Suppose we build two quantum well devices ((1) and (2)) to emit red and blue light. 1) Draw the potential barrier across S1-S2-S1 (5 pts); 2) When operated separately, which one emits red light and which one emits blue light? Why? (15 pts) 3) When operated in cascade (pump/emitter), which one can serve as the "pump" to incident light (I) onto the "emitter" to create light emission (e)? Why