A 532 nm laser fully illuminates a photodiode in series with 10 kΩ. Responsivity at this wavelength is 0.5 A/W, voltage across the resistor is 10 mV, and dark current is zero. Find incident laser power in μW to one decimal place.
Photocurrent is I=V/R=0.010/10000=10⁻⁶ A, or one microampere. Responsivity equals current divided by optical power, so P=I/0.5=2×10⁻⁶ W=2.0 μW. The wavelength only identifies which supplied responsivity to use.