The phase-front quality of the primary spatial lobe emitted from an injection-locked gain-guided AlGaAs laser-diode array is measured by using an equal-path, phase-shifting Mach–Zehnder interferometer. Root-mean-square phase errors of 0.037 ± 0.003 wave (λ/27) are measured for the single spatial lobe, which contained 240-mW cw output power in a single longitudinal mode. This phase-front quality corresponds to a Strehl ratio of S = 0.947, which results in a 0.23-dB power loss from the single lobe’s ideal diffraction-limited power. These values are comparable with those measured for single-stripe index-guided AlGaAs lasers.
© 1989 Optical Society of America
Original Manuscript: September 19, 1988
Manuscript Accepted: June 7, 1989
Published: September 1, 1989
Donald M. Cornwell, Jonathan A. R. Rall, and James B. Abshire, "Phase-front measurements of an injection-locked AlGaAs laser-diode array," Opt. Lett. 14, 910-912 (1989)