Effects of 946-nm thermal shift and broadening on Nd ³⁺ :YAG laser performance

Abstract

Spectroscopic properties of flashlamp pumped Nd 3+ :YAG laser are studied as a function of temperature in a range from −30 • C to 60 • C. The spectral width and shift of quasi three-level 946.0-nm inter-Stark emission within the respective intermanifold transitions of 4 F 3/2 → 4 I 9/2 are investigated. The 946.0-nm line shifts toward the shorter wavelength and broadens. In addition, the threshold power and slope efficiency of the 946.0-nm laser line are quantified with temperature. The lower the temperature, the lower the threshold power is and the higher the slope efficiency of the 946.0-nm laser line is, thus the higher the laser output is. This phenomenon is attributed to the ion-phonon interaction and the thermal population in the ground state.

Linear polarization output performance of Nd:YAG laser at 946 nm considering the energy-transfer upconversion

“…[6] However, it is relatively difficult to obtain an efficient 946 nm Nd:YAG laser, due to the characteristics of the quasithree-level transition, the need for a high pump deposition density to achieve population inversion, and the extremely small stimulated emission cross section compared with those near 1064 nm and 1320 nm, [7] thereby leading to very strong thermal effects and limiting the power scaling of laser as well. [8] Several methods have been used to reduce the thermal lensing effect and improve the performance of Nd:YAG laser at 946 nm, such as using a composited laser rod, [9] efficient cooling schemes, [10,11] direct pumping and thermally boosted pumping. [12] Another factor that limits the scaling of Nd:YAG laser output is the energy-transfer upconversion (ETU) effect.…”