Studies on the pump coupling and laser feedback in double cladding fiber lasers

In this paper,the pump coupling and laser feedback in high power double cladding fiber lasers are analyzed,and some ways that should be taken to enhance the capability are also pointed.Conclusions can be drawn that the best scheme is to use side-pump with tapered fiber bundle and fiber grating as the reflector of laser.The potential of Fresnel zone plate used as the coupling device is given.In order to avoid the destruction of plane dichromatic mirror used as the laser reflector,dichromatic spherical lens with the same thickness used as the feedback of laser is proposed in optical fiber laser design for the first time.