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High-peak-power short-pulse fiber laser for materials processing

High-speed, high-resolution materials processing strongly benefits from optical sources that deliver high peak power in short, high-repetition-rate pulses of excellent beam quality. These sources are also of interest for achieving high average power at nonlinearly-generated wavelengths. Until recently, high peak power, high-repetition-rate pulses have only been available from solid-state lasers. Fiber lasers and amplifiers offer significant advantages over solid-state lasers in terms of size and wall-plug efficiency. This paper presents a fiber-based master-oscillator/power-amplifier (MOPA) source at 1064nm featuring 84-μm-core, polarization-maintaining Yb-doped photonic crystal fiber that generates ~20ps - 100ps pulses at variable pulse repetition frequencies (PRFs), from 10kHz to 100MHz. The flexibility in pulse format allows the source to be tailored to the application. Where peak power is critical, the PRF is reduced to achieve maximum peak power. Where average power is needed, the PRF is increased to achieve high average power. Peak powers of ~4MW have been achieved at reduced PRF (100kHz), and average powers greater than 172W have been demonstrated at high PRF (100MHz) in a linearly-polarized output beam.