Development of an efficient praseodymium-doped fiber amplifier

This paper describes the development of an efficient praseodymium-doped fluoride fiber amplifier (PDFA) using newly developed PbF/sub 2/-InF/sub 3/-based fluoride single-mode fiber. First, the spectroscopic properties of Pr/sup 3+/ in PbF/sub 2/-InF/sub 3/-based and ZrF/sub 4/-based fluoride glass are compared and then the fabrication of high-NA PbF/sub 2/-InF/sub 3/-based fluoride single-mode fiber is presented. The gain coefficients obtained with the developed fiber are 0.36 dB/mW with a forward pumping scheme and 0.4 dB/mW with a bidirectional pumping scheme. We use this newly developed fiber to construct two types of an efficient PDFA module. We realized a 19-in rack size PDFA module with a master oscillator/power amplifier laser diode (MOPA-LD) and a plug-in type PDFA module with a wavelength-stabilized 1.017-/spl mu/m LD and describe their amplification characteristics.