This paper presents a novel approach for achieving high small-signal gain in laser amplifiers, focusing on a special triple-pass setup based on an ytterbium-doped yttrium aluminum garnet (Yb:YAG) crystal. The amplifier is pumped at the zero-phonon wavelength of 969 nm, optimizing absorption efficiency and reducing thermal effects. This design significantly enhances gain performance, surpassing traditional single or double-pass configurations. To comprehensively evaluate the proposed amplifier, we developed an advanced simulation model that accurately characterizes its behavior under different pumping and thermal conditions. The model incorporates amplified spontaneous emission (ASE) and its impact on overall performance. By simulating the ASE, we gain insights into the signal-to-noise ratio at a high gain and identify potential parasitic effects that could influence its efficiency. The simulation results were rigorously compared with experimental data to validate the model’s accuracy. The experimental setup involved measuring the gain and ASE characteristics of the Yb:YAG triple-pass amplifier under various pumping and thermal conditions. The comparison between simulation and experimental results showed excellent agreement, confirming the reliability of the simulation model and the efficacy of the proposed amplifier design. Our findings indicate that the triple-pass amplifier, when pumped at 969 nm, achieves a remarkable small-signal gain of around 60dB, substantially outperforming conventional single-pass designs. This work provides a robust framework for future developments in high-gain laser amplification technology. The integration of detailed ASE analysis in the simulation offers valuable insights for optimizing amplifier performance and improving the signal-to-noise ratio, contributing to the advancement of efficient and powerful laser amplifiers.