COMPREHENSIVE ABOVE-THRESHOLD ANALYSIS OF ANTIGUIDED DIODE-LASER ARRAYS

The effect of gain spatial-hole burning (GSHB), carrier diffusion and interelement loss on antiguided laser arrays is thoroughly analyzed, Nonresonant devices, due to the nonuniformity of the in-phase-mode near-field intensity profile, experience self-focusing and multimode operation with increasing drive level above threshold, similar to evanescent-wave-coupled devices, Resonant and near-resonant devices (i.e., resonant-optical-waveguide (ROW) arrays) display substantially uniform in-phase-mode near-field intensity profiles at all drive levels, thus not allowing excitation of high-order modes (i,e,, adjacent modes) due to GSHB at the array level, However, GSHB at the individual-array-element level eventually allows adjacent-mode lasing at high drive levels: greater than or equal to 10x fundamental-mode threshold for devices with relatively small ratio of element to interelement widths (so called fill factor): similar to 1.1; and greater than or equal to 7x fundamental-mode threshold for devices with moderate fill factor (similar to 3) and 60 cm(-1) interelement loss, (The carrier diffusion length is taken to be 3 mu m, and the index step, Delta n, is moderate: 0.02-0.03). The calculations agree well with many experimental results, and confirm the inherent single-spatial-mode stability of ROW arrays, The model also predicts that high-index-step (Delta n greater than or equal to 0.1) ROW arrays are likely to achieve in-phase-mode stability to drive levels greater than or equal to 15x threshold, powers of approximate to 3W, in beams with approximate to 70% of the energy in the main lobe, Practical design guidelines are presented.