High-power laser amplifiers have attracted substantial attention in recent years, because they have stimulated research on high-field laser-matter interactions. In our laboratory, we are aiming to develop a source of electron beam by laser induced photoemission in a particle accelerator. We are therefore interested in developing suitable, high-power laser sources to efficiently generate high-energy electrons. In this thesis, the properties of femto-second and sub-nano second laser amplifiers are demonstrated and studied based on the chirped-pulse amplification (CPA) technique and flashlamp-pumped laser amplifier system, respectively. In this thesis, we investigated flash-lamp-pumped laser amplifiers with three distinct laser gain media, Nd: YAG, Nd: glass, and Er: Yb: Cr: glass. These systems adopt a pump chamber housing the gain medium with a side-pumped Kr-arc lamp. For the Nd:YAG amplifier system, the maximum output pulse energy can be higher than 4 mJ at 1064 nm with a signal gain of 109. For the Ti: Sapphire laser amplifier based on the CPA technique, the crystal was damaged before sufficient data can be obtained. However, a discussion on the already-taken data and corresponding suggestions are provided at the end of this thesis. Further experimental efforts on this subject are currently underway.