1) We want to design a heterojunction InP / InGaAsP / InGaAs LED for 1.3 m emission with an area A = 0.01 mm2 and an output optical power Pout = 10 mW. The maximum injected charge density in the active InGaAsP layer is n = 5 x 1017 cm-3 . The effective refractive index of the heterostructure is 3.5 and the refractive index of the encapsulation material is 1.5. Evaluate the thickness of the active region assuming the radiative lifetime is 3 ns and external quantum efficiency is 40%. (You can assume that the extraction is only affected by the reflection losses, therefore extraction efficiency can be assumed to be equal to (1- Reflectance). To simplify the calculations, you can assume that the photons are only hitting the boundaries at normal incidence)