A Coherent All-Solid-State Laser Array Using the Talbot Effect in a Three-Mirror Cavity

Lateral mode coupling in a diode-pumped Nd: YAG microchip laser array is demonstrated with a Talbot cavity for the first time. The relatively low laser gains of solid-state lasers compared with diode lasers and CO₂ lasers, to which the Talbot cavity has already been applied successfully, are solved by employing a novel auxiliary Talbot cavity configuration. A brighter twin-peak far-field pattern indicating an out-of-phase array mode, whose spot is 9.3 times smaller than that obtained by incoherent superposition of the individual microchip laser outputs, is obtained from the phase-locked microchip laser array with a mode-selecting slit. Without the mode-selecting slit, a far-field pattern with a single narrow peak is obtained, showing that the array is locked in an in-phase mode, presumably because of multiple reflections in the auxiliary Talbot cavity.