Abstract:
Background High-power femtosecond fiber lasers are essential tools for advanced applications in ultrafast science, precision manufacturing, and nonlinear optics. However, achieving hundred-watt-level output while maintaining high beam quality and short pulse duration remains challenging due to nonlinear effects and transverse mode instabilities.
Purpose This work aims to develop a high-power femtosecond fiber laser system based on chirped-pulse amplification (CPA), using rod-type photonic crystal fiber as the gain medium, to achieve hundred-watt-level output with high efficiency and stable beam quality.
Methods The system adopts a rod-type photonic crystal fiber as the main amplifier. Backward pumping combined with double-pass amplification in a single rod fiber is implemented to enhance pump-to-signal conversion efficiency. Nonlinear effects are mitigated by employing a large mode area fiber, short gain length, and proper chirped-pulse management. A double-grating compressor is used for final pulse compression.
Results The amplifier achieves a pump-to-signal conversion efficiency exceeding 60%. The system delivers pulses with a central wavelength of 1033 nm, a repetition rate of 1 MHz, a single-pulse energy of 162 μJ, and a pulse duration of 233 fs. The output beam ellipticity is better than 95%. The overall pump-to-compressed-signal efficiency reaches 54%.
Conclusions The demonstrated system achieves high repetition rate, high average power, and ultrashort pulse duration simultaneously, providing a novel and practical scheme for hundred-watt-level femtosecond fiber lasers. This approach offers new opportunities for applications requiring stable, high-brightness ultrafast sources.
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