The invention of the laser was one of the most significant events in modern scientific and technological evolution. Since it was first invented in the 1960s, laser devices have dramatically changed the world in all aspects, from human daily life to the optical communication network and future technology development. The laser (an acronym based upon light amplification by stimulated emission of radiation) has become an integral part of modern society in communications, industrial processing, and medical treatments. Its basic principle is based on the generation and amplification of coherent radiation at both visible and invisible light frequency spectra. Being an electromagnetic wave at higher frequency, behaviors of laser light are governed by Maxwell's equations, for example when a light beam is interacting with different types of physical structures.