Efficient PDFA module using high-NA PbF2/InF3-based fluoride fiber

The highest reported single-pass gain coefficient of 0.36 dB/mW has been achieved using a newly developed Pr/sup 3+/-doped high-NA PbF
₂
/InF
₃
-based fluoride fiber, with a /spl Delta/n of 6.6%, a core diameter of 1.2 μm and a transmission loss of 250 dB/km at 1.2 μm. This fiber was used to construct an efficient PDFA module with a MOPA-LD. A small-signal net gain of 22.5 dB was achieved at 1.30 μm with a pump power of 23m mW.