As can be seen from the I-L curves, increases in temperature reduce the optical power that can be obtained at a given current. The laser threshold will increase exponentially with temperature as exp (T/T0), where T is the laser temperature and T0 is the "characteristic temperature" of. Based on the relation between laser temperature and the output power, a photodiode (PD) based laser temperature control system was proposed. The first parameter of interest is the exact current value at which this phenomenon takes place. In this case die bond quality.