Simple design rules for single-lobe operation of (evanescently coupled) index-guided phase-locked arrays of diode lasers

The author presents both a simple yet very accurate Gaussian beamwaist approximation for the fundamental mode of the symmetric slab waveguide as well as simple design criteria for virtual, sing-lobe operation of phase-locked arrays of diode lasers. Closed-form analytic expressions, involving all parameters characteristic of index-guided, uniform arrays, are determined for the condition that at least 80% of the emitted energy is contained in the main lobe when all emitters are in phase. The effects of the various array parameters on the single-lobe condition are discussed