Compact high-energy, high-repetition-rate lasers represent a crucial research field in advanced laser technology. Multiple projects, both at home and abroad, are focusing on the development of tabletop-scale, high-repetition-rate, high-energy lasers for scientific inquiry. These initiatives are designed to fulfill the requirements of high-energy-density physics research and secondary radiation sources in ultra-fast time scales (sub-picosecond pulses), or for applications in inertial confinement fusion (nanosecond pulses).

    To realize compact high-energy laser pulse output, it is imperative to employ key technologies including high-intensity pumping, efficient energy storage, and amplified spontaneous emission suppression. For the driven source, we have successfully developed a high-brightness compact structure, offering a pump intensity exceeding 16 kW/cm². In terms of efficient energy storage, we have proposed a tilted pump four-pass absorption scheme, attaining a pump light absorption close to 99%. In the aspect of chirped pulse compression, we have conducted theoretical design of a compact compressor and performed experimental verification. To mitigate gain narrowing during the amplification process, we have separately adopted the "mixed-medium amplification configuration" and "spectral inversion" schemes, achieving broadband laser output.

    Laser amplifiers are crucial for obtaining compact high-energy laser pulse outputs. We have primarily focused on innovative configurations for laser amplifier. Compared to Nd³⁺, Yb³⁺-doped gain media offer several advantages, such as higher saturation flux, longer fluorescence lifetime, and lower thermal effects, all of which facilitate the development of compact, high-energy, high-repetition-rate lasers. Based on commercial Yb:YAG crystals, we have conducted research on an active-mirror amplifier with opposite-side pumping. In this setup, the light-transmitting surface of the slab-shaped gain medium serves as a reflecting mirror, and the laser beam extracts the stored energy from the gain medium through a V-shaped folded optical path. This reflective surface also doubles as the pumping and cooling window for the gain medium, enabling efficient convective heat exchange. Utilizing an angle-encoded spatial multi-pass multiplexing architecture, we have designed an integrated technical solution capable of delivering an output energy beyond 20 J within an area of less than 2 m². Our research paves a novel way for the development of ×10 J high-energy lasers.
 

High-energy Solid-state Laser