| Abstract: | A noise figure of 2.9±0.4 dB, measured in a high-gain erbium-doped fiber amplifier for input signals in the range -35 to -15 dBm and for pump powers of >5.8 mW, is discussed. The spontaneous emission factor nsp was 0.99±0.09 for input signals less than -15 dBm. These low figures are attributable to the optimized fiber design and the use of a pump wavelength of 980 nm, at which erbium operates as a true three-level system. These two factors contribute to the very low (~500 μW) pump threshold seen in fiber, which permits nearly complete inversion to be achieved for the low pump powers employed |
