Highly efficient phase locking of four diode pumped Nd : YAG laser beams

We describe the mutual phase-locking of four Nd:YAG beams longitudinally en d-pumped by four fiber-coupled diode lasers. Mutual phase-locking is perfor med by two types of diffractive components located inside a telescopic Fabr y-Perot resonator. The control of the phase-locking is shown and the differ ent spatial eigenmodes connected with the pumping geometry in the resonator are theoretically and experimentally studied. 1.2 W is obtained in a singl e mode stable pattern with 30% optical-to-optical conversion efficiency in the continuous wave regime. (C) 1999 Elsevier Science B.V. All rights reser ved.