High power high bandwidth laser diode driver for next generation laser projectors

Employed in projection domes or in general, applications involving spherical surfaces, like professional flight simulators or automobile head-up displays, laser projectors offer great benefits over techniques involving liquid crystals or digital mirror devices. With the development of red and especially blue laser diodes with output powers in the range of several Watts, new prospects have been opened for compact and cheap laser projectors by direct modulation of the lasers with the pixel rate in scanning systems. In this paper, the requirements and challenges for the laser driver circuits are highlighted. For displaying high definition graphics and video resolutions with pixel rates above 100 MHz, the drivers need to provide very high bandwidth broadband modulation capability. Additionally high output currents in the Ampere region are required when driving high power laser diodes. Focusing on the parasitic effects of the laser diodes packages and the interconnection between drivers and lasers, restrictions and solutions for achieving the combination of these two requirements are shown. A 1.5 A, 100 MHz driver module which was developed under derived design rules is presented and test results are given for high power diodes in TO-Can and C-Mount packages.