Controlling the output optical power of a laser diode using a PID loop.

Using the information(current/voltage) given by the photodiode (which is encapsulated with the laser diode) as an input to the PID controlling system I have to control the output optical power of the laser [login to view URL] consequence the laser diode will receive a variable current to maintain the same optical power even if the diode heats up.i would prefer the PID controller to be implemented software with the use of an arduino if possible.