Phase locking of a two-dimensional array of CO2 waveguide lasers

Coherent lasing in a two-dimensional array of CO2 waveguide lasers pumped by a capacitive discharge is reported. The array consisted of 62 glass tubes, each with an i.d. of 5.5 mm. A plane-parallel output mirror made of GaAs was used, along with a resonator mirror consisting of parallel ZnSe plates. Diffractive exchange of light through a plane-coupling mirror oriented normal to the optical axis of the system produced phase-locking among the elements. Photographic evidence is presented of the presence of an interference pattern in the light beam of the independent sources, proving that a coherent component was achieved with the apparatus. Simple models are discussed for spacing of the elements and the mirrors to maximize the coherence and minimize the losses between elements.