Gain flatness of a 30 dBm tandem Er/sup 3+/-Er/sup 3+//Yb/sup 3+/ double-clad fiber amplifier for WDM transmission

A C-band 1 Watt dual stage Er/sup 3+//Er/sup 3+/-Yb/sup 3+/ double clad amplifier offers a versatile design for both single wavelength and WDM operations. Its features include (1) a high pump conversion efficiency, (2) an overall low noise figure over a wide signal dynamic range, and (3) a natural gain flatness (<2 dB) with a high signal-to-noise ratio which makes this device a cost-effective amplifier for optical WDM repeated transmission system operating over 1545-1565 nm.