Power scaling of high power fiber lasers for micromachining and materials processing applications

Fiber-integrated high power fiber lasers (HPFLs) have demonstrated remarkable levels of parametric performance, efficiency, operational stability and reliability, and are consequently becoming the technology of choice for a diverse range of materials processing applications in the "micro-machining" domain. The design and functional flexibility of such HPFLs enables a broad operational window from continuous wave in the 100W+ power range, to modulated CW (to 50kHz prf and above), and to quasi-pulsed operation (kW/mu s/mJ regime) from a single design of laser system. A long-term qualification program has been successfully completed to demonstrate the robustness and longevity of this family of fiber lasers. In this paper we report for the first time on the power-scaling extension of SPI's proprietary side-coupled cladding-pumped GTWave (TM) technology platform to output power levels in the multi-hundred watt domain. Fiber and system design aspects are discussed for increasing both average power and peak power for CW and quasi-pulsed operation respectively whilst maintaining near-diffraction limited beam quality and mitigating non-linear effects such as Stimulated Raman Scattering. Performance data are presented for the new family of laser products with > 200W CW output power, M-2 similar to 1.1 and modulation performance to 50kHz: Furthermore, the modular, flexible approach provided by GTWave (TM) side-pumped technology has been extended to demonstrate a two-stage MOPA operating at > 400W.