Short-Pulse High-Power Operation of GaSb-Based Diode Lasers

We report on the short-pulse high-power operation of GaSb-based diode lasers emitting in the 1.95- to 2.2-mum wavelength range. Both epi-side-down mounted broad-area lasers and epi-side-up mounted ridge waveguide lasers, sharing the same active region and epitaxial layer structure, have been studied. They show drastically different output power characteristics and thermal limitations in continuous wave (CW) or quasi-CW operation (long current pulses > 1 mus) due to the vastly different laser geometries and mounting configurations. However, in short-pulse operation (pulse length les 50 ns), the maximum output power density was found to be almost independent of the device geometry and the mounting technique, even though still limited by thermal rollover due to self-heating of the device active region. With the heatsink temperature set to -30degC, a maximum single-emitter output power of 22.5 W was recorded at an injection current density of 110 kA/cm
²
(50-ns pulse length), and a maximum power density at the output facet of 26.7 MW/cm
²
(30-ns pulse length) was achieved, without encountering catastrophic optical mirror damage.