Introduction to optoelectronics (II)

Abstract

Perhaps, when I started writing on this subject, I thought it would be much easier. Obviously I am not relying on existing knowledge and I'm not inventing anything new. However, it is hard to make a brief popular article, not a book, so I apologize for the possible image of lack of rigor that can give both simplify things. Well it is preferable to get easier and more readers, instead of writing something that even I know what I mean.