Stable, single-(array)-mode operation from phase-locked, interferometric arrays of index-guided AlGaAs/GaAs diode lasers

Abstract
Single‐array‐mode (L=8) oscillation is achieved with virtually diffraction‐limited beams to three times above lasing threshold, and with beamwidths 1.5 times the diffraction limit at 4.7 times above lasing threshold and 130 mW output power per uncoated emitting facet. The arrays are 10/11‐element wide‐waveguide‐interferometric (WWI) AlGaAs/GaAs lasers grown by liquid‐phase epitaxy over channeled substrates. Selection of the L=8 mode is a consequence of two mode‐dependent loss mechanisms: transverse antiguiding between elements and radiation losses in the interferometer. Near‐field pattern analysis indicates that the (high‐order) array mode is self‐stabilizing with increasing drive above threshold. Simple means of achieving single‐lobe operation are discussed.