Laser Beam Characteristics of Optical Phased Arrays

Optical phased arrays (OPAs) are being actively developed as the next generation of high power laser systems. The coherent combination of several laser beams in tiled OPA configurations, as well as their propagation through the atmosphere has been successfully demonstrated. At the same time, only limited discussions of OPA beam formation and propagation characteristics can be found in scientific literature. This paper is intended to fill the void by providing details about OPA beam formation phenomenon, as well as by presenting the key OPA beam characteristics. The influences of several OPA characteristics, including the aperture fill factor, the number of the individual beams comprising the OPA, and the shape of the individual beams on the formation and propagation of the laser radiation are presented. We also demonstrate the impact of OPA beam phase discontinuities, such as piston phase delays between the individual beams, on the resulting properties of the OPA beams.