ABSTRACT
Since its invention in 1960 [1], the laser has become an indispensable tool that has transformed optical science and technology over the past four decades. The important characteristics of laser light with regard to intensity, spectral purity, spatial coherence and directionality have led to the establishment of a new branch of optical science and technology now referred to as photonics and many new applications in previously unexplored areas of pure and applied science have become possible with the advent of the laser.
