A highly efficient two-stage Er/sup 3+/-doped optical fiber amplifier employing an optical gate to effectively reduce ASE

Highly efficient amplification of ultrashort optical pulses is demonstrated with a two-stage Er/sup 3+/-doped optical fiber amplifier that includes an optical gate to efficiently reduce amplified spontaneous emission (ASE) generated from the first Er/sup 3+/-doped fiber. A gain of 49 dB, an amplified peak power 0f 105 W, and 1.05 nJ pulse energy are achieved for 2-Mb/s, 10-ps pulses at a total pumping power of 90 mW from 1.48- mu m LDs.<
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