There is described a multi-clad optical fiber for propagating an optical signal having at least a single mode. The multi-clad optical fiber generally has a fiber core, an inner cladding surrounding the fiber core, and at least an outer cladding surrounding the inner cladding, the multi-clad optical fiber having at least a taper portion extending along a longitudinal dimension z, the taper portion having a radial dimension progressively decreasing at a normalized slope exceeding an adiabaticity criterion of a conventional single-clad optical fiber propagating at least the single-mode across its single-mode core.