i don't think so, VC SELs are specialized for this and i think this application requires more precision than would be possible by a laser diode (keeping fluctuation within 1/16 of a microwatt or less and modulating it over 256 level with 1-16 microwatts is incredibly precise). i think using a VCSEL is a better plan of attack. I also don't know if there are production units easily available for the application. (correct me if im wrong or if i have no idea what im talking about)
In my opinion, there is virtually no way to keep modulation that specific with a diode. and to calibrate a diode & driver pair to the accuracy necessary for this application would be very expensive.