254  W laser-diode dual-end-pumped Tm:YAP InnoSlab laser

A compact laser-diode dual-end-pumped 3 at. % a-cut Tm:YAP InnoSlab laser with the output power of 254 W in 1.99 µm has been demonstrated. The slope efficiency with respect to the incident pumped power is 45.9%, and the optical-to-optical conversion efficiency is 36.5%. The RMS stability of the maximum output power is better than 0.1% in 30 min. Beam quality factors M² are 250 in the x direction and 4.7 in the y direction. Additionally, the shape of the output laser spot is rectangular.