A semiconductor laser has a threshold current of 25 mA and a slope efficiency of 0.25 W.A1 (measured from one output facet). What is the output power of the laser in mW when the laser is driven with a current of 57 mA? Answer: Assuming the laser emits equal powers from its two facets, what is the 'wall-plug' efficiency for converting electrical power into optical output if the voltage across the laser is 1.9 V at the forward bias current 57 mA? Express your answer as as percentage. Answer: The laser is now modulated with binary digital data by adding a 50 mA peak-to-peak signal with zero mean to the DC bias current of 57 mA. What is the extinction ratio of the modulated optical output from the laser? Give your answer in dB. Answer: