New challenges for high energy laser technology

Recent developments in high energy laser technology and new challenges that have arisen are analyzed. Possible applications for these lasers are reviewed. In particular, the technique of coherent beam combination for diode-pumped solid-state and fiber lasers is discussed, and various beam quality evaluation methods are compared. These lasers have witnessed significant progress in the last decade, and are considered to be the next generation of high energy lasers following chemical lasers. However, fiber laser lags behind solid-state laser technology by five to ten years. Chemical lasers will still be the mainstay for output powers in the hundred kilowatt range for a long time to come.