Laser diodes are preferred light sources for compact non-scanning imaging laser radar systems due to their small volume
and easiness to be integrated. Therefore, lots of present studies focus on research of modulation characteristics of highpower
laser diodes. A high-frequency modulated driver for a compact non-scanning imaging laser radar system is
described in this paper. It is based on linear constant current theory and can modulate a high power laser diode quasi-continuously.
A high-speed operational amplifier is used to drive a power MOSFET, which can take full advantages of
the power MOSFET–low driver current and good dynamic characteristics. In addition, an operational amplifier and PI
(Proportion-Integration) control are applied in a negative feedback network to improve the current stability further. In
order to avoid damaging the laser diode, a slow start circuit and over-current protection circuit have also been designed.
The maximum current of the over-current protection circuit can be set according to the requirement. In addition, the
power supply can also be switched between CW and QCW operating modes. When the high power semiconductor laser
is modulated by large signal, some nonlinear effects will occur such as turn-on delay, relaxation oscillation and
modulation chirp. Some theoretical analysis and experimental research on some nonlinear effects have also been done.
Experimental results are consistent with theoretical analysis by using this driver for a 1W GaAs quantum well laser.