A multimode optical fiber includes a central core and an outer cladding (e.g., an outer optical cladding). Typically, the optical fiber's central core is a depressed, central core having an alpha-index profile (i.e., a graded-index profile), an outer radius r1, and a maximum refractive index difference Δn1 with respect to the outer cladding. The central core's alpha-index profile has a minimum refractive index at the central core's outer radius r1 that corresponds to a refractive index difference Δnend with respect to the outer cladding. Exemplary optical-fiber embodiments may include an inner cladding having an outer radius r2 and a width w2. Exemplary optical-fiber embodiments may include a buried trench having a width w3 and an outer radius r3. Furthermore, exemplary optical-fiber embodiments may include an intermediate cladding having an outer radius r4 and a width w4.