In-phase mode selection of high-power diode laser array by VBG external cavity

Phase locking of a high-power DLA in-phase mode output with a volume Bragg grating as an external cavity mirror was achieved experimentally. The linear array consisted of 49 wide-aperture diodes with a diode width of 100 μm and a spacing period of 200 μm was phase locked. Improved output beam quality in the far-field and suppressed bandwidth were demonstrated. The DLA’s single lobe output was 3.67 W for a free running paser of 15 W, the far-field divergence of the phase-locked beam was 1.47 mrad, and the spectral full width at half maximum of the output beam was suppressed from 1.7 nm to 0.17 nm.