Extending Effective Area of Fundamental Mode in Optical Fibers

High power fiber lasers have become well established in many commercial realms. However, the amplification of ultrafast pulses to higher pulse energies in ytterbium-doped fibers remains very challenging due to nonlinear effects. We have demonstrated a new class of optical fibers based on resonantly enhanced leakage channels to extend the effective mode area of conventional single mode fibers by over two orders of magnitudes. This new class of fibers paves the way for a new breed of diffraction-limited kW-level ultrafast lasers, which can usher in a new age of high peak and average power ultrafast laser science as well as many new industrial applications in material processing.