Abstract: A phase-engineered fiber is described for generating a cylindrically polarized beam. The fiber includes a core region, a ring region surrounding the core region, and an outer cladding region surrounding the ring region. The fiber regions are configured to cause the fiber to have a refractive index step proximate to the peak amplitude value of the mode intensity profile of an LP11 mode guided by the fiber. The refractive index step is sufficiently steep such that at least one of the cylindrically polarized TM01 and TE01 eigenmodes has an effective refractive index neff that is sufficiently separated from the respective effective refractive index of the other eigenmodes to allow coupling to the at least one cylindrically polarized eigenmode with minimal coupling to the other eigenmodes.