Recently, the State Key Laboratory of Strong-Field Laser Physics of Shanghai Institute of Optics and Precision Machinery (SIPM), Chinese Academy of Sciences (CAS), has made progress in the research of high-frequency and high-power ultrafast lasers, and the related results were published in Optics Letters under the title "417 W, 2.38 mJ Innoslab amplifier compressible to a high pulse quality The results were published in Optics Letters under the title of "417 W, 2.38 mJ Innoslab amplifier compressible to a high pulse quality 406 fs".
Ultrafast lasers with high power, high energy, and narrow pulse widths are important for scientific research and industrial applications. Compared with neodymium-doped all-solid-state picosecond lasers, ytterbium-doped all-solid-state sub-picosecond lasers usually adopt chirped pulse amplification technology, which has higher peak power at the same pulse energy and can achieve pulse widths of less than 100 fs or even less than a cycle order by further nonlinear compression, greatly expanding the application scenarios of ytterbium-doped ultrafast lasers. Partially end-face pumped slat (Innoslab) amplifiers are one of the main means of realizing high-power ultrafast laser amplification.
Schematic of Innoslab ultrafast laser and its output parameters
In this study, the development of Innoslab ultrafast lasers in the order of hundreds of watts based on a plano-convex cylindrical mirror structure has been accomplished. By adopting the hybrid cavity structure of plano-convex mirrors, the self-excited oscillation suppression was well realized, and the high-gain and high-power Innoslab amplifier was designed and developed. The amplifier realizes the chirped pulse amplification output with an average power of 417 W and a repetition frequency of 175 kHz, and the output beam shows good pulse quality in the pulse energy range of 1.7 mJ-2.38 mJ, with a compressed pulse width of 406 fs and a standardized pulse shape without pedestal or side flap. It is the shortest pulse width of the current Innoslab laser in the millijoule energy range at hundreds of watts of average power. The evolution of the pulse is also characterized in the experiment, and it is concluded that the combined effect of the residual higher-order dispersion from the front end of the laser, the gain-filtering effect of the amplifier, the slight mismatch of the third-order dispersion between the spreader and the compressor, and the accumulated nonlinear phase shift in the amplifier achieves a high pulse-quality output, which provides a new idea for obtaining shorter pulse widths in the Innoslab amplifier. The laser will be used in applications related to high harmonic generation and micro- and nanofabrication.
