High-energy mid-infrared Er,Pr:GYAP laser with LD side pumping

A high-energy LD side-pumped Er,Pr:GYAP laser is demonstrated in free-running and electro-optically Q-switched operations. In free-running mode, bonded and unbonded crystal rods deliver maximum output energies of 1.21 and 0.94 J with slope efficiencies of 9.54% and 7.44%, respectively, at a working frequency of 30 Hz and a pump pulse width of 1 ms. For the bonded crystal, a maximum pulse energy of 125 mJ and a pulse width of 33.55 ns were achieved in Q-switched operation at a repetition rate of 10 Hz. Increasing the pump pulse width reduces the conversion efficiency from free-running to Q-switched operation, revealing that amplified spontaneous emission (ASE) causes substantial energy loss during energy storage. These results demonstrate that the Er,Pr:GYAP is a promising gain medium for high-energy mid-infrared lasers.