GAMMA-EFFECT - KEY INTERMODAL-DISCRIMINATION MECHANISM IN ARRAYS OF ANTIGUIDED DIODE-LASERS

By using results of the Bloch-function method applied to infinite-extent antiguided arrays, a closed-form expression has been derived, for the first time, for GAMMA, the two-dimensional array-mode confinement factor. When array modal behavior is analyzed, as the interelement-region width varies, domains of in-phase (i.e., single-lobe) array operation are found to occur periodically around the resonance points of in-phase modes. It is made clear why coupled-mode theory failed to predict how to obtain single-lobe phase-locked operation. Results of an exact analysis of a 20-element array are discussed, with the main conclusion being that the GAMMA-effect, while being the key mechanism for selecting single-lobe array operation, does not insure purely diffraction-limited beams to high powers.