laser welding info

Since I'm not exactly sure what you mean by "how does laser welding work", I'm not going to write out a long reply. But if I did, it would all be quoted from, "welding handbook, volume 2, 8th ed." This book is put out by AWS, and contains detailed information on all the welding processes. The book costs over $100, but you might be able to find it at the right library. Hope that's helpful.