Kilowatt-class single-frequency fiber sources (Invited Paper)

Abstract

We discuss the dramatic development of high-power fiber laser technology in recent years and the prospects of kilowattclass single-frequency fiber sources. We describe experimental results from an ytterbium-doped fiber-based multihundred-watt single-frequency, single-mode, plane-polarized master-oscillator power amplifier (MOPA) operating at 1060 nm and a similar source with 0.5 kW of output power, albeit with a degraded beam quality (M² = 1.6) and not linearly polarized. Experiments and simulations aimed at predicting the Brillouin limit of single-frequency system with a thermally broadened Brillouin gain are presented. These suggest that single-frequency MOPAs with over 1 kW of output power are possible. In addition, the power scalability of a simple single-strand fiber laser to 10 kW is discussed.