4.32 Laser diode efficiencies Consider an InGaAsP FP laser diode operating at \( \lambda=1330 \mathrm{~nm} \) for optical communications. The threshold current is 6 mA . At \( I=25 \mathrm{~mA} \), the output optical power is 6 mW and the voltage across the diode is 1.2 V . Calculate external quantum efficiency (QE), external differential QE, power conversion efficiency, and the slope efficiency of the diode. What is the forward diode current that gives an output optical power of 3 mW ?