Περίληψη:
Coherent detection, as a process for demodulation of an optical signal,
is used to a great extent in modern optical communications. In some
configurations of this technique, the information which exists in the
frequency or the phase of the optical signal can be derived by using the
same beam as a carrier and as a local-oscillator signal too
(self-homodyne system).
In this communication, we present a theoretical analysis of such a
self-homodyne system, which is composed of a laser source, an
electrooptic modulator, a photodetector and all the necessary optical
components. The whole analysis is accompanied with a PC-supported
program, which offers the possibility to study the system for various
kinds of optical polarization but with the same incident optical power
on the photodetector, independently of the various optical components.
Furthermore, this program provides the possibility of changing the
respective values at will, after we have introduced direct and
alternating voltage as a signal. Finally, the study of the various
harmonics of the output signal’s spectrum gives the possibility to
discover the advantages that the circular polarization offers compared
with other kinds of polarization.
