Design and output performance simulation of a novel 561 nm medical yellow laser

Yellow lasers have important applications in biomedicine, ophthalmology and dermatology. The aim of this research is to construct a reliable yellow laser source for the laser therapy of macular degeneration by photocoagulation. Based on the thermal-lensing approximation and the ABCD matrix of Gaussian beam's propagation, a Z-type cavity insensitive to thermal lens is designed. Coating design is very important for efficient oscillating of the 1123 nm line with low gain, which should win the competition against the more efficient 1064 nm, 1320 nm and 946 nm lines. With the LASCAD software, the optimized output coupling was obtained based on the designed cavity and coating. Under the output coupling T_{1123 nm} = 10%, the incident pump power P_in = 30 W, and the beam quality factor M² = 2.0, the maximum output power P_out = 5.9 W was achieved, corresponding to an energy conversion efficiency of 19.7% and a slope efficiency of 20.4%. By frequency doubling with a KTA nonlinear crystal, a maximum output power of 2.6 W was got according to the model proposed by Smith. The experimental investigation is in progress.