Fig. 1. Structure design of C＋L band RGU

Fig. 2. The relationship between wavelength and gain and NF of C band signal with different length of EDF

Fig. 3. The relationship between wavelength and gain and NF of L band signal with different length of EDF

Fig. 4. The structure of C＋L band ultra-long haul transmission

Fig. 5. Signal quality parameters of all signals at the receiving end of the system

Fig. 6. C＋L band RGU performance in the transmission system