Optical tuning is the manipulation of the output wavelength of
an optical device, such as a laser source, or in other word, an optical
source whose wavelength of operation can be altered in a controlled
manner. There are many applications which depend mainly on tunable
laser such as in spectroscopy, photochemistry, and optical communication.
We will conduct a study in the field of Dense Wavelength Division
Multiplexing (D.W.D.M) which is very successful in Optical
Communication. For example of (D.W.D.M) “Euro Rings” network spans
over 15,000 km and connect 41 cities, consists of 96 fiber, 80 wavelength
per fiber at 10 Gbit/sec per wavelength, so its total transmission capacity is
almost 80 Tbit/sec. To have the same success in free-space optical
communications we concern in our work to examine the interaction
between multiple monochromatic optical wavelengths with water vapour
which is the most major attenuation source in the air. We got a controllable
wavelengths scanning by using a monochromator then we use a
temperature controlled optical chamber to confine the interaction medium
and varying the water vapour contents. At the end of the chamber we
detect the number of photons for each wavelength by using interface
module and software code. We compare our experimental results with the
results of a theoretical module to conclude the optimum wavelengths in
different atmospheric conditions. We can use the resulted data to give a
reasonable feedback depend on the number of photons measurements to
drive which wavelength is suitable to increase the signal to noise ratio, and
also increase the number of wavelengths used in one (F.S.O) link which
will be a large step in the modern communication systems. |
