Diffraction-limited-beam, high-power operation from X-junction coupled phase-locked arrays of AlGaAs/GaAs diode lasers

A novel type of phase-locked array is demonstrated. The device is a ten-element AlGaAs/GaAs array with both evanescent wave coupling as well as coupling via X-type junctions. The array selects and maintains operation in the highest order array mode of a ten-element device: mode L=10. Threshold currents are ∼300 mA. Diffraction-limited-beam operation is achieved to 2.8×threshold and ∼200 mW (front facet of devices with optimized facet coatings). The beam lobewidths remain under 1.5×diffraction limit to 6.3×threshold and 300 mW (both facets of uncoated devices). Near-field intensity patterns confirm the intrinsic stability of high-order array modes against gain spatial hole burning.