Gain superposition and thermal management optimization in high pump power lasers using tandem Nd:MgO:LiNbO3 crystals

This paper presents a tandem dual Nd:MgO:LN laser system employing a dual-end thermally boosted pumping scheme to improve thermal management under high pump power conditions. Based on theoretical studies of pump reabsorption and gain superposition effects, a laser dynamical model for the dual-crystal structure is established, simulating the temporal evolution of intracavity photon density and population inversion density to optimize resonator parameters. A three-dimensional thermal conduction model further confirms that this configuration mitigates thermal effects in the gain medium. Experimentally, at an absorbed pump power of 45.05 W, the system delivers 7.59 W of single-wavelength 1084 nm output while fully suppressing 1093 nm lasing, achieving an optical-to-optical conversion efficiency of 16.85 %, and a power stability of 0.37 % (RMS). The beam quality is M2 X = 1.56 and M2 Y = 1.59. The dual-crystal tandem design addresses thermal limitations in single-crystal structures, extending the operational power range from 34.78 W to 45.05 W while maintaining stable 1084 nm emission. The gain superposition effect contributes to enhanced output power performance. This study provides an effective approach for thermal management and gain optimization in Nd:MgO:LN crystal laser systems under high pump power conditions.