/sup 3+/-doped fluoride fiber amplifier
3. Low-noise Pr3+-doped fluoride fibre amplifier
4. Y. Ohishi, T. Kanamori, T. Nishi, Y. Nishida, S. Takahashi, Proc. Int. Congr. Glass, Madrid, 1992, p. 73.
5. Y. Nishida, Y. Ohishi, T. Kanamori, Y. Terunuma, K. Kobayashi, S. Sudo, Proc. 19th Euro. Conf. Optical Communication, Montreux, vol. 1, 1993, p. 34.