35-DB GAIN TM-DOPED ZBLYAN FIBER AMPLIFIER OPERATING AT 1.65 MU-M

We demonstrate the first high gain rare-earth-doped fiber amplifier op erating at 1.65 mu m, It consists of ZBLYAN fiber with a Tm3+-doped co re and Tb3+-doped cladding, pumped by 1.22 mu m laser diodes, It is po ssible to achieve efficient amplification with Tm3+ ions if their ampl ified spontaneous emission (ASE) in the 1.75 to 2.0 mu m wavelength re gion is suppressed by doping Tb3+ ions in the cladding, A two-stage-ty pe fiber amplifier is constructed and a signal gain of 35 dB is achiev ed for a pump power of 140 mW. A gain over 25 dB is realized in the 1. 65 mu m to 1.67 mu m wavelength region.