Abstract

Recently, Erbium Doped Fiber Amplifiers (EDFAs) have been intensively studied in transmission systems and Wavelength Division Multiplexing (WDM) systems of optical networks for their high ability. EDFAs have become an important component in the photonics network. The EDFAs’ slow upper state dynamics makes its gain sensitive to random burst signals, signal add/drop, and system reconfiguration in high bit rate digital transmission systems.¹ In the photonics network, the number of channels in the fiber is changed by signal add/drop or the system reconfiguration. When there is an add/drop node, the total power in the fiber is changed. Automatic gain control is required in these situations. Conventional optical automatic gain clamped (OAGC) EDFAs have been investigated to restrain the transition of the gain.^2–4 A loop is placed in a component of the conventional OAGC EDFA, which is a different route from the signal optical route. Optical oscillation is made in the loop using the amplification power of the EDF, achieving a constant gain of the signal by this oscillation. However this conventional OAGC EDFA has a high Noise Figure (NF), because its EDF maintains the output saturation state by the feed back loop light’s oscillation necessary for the constant gain.^5,6

© 2002 Optical Society of America