Spectral and laser properties of Nd:YSAG single crystal

In order to solve the problem of low segregation coefficient of Nd3+ ions in YAG crystal, Sc3+ ions are used to replace some Al3+ ions in YAG, so that the YAG cell becomes bigger, thereby the segregation coefficient of Nd3+ ion increases. In this paper, the spectra and laser characteristics of Nd:YSAG single crystal are studied. The (1.5 at.%) Nd3+:Y3Sc2Al3O12 (YSAG) laser crystal is grown by Czochralski method, and X-ray rocking curve shows that the crystal quality is good. The concentration of ions in Nd:YSAG is measured by an electronic probe. The segregation coefficient of Nd3+ ion is calculated to be 0.35, which is approximately twice as much as that of Nd3+ in YAG. The absorption and emission spectra are measured, which indicates that it can be pumped by an 808 nm-laser diode (LD). The strongest emission from the transition 4F3/24I11/2 of Nd:YSAG peaks at 1059 nm with an emission cross section of 1.0310-19 cm2, and the lifetime of 4F3/2 is about 253 s, which indicates that Nd:YSAG has roughly an efficiency equal to that of Nd:YAG, but the laser upper level lifetime is longer than that of Nd:YAG, which is more favorable for Q-switched laser operation. The 808 nm-LD is used to pump Nd:YSAG rod of 2 mm2 mm6 mm, the laser operation with a threshold of 0.85 W and a maximum output power of 1.1 W is realized:the laser slope efficiency is 21.1%, and the optical conversion efficiency is 18.3%. All of the above results show that Nd:YSAG single crystal is a good solid state laser material, which is more favorable for Q-switched laser operation.