Study On All-solid-state Lasers With Bi-doped GaAs Saturable Absorber

Diode-pumped all-solid-state lasers have been widely used in industry, military, and scientific research, not only owing to its compactness, device simplicity and low cost, but also because of its overall efficiency, high stability, etc. And with the help of intra-cavity saturable elements, such as Nd:YAG, GaAs and other semiconductor material with saturable absorption characteristics, passively Q-switching or mode-locking can be realized in all-solid-state lasers. Saturable absorbers have attracted significant attention because of their compactness, low cost and simplicity in operation.In recent years, GaAs semiconductor saturable absorber has become attractive because of the large optical nonlinearities and has been successfully used in a variety of solid-state lasers. When GaAs semiconductor saturable absorber has been used for passive Q-switches, the small amount of absorption in this region is believed to be caused by the EL2 defects. And when GaAs has been used in passively Q-switched and mode-locked lasers, it is believed that the two-photon absorption (TPA) and free-carrier absorption (FCA) effects play an important role in the pulse formation in GaAs. GaAs is a good saturable sabsorber and many efforts have been made to improve its performance. As we all know, alloying is an effective way of modifying the properties of a material, and Bismuth doping in GaAs is an effective way of modifying its electronic and optical properties. So in this thesis, by using Bi-doped GaAs as saturable absorber, which is produced by ion implantation, diode-pumped Nd:GGG lasers at 1064nm is realized for the first time, which mainly includes:In chapter 1, the developments of the solid-state lasers, passively Q-switched and mode-locked technology has been introduced; the fundamental principle of Q-switch and mode-locked lasers has also been given.In chapter 2, the mechanisms for GaAs as saturable absorber used in 1064nm lasers has been discussed and the main ways for the manufacture of the Bi-doped GaAs have been analyzed. The Bi-doped GaAs used in this paper is produced by ion implantation, and its parameters as saturable absorber have been researched.In chapter 3, by using Bi-doped GaAs as saturable absorber, a diode-pumped passively Q-swtiched Nd:GGG laser at 1064 nm has been researched. The output parameters have been compared with that of Nd:GGG laser with GaAs wafer under the same conditions. The results suggest that Bi-doped GaAs can be a promising new candidate of semiconductor saturable absorber in Q-switched laser.In chapter 4, a detailed study on the performance of the Nd:GGG laser with Bi-doped GaAs as saturable absorber has been demonstrated. The Q-swtiched and mode-locked laser with Bi-doped GaAs can generate stable pulses with almost 100% modulation depth. We do believe that the Bi-doped GaAs could be an excellent saturable absorber for diode-pumped Q-swtiched and mode-locked lasers.In chapter 5, the summarization of the thesis has been made, and the further work has also been provided.