We present a novel, compact resonator design for large-mode thin-disk lasers, producing 300 W average output power at a 1-kHz repetition rate within a cavity length of less than 5 m. High beam quality with M2x = 1.06 and M2y = 1.15 is achieved by breaking conventional mode-matching ratios and fully exploiting the disk’s soft-aperture effect. In this work, an ytterbium-doped yttrium aluminum garnet thin-disk resonator is shown to produce fundamental transverse mode lasing with a mode size approaching or surpassing the pump spot dimension. Theoretical analysis demonstrates that the proposed cavity configuration enables a thin-disk regenerative amplifier to deliver pulse energy exceeding 200 mJ at 1 kHz repetition rate with excellent beam quality.
