Joule-Class 940-nm Diode Laser Bars for Millisecond Pulse Applications

The use of long resonators (for improved thermal and electrical resistance) and advanced facet passivation (for high power) is shown to enable Joule-class pulse emission from single passively cooled 1-cm diode laser bars emitting at 940 nm. Bars on CS-mount deliver pulse energy of 1 J at 60% power conversion efficiency within a 7-nm spectral window, under quasi-continuous wave conditions (1.2 ms 10 Hz). Robustness of device performance is confirmed via burn-in and multisite testing. Joule-per-bar performance is also maintained for conduction cooled monolithic stacked arrays, adapted for bars with long resonators. Although these packages only cool the laser bar via their rear edge, peak power, lateral far field, and spectral width remain consistent with the requirements for pumping solid state lasers and scale as predicted with self-heating. An energy density > 10 J/cm $^{\mathrm { {2}}}$ is delivered from the stack surface, for brightness >3 MW/(cm $^{\mathrm { {2}}}$ -sr).