Diode-pumped Tm:YAP laser operating at 2.3 µm with enhanced performance through cascade lasing

The laser diode (LD)-pumped Tm:YAP ( a -cut, 3.5 at.%) laser generated a maximum ∼2.3 µm continuous wave (CW) laser output power of ∼3 W. The higher output power benefited from the positive effect of the cascade lasing (simultaneously operating on the 3 H 4 → 3 H 5 and 3 F 4 → 3 H 6 Tm 3+ transition). It was the highest CW laser output power amongst the LD/Ti:Sapphire-CW-pumped ∼2.3 µm Tm 3+ -doped lasers reported so far. Under the cascade laser operation, the slope efficiency of the ∼2.3 µm laser emission versus the absorbed pump power increased from 13.0% to 21.4%.