An apparatus and process using a high-power, short-pulsed thulium laser to output infrared laser pulses delivered through an optical fiber, for cutting and ablating biological tissue. In some embodiments, the pulse length is shortened sufficiently to keep inside the stress-confined ablation region of operation. In some embodiments, the pulse is shortened to near the stress-confined ablation region of operation, while being slightly in the thermal-constrained region of operation. In some embodiments, the laser is coupled to a small low —OH optical fiber (˜100 μm diameter). In some embodiments, the device has a pulse duration of about 100 ns for efficient ablation; however in some embodiments, this parameter is adjustable.