An optical beam delivery device is configured to generate, from an optical beam, selectable intensity profiles. The device has a first length of fiber having a first refractive index profile (RIP), and a second length of fiber having second RIP that is different from the first RIP. The second length of fiber includes coaxial confinement regions arranged to confine at least a portion of an adjusted optical beam. The confined portion corresponds to an intensity distribution of different intensity distributions. The intensity distribution is established by a corresponding state of different states of perturbation that is applied to the device such that the confined portion is configured to provide, at an output of the second length of fiber, a selected intensity profile of the selectable intensity profiles.