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We report a 2 μm ultrafast solid-state Tm: Lu 2 O 3 laser, mode-locked by single-layer graphene, generating transform-limited∼ 410 fs pulses, with a spectral width∼ 11.1 nm at 2067 nm. The maximum average output power is 270 mW, at a pulse repetition frequency of 110 MHz. This is a convenient high-power transform-limited ultrafast laser at 2 μm for various applications, such as laser surgery and material processing.