Pulsed laser sources have become an important enabler for optical systems, primarily for LiDAR and also for spectroscopy. System specifications demand for pulse widths in the ns range and below and peak powers of 100 W and more. Such sources require a combination of dedicated laser diodes, electronics drivers and the respective module packaging. This matches ideally with FBH's core competencies in customized diode lasers with our state-of-the-art developments in high-speed circuits optimized for high powers.
On the electronics side, the high-power high-speed switching requirements are nicely in line with the other activities at FBH towards digitization of RF functions, which also rely on fast switching of high powers.
The target in the development of the drivers are shortest pulse width, highest currents and high efficiency. Next to the transistor switch realization, the main challenge is to drive the short current pulses through the board and laser parasitics into the internal diode. 3D-electrical field simulation is one tool to achieve good results.
For pulse widths down to 4 ns, 800 A peak current was reached. This results in more than 600 Watt optical output power.
With mode locked lasers, pulse widths down to 10 ps and, with gain switching, pulse widths from 250 ps to some hundred ns have been demonstrated.
In designs where high and variable repetition rates are necessary, high efficiency is key. A special driver version for such applications achieves 15 % efficiency, an about ten-fold increase compared to the conventional case.