Photodarkening in active fiber or waveguide devices (e.g. lasers, amplifiers, and incoherent sources such as ASE sources) can be reduced by altering the dopant concentration along the length of the doped fiber. A fiber or waveguide device includes two or more intentionally doped fiber or waveguide sections having different concentrations of one or more dopants. The dopants provide optical gain responsive to pump radiation provided to the fiber device by a pump source. A first optical intensity in a first of the fiber or waveguide sections is greater than a second optical intensity in a second of the fiber or waveguide sections. A first dopant concentration in the first fiber or waveguide section is lower than a second dopant concentration in the second fiber or waveguide section. Thus the dopant concentration is reduced in sections of the fiber or waveguide device having a higher optical intensity. The optical intensity can be due to pump radiation and/or signal radiation. Reduced dopant concentration in regions of high optical intensity reduces photodarkening.