Characterization of the array modes of high-power gain-guided GaAs single-quantum-well laser arrays

The characteristics of gain-guided GaAs single-quantum-well laser arrays, using proton bombardment to confine the current flow to 11 stripes on 9-μm centers, are described. The longitudinal-mode spectrum, the spectrally resolved far-field, and the near-field of this laser array were studied experimentally up to three times threshold current. The laser arrays are found to emit at ~10 longitudinal modes corresponding to the Fabry-Perot modes of the laser. The longitudinal spectrum is current dependent. Near threshold current, the spectrum consists of a number of longitudinal modes where only the fundamental mode of the array laser. At larger current, each of the longitudinal modes is broadened and the spectrum of each longitudinal mode consists of many individual emission lines of the array modes. For each longitudinal mode, the lowest order array mode emits at the longest wavelength and the highest order array mode emits at the shortest wavelength. The wavelength separation between neighboring array modes increases with increasing mode order. Fourteen array modes are found to emit simultaneously at three times threshold current. The experimental results are in good agreement with direct array-mode analysis based on the finite-difference method