Gaussian beam is very often used for the transmission of information in optical wireless links. The usage of this optical
beam has its advantages and, of course, disadvantages. This work focuses on possibilities of using laser beams with
different distribution of optical intensity - Top Hat beam. Creation of the optical beam with selected optical intensity
profile will be briefly described. Optical beams will propagate through the "clear" and stationary atmosphere in the
experimental part of this work. These results will be compared with the data obtained after a laser beam is passed
through the turbulent and attenuated atmosphere. We will use an ultrasound fog generator for laser beam attenuation
testing. To create the turbulence, infra radiators will be applied. Particular results obtained from different atmospheric
conditions will be compared and using different types of optical beams will be assessed.
The paper deals with the modeling and measuring of laser beams parameters. Utilization of laser beams is intended for
example in free space optical links with the range about several hundred meters. By the help of submitted laboratory
works the students acquaint with basic parameters and basic characteristics of laser beams, modeling of laser beams, and
with suitable methods used for improvement of transmission reliability.
The laboratory exercise will be aimed on the measurement of energy and geometric properties of laser beam as well as
on the determination of wave properties. We will focus on the mentioned quantities from the sight of total irradiated
optical power, the distribution of optical intensity in laser beam profile and half width of energy equivalent beam. The
spectral characteristics of optical beam and spectral linewidth will be the part of the laboratory exercise.
The contribution has pedagogic character and it is closely adherent to the research realized at our institute. Generally we
are focused on the research of optical wireless links in atmosphere so the solved problem is from the area of current
problems of research.
A dual optical wireless test link works with two different optical wavelengths in spectral windows of 850 nm and
1550 nm. The transceivers of the link are placed on the highest peak of the Czech Central Mountains (Milesovka
Mountain) so that the transmission path is oriented almost in a vertical direction. The installation site is situated in a
locality with the harshest climate in the Czech Republic with extreme attenuation conditions. The almost vertically
oriented path of the link allows analyzing the impact of the different atmospheric layers on the signal transmission. The
monitoring of the received power and the archiving of the appropriate data are constantly provided. The relationship
between the link attenuation and the atmospheric visibility has been investigated. The results of this experiment are
The aim of this paper is to design measuring method for determining applicability of picked laser diode in the optical
wireless communications. Chosen laser diode must operate to not debase received optical signal quality and dynamics in
optical wireless link.
We are focusing on the processes in the optical links which are influenced by thermal effects. Varying laser diode's
operating temperature and thermal fluctuations in atmospheric transmission media, in which the information carried by
laser beam is propagating, are considered as the most significant thermal events in optical wireless communications.
As mentioned before, the influence of operating temperature for laser diode's light emission has to be taken into account.
The operation temperature affects on the physical properties of laser diode. Transmitting laser beam is collimated by
transmitting lens but in case of laser diode's operating temperature vary the change in irradiation characteristics can
occurs as an issue in optical wireless links because the distance between laser diode and transmitting lens can't be
adapted by the reason of laser beam divergence settings.
Atmospheric turbulence influence on spectrum and laser beam geometry of laser beam is investigated. In terms of
results' evaluation we can determine when detected signal is acceptable or it doesn't fulfill conditions for signal in
optical wireless communications.