Recently ytterbium-doped fiber laser has been widely developed. DCYDF （Double-Cladding Ytterbium Doped Fiber）was designed to meet rising demand for high-power laser. Fiber core of DCYDF is designed as signal waveguide

and inner-cladding is designed as pump waveguide. MOFs （Microstructure Optical Fibers） are single material optical fibers with a periodic array of air holes running along the entire fiber length where the guiding region is realized by breaking the lattice periodicity with a central defect. In particular the possibility of having very small or very large mode areas has been exploited to realize new fiber lasers or fiber amplifiers with higher gain than in conventional single-mode doped fibers. In this paper

microstructure D-shape and hexagon inner cladding ytterbium doped fiber was designed and fabricated based on requirements of high power fiber laser.