Abstract: High power up to 13.13mW(11.18dBm)of L-band SFS is developed and obtained,the mean wavelength is 1578.53nm,by using configuration of double-pass and highly doped erbium fiber,the power between 1570nm and 1620nm is higher than 9.38mW.It is important for many applicants such as distributed fiber grating sensing,fiber-optic gyroscope,DWDM,which expand from C-band to L-band.Combined with C-band,simultaneous output of C+L band with power of higher than 20mW.Hereinto,a fiber loop reflector made from normal coupler is used to injection the C-band amplified spontaneous emission of backward again enhanced the efficiency of LD and stability of output of fiber.Meanwhile,effects of fiber length and pump power on output,mean wavelength,stability is analysed,it is valuable to the design of SFS.