4. A responsivity curve for an InGaAs photodiode is shown in the figure below. a. What is the quantum efficiency (QE) at 1000 nm wavelength? b. Suppose a photocurrent of 11.5 nA is being measured by a photodiode with a photosensitive area of 1.5 mm while being exposed to a wavelength of light at peak responsivity. What would be the light intensity? c. Using diagrams and text detail how Avalanche Photodiodes (APDS) work. Typical Spectral Responsivity (InGaAs) 1.2 Responsivity (A/W) 1.0 0.8 0.6 0.4 0.2 0.0 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 Wavelength (nm)