Normal EDFA, including single channel, multi channel, Gain Block and EDFA with electric control, size of 90*70*15mm or bigger, can achieve higher gain and higher output power .  There are fixed gain EDFA and variable gain and variable gain slope EDFA.  The gain can be 10~38dB, and the power can reach 20dBm, even more than 27dBm.  Typical noise figure is about 5.5dB. This kind of amplifier, widely used in backbone network, MAN, OTN, PTN , is one of the important functional components of optical communication system.