Synchronizing Frequency and Phase of Non-overlapping Laser Beams

Abstract

We present a technique for synchronizing frequency and phase of several parallel, non-overlapping laser beams. The concept provides for a so-called pilot beam whose phase front serves as a reference. Optical phase-locked loops control the frequency of the laser sources. An experiment using diode-pumped, tunable Nd:YAG ring lasers verities the concept. One application of the scheme lies in the field of optical phased arrays, leading to sources with non-mechanically steerable output beams and high brightness due to coherent power combination. Such arrays could be used advantageously as antennas in free-space laser communications systems