Polymer-clad silica fibers for tailoring modal area and dispersion.

We demonstrate higher-order-mode (A_eff up to ∼2000  μm²) propagation in a 100 μm outer diameter pure-silica fiber with a low-index polymer jacket commonly used for fiber laser pump guidance. This simple structure obviates the need for complex designs deemed necessary for realizing large-mode-area fibers. Modes ranging from HE_1,12 to HE_1,22 were found to propagate stably over 15 m in this fiber. The index step is approximately 4 times larger than that obtained with fluorine down doping; thus the fiber supports even higher-order modes, which may have implications for building rare-earth-doped fiber lasers or achieving enhanced dispersion tunability for high-energy fiber nonlinear phenomena.