Geometric frustration in large arrays of coupled lasers

We present a new method for phase locking several thousands of laser channels. This is achieved by incorporating all the laser channels into a common degenerate resonator that can support any transverse electric field distribution. The experimental arrangement is presented schematically in Fig. 1(A). The degenerate cavity is comprised of an Nd-Yag crystal gain medium that can support many laser channels, front and rear mirrors, and a mask of an array of N apertures arranged in a desired two dimensional lattice placed adjacent to the rear mirror. Two lenses in a 4 arrangement inside the cavity ensure that any transverse electric field distribution at the mask plane is imaged onto the front mirror plane. Coupling between the lasers is introduced by increasing the distance between the rear mirror and the mask so light diffracted from each laser is coupled into its neighbouring lasers. With such an arrangement, the coupling range, strength, and sign can be readily controlled in a calibrated manner.