This book has been prompted by our des ire to share with others our apprecia- tion of the harmony and beauty in a particular sphere of modern optics known as "optical phase conjugation." Practical applications of the phase- conjugated wave are likely to be far-reaching. Optical phase conjugation (OPC) combines in itself aesthetic and pragmatic attractiveness, a synthesis that has made OPC a subject of general attention. The figure presents the ap- proximate rate of publications (number of articles per year) on OPC in the world literature for recent years, the lower curve denoting the work...