We present an effective approach to realize a highly efficient, high-power and chirped pulse amplification-free ultrafast ytterbium-doped yttrium aluminum garnet thin-disk regenerative amplifier pumped by a zero-phonon line 969 nm laser diode. The amplifier delivers an output power exceeding 154 W at a pulse repetition rate of 1 MHz with custom-designed 48 pump passes. The exceptional thermal management on the thin disk through high-quality bonding, efficient heat dissipation and a fully locked spectrum collectively contributes to achieving a remarkable optical-to-optical efficiency of 61% and a near-diffraction-limit beam quality with an M² factor of 1.06. To the best of our knowledge, this represents the highest conversion efficiency reported in ultrafast thin-disk regenerative amplifiers. Furthermore, the amplifier operates at room temperature and exhibits exceptional stability, with root mean square stability of less than 0.33%. This study significantly represents advances in the field of laser amplification systems, particularly in terms of efficiency and average power. This advantageous combination of high efficiency and diffraction limitation positions the thin-disk regenerative amplifier as a promising solution for a wide range of scientific and industrial applications.

为了提高再生放大器输出激光脉冲的对比度，需要同时提高激光脉冲纳秒尺度的对比度和皮秒尺度的对比度。利用普克尔盒对主脉冲和预脉冲时间滤波的方法，设计了普克尔盒的双通预脉冲清洁装置，通过该装置使再生放大器输出激光纳秒尺度的预脉冲对比度提高了5个数量级；利用频谱整形方法，通过在放大器腔内适当位置插入频谱整形滤波片使得主脉冲前400 ps处的放大自发辐射对比度提高了1个数量级。最终，在双通预脉冲清洁与腔内频谱滤波共同作用下，再生放大器输出激光纳秒尺度的预脉冲对比度从4.3×10^-4提高到了6.6×10^-10，放大自发辐射对比度（主脉冲前400 ps）从5.0×10^-8提高到了5.0×10^-9。