Title: Development of a Split-Disk Nd:Ceramic Amplifier for Materials Processing
Name: Changhwan LIM
Affiliation: Korea Atomic Energy Research Institute 
Time：15:00-17:00, July 19, 2019
Venue: Yizhi Hall

Abstract: A a split disk amplifier with polycrystalline Nd:YAG ceramics was developed to deliver 10J /10Hz at a 10 nsec pulse for materials processing as an alternative of Excimer laser. The Nd:YAG ceramics of 12 square disks were used as a gain medium. The dimensions of the 12 ceramic disks were 58 mm x 40 mm x 7 mm. The Nd doping concentration of each ceramic was 0.8 atomic%. The gain medium was pumped by eight Xenon flash-lamps with a bore diameter of 5 mm and an arc length of 200 mm. The electrical energy of each flash-lamp was designed up to 120 J within a 300 usec pulse duration. We also attached a cooling guide to avoid any beam distortion by the turbulence of the coolant. A small signal gain of a split disk Nd:Ceramic amplifier was measured to be more than 3 at the center of the gain medium. The output energy of the amplifier in a five-pass geometry was 6.5 J at 10 nsec, 30 Hz.

Biography: Since 1988 after Dr. Lim joined to KAERI, he has worked on the development of high power lasers and high resolution laser spectroscopy for isotope separation. He got a Ph. D from Institute of Laser Engineering, Osaka University, under the title of “Study on atomic vapor laser isotope separation of Zirconium”. Since 2004, he took charge of a new high power laser program in KAERI after transferring Japanese old laser system, named Gekko IV. He re-constructed the old Gekko-IV laser as a modified one, named KLF (KAERI Laser Facility) with SIOM and LFRC scientists. He now takes charge of KLF laboratory, HEDS research in KAERI, and since 2009, he has managed the the Korea-China cooperation project with SIOM.