Erbium-doped tellurite fiber amplifier flattens gain and broadens amplification bandwidth
Researchers at NTT Opto-electronics Laboratories (Ibaraki, Japan) have made a gain-flattened tellurite-based erbium-doped fiber amplifier (EDFA) with a flat amplification bandwidth of 76 nm and a noise figure of less than 7 dB. In a postdeadline paper at the Optical Fiber Communication conference in San Jose, CA, Makoto Yamada and colleagues reported that a newly developed low-loss tellurite-based erbium-doped fiber in a cascade configuration achieved low-noise amplification. A gain equalizer improved gain flatness. The cascade configuration incorporates an optical isolator in the 14-m-long erbium-doped fiber to improve noise characteristics. Two 1480-nm-output diode lasers pum¥the fiber. The grou¥also constructed a parallel-type amplifier with the tellurite-based EDFA and a 1450-nm-band thulium-doped fluoride amplifier. This produced a flat amplification bandwidth of 113 nm for the 1446-1483- and 1532-1608-nm wavelengths with a noise figure of less than 7.5 dB.