Experimental Investigation of High Power Erbium--Ytterbium Co-doped Double Clad Fibre Laser

All-fibre high power erbium--ytterbium co-doped double clad fibre lasers are proposed and demonstrated. By using different back-cavity mirrors, the different double clad fibre lasers are constructed. It is experimentally found that the output behaviour of laser can be controlled by a back-cavity mirror. The lower the reflectivity of the back-cavity mirror, the higher the output power and the high the slop efficiency. The maximum output power is about 1.6\,W and the slop efficiency is 27.6%.