Comparison of three-and four-mirror resonator designs of Ti:sapphire lasers

Ti:sapphire lasers are widely used in many applications in optics; the designs of three-and four-mirror resonators are the basic configurations for these systems. In this work, we analyze the advantages and disadvantages of each configuration. The aim is to construct a simple and small tunable CW laser that can be used in laser spectroscopy. Brewster-cut laser rods and asymmetrically folded arms are modeled. With the model, the stability conditions are theoretically established as well as the compensation of astigmatism for both the pump and the signal beams. As experimental results, we characterize both configurations and discuss the main differences.