Narrow-bandwidth and stable-wavelength operation of spatial beam-combining high-power laser-diode stack configuration using a single volume Bragg grating

The spectral bandwidth was effectively suppressed and the wavelength was locked for two high-power laser-diode (LD) stacks with an external-cavity configuration that consisted of a stripe mirror and volume Bragg grating. During operation at a drive current of 100 A, the bandwidth was reduced from 2.59 to 0.31 nm (8.4-fold reduction), and a peak power output of 581 W was achieved. The power spectral density of the combined beam was increased to 1874 W/nm from 279 W/nm. The high-power-density external-cavity LD stack source showed a narrow spectral bandwidth and stable spectrum over the entire current range.