4th Laser Ceramics Symposium (LCS): International Symposium on Transparent Ceramics for Laser is a successive one just after the previous editions in Poland (2005), Japan (2006), and France (2007). Since laser output was achieved by using Nd:YAG transparent ceramics as gain media, transparent ceramics for laser has been becoming more and more attractive and much progress has been made in the past decade. However, understanding of the effects of raw powders, forming and sintering on the final microstructure and optical properties is a solid topic for further promotion of laser ceramics and other transparent ceramics. The aim of this symposium is to gather scientists, engineers, students, and those who devote themselves to laser ceramics and laser device to discuss these challenging issues and share their new results from different aspects.