Page 356 - Electrical Properties of Materials

Optoelectronics

13 Mehr Licht

Attributed dying words of Johann Wolfgang von Goethe
I saw Eternity the other night,
Like a great ring of pure and endless light
Henry Vaughan The World

13.1 Introduction
What are optoelectronic devices? I do not think it is easy to answer this ques-
tion; as far as I know, there is no accepted definition. There was certainly a
time when people talked about photoelectronic devices. I believe they were
devices which had something to do both with photons and electrons, in partic-
ular with the interaction of light with electrons. Then there was (and still is)
electro-optics, concerned with the effect of electric fields upon the propagation
of light. So, maybe we should define optoelectronics as a broader discipline
which covers both photo-electronics and electro-optics. But what about the
interaction of light and acoustic waves, or nonlinear optics, are they part of
optoelectronics? We seem to be driven towards the definition that any modern
way of manipulating light (interpreted generously, so as to include infrared and
ultraviolet) will qualify as optoelectronics.
Some cynics have an alternative definition. They maintain that this new
subject emerged when the relevant grant-giving authorities (on both sides of
the Atlantic) came to the conclusion that they had very little money to spare for
research in the traditional subjects of photoelectronics, electro-optics, acousto-
optics, etc. So those compelled by necessity to spend a considerable part of
their time writing grant applications invented a revolutionary new subject with
a brilliant future ...
Having decided that optoelectronics is a very broad subject, the next thing
I have to do is to say that I can treat only a small fraction of it. The choice
is bound to be subjective. I shall, of course, include important devices like
junction type photodetectors, and I shall certainly talk about new topics like
integrated optics or nonlinear optics. Where I might deviate a little from the
general consensus is in choosing illustrations like phase conjugation in photo-
refractive materials or electroabsorption in quantum well structures, which I
find fascinating. I do hope though that I shall be able to give a ‘feel’ of what is
happening in this important field.