With the application of long-distance systems becoming more and more extensive, our company's self-developed middle stage access (MSA) EDFA, middle stage access (MSA) EDFA can effectively solve the insertion loss caused by DCM and OADM, offset the DCM and OADM bands. The resulting insertion loss reduces the additional degradation of the system OSNR. C-band optical signal overall amplification Covering the wavelength range of 1528 ~ 1565nm Support systems to achieve different cross-section radio repeater transmission Wide operating wavelength range:1528nm~1565nm Low noise figure: typ 5dB Excellent gain flatness Multiple operating modes: AGC adjustable Gain APC output is adjustable ACC voltage adjustable Mid-stage access for DCM or OADM Offset the insertion loss introduced by DCM Reduce the additional degradation of system OSNR Optional OSC channel for remote management MON port, on-line monitoring optical power and OSNR Middle stage access (MSA) EDFA models include an additional mid-stage port designed for insertion of a Dispersion Compensation Management (DCM) unit without its inherent insertion loss. The design of these models maximizes the DCM benefits to increase deployment flexibility.New placement options require fewer amplifiers in the link, and they can open the door to applications that were not possible with older technology.