Bonded Nd:glass laser gain heterostructures under transverse diode pumping for thermal management in high-energy laser amplifiers

This work investigates a bonded laser gain medium to address thermal effects in high-energy nanosecond amplifiers. We propose a diode side-pumped double-bonded structure comprising one Nd-doped phosphate glass layer and two α-SiO₂, MgO, or α-Al₂O₃ crystal endcaps. A finite-element model of the pump-induced thermal effects was developed, supported by temperature, end-face deformation, and wavefront measurements. The bonded structures exhibit 30-40% and 70-80% reduction of the temperature rise, and optical path difference (OPD) compared to a single laser glass rod under pumping with 1.7 J at 4 Hz. We report the modification of the wavefront distortion in bonded gain structures owing to the crystal endcaps' properties, analyzed using our model. Additionally, we explore strategies for further thermal optimization through bonding geometry, aiming to establish guidelines to develop novel bonded gain media.