An led consists of a planar piece of semiconductor with complex index of refraction 3.4+0.15i. the embedded p-n junction generates photons of 10=1550nm, which travel through 1.1um of semiconductor before exiting into air. concentrating first on the propagation within the material: (a) assuming for this part that propagation is normal to the interface, calculate the fraction of photons reaching the air interface. now, at the air interface some photons are reflected and some are transmitted. (b) what fraction of photons are reflected at normal incidence? at this point you may ignore the imaginary part of the refractive index. (c) calculate the critical angle for this interface. (d) calculate the angle of minimum reflection