High-Energy Short-Pulse Fiber Amplifier at Eye-Safe Wavelengths

Ultra Short Pulse (USP) laser technology offers compelling capabilities for the defense, medical and material processing industries. The development of this technology into commercial devices has been limited mostly by the size, cost and pulse energies provided by current USP laser systems. Fiber-based USP lasers have dramatically decreased the size of this technology, but the amplification of high energy pulses is still necessary to achieve the desired success for commercial USP laser devices. Power scaling of fiber lasers and amplifiers requires increasing the signal mode size to avoid nonlinear impairments and optical damage. Established approaches to scalability are inherently limited since the signal mode becomes progressively more unstable with effects such as mode competition and scrambling as the size increases. As described in this proposal, the capability to scale fiber amplifiers beyond the 100 μJ/pulse range, in a single polarization state, with high beam quality and in a compact form factor is achieved using higher order mode (HOM) propagation. Higher order modes have demonstrated scalable mode size with a high degree of stability in passive fibers. They are also fully compatible with existing or enhanced all-glass pump combiners and fiber fusion and assembly techniques.