The free space optical links have found their major application in today's technological society. The demand for quality
broadband is a must for all types of end users in these times. Because of the large jamming from wireless radio networks
in non-licensed ISM bands, the free space optical links provide bridging of some densely populated urban areas. Their
advantage is the high transmission rate for relatively long distances. However, the disadvantage is the dependence of free
space optical links on atmospheric influences. Aired collimated optical beam passes through the atmospheric
transmission environment and by its influence cause the deformation of the optical beam. Author's team decided to
construct a special measuring device for measurement of optical power in FSO link beam cross-section. The equipment
is mobile and can be rearranged and adjust according to the given location and placement of the FSO link at any time.
The article describes the individual structural elements of the measuring equipment, its controlling and application for
evaluation and adjustment of measuring steps. The graphs from optical power measurements in the beam cross-section of
professional FSO links are presented at the end.
The fiber optic sensors have a great possibilities thanks to its sizes, features and usage possibilities in measurement
engineering. Optical fiber is mostly used as a medium for the transfer of information, but if we consider an optical fiber
as a sensor then the other usage can be found for example in medicine or biology. If the optical fiber is heated by
sufficiently high temperature, the light signal starts to be emitted in the internal structure. This signal has a spectral
characteristic, which can be used for evaluation of temperature thanks to quality analysis. The article will describe the
evaluation of spectral characteristics for utilizationof optical fiber as fiber optic sensor for very high temperatures.
The team of authors tries to provide information on the results of the fiber-optic DTS system application under long-term
research of accumulation possibilities of thermal energy in the rock mass in this article. In 2006, was in Ostrava
implemented the largest object in the Czech Republic, which is heated by heat pump system. It is a multi-purpose aula at
VŠB-TU + CIT (Center for Information Technology). The installed heat pump system consists of ten heat pumps with a
total output of 700kW and 110 wells about 140m deep. The applied research is conducted in two measuring polygons
("Big" and "Little" polygon). Simultaneously with fiber-optic DTS system is applied group of PT1000 temperature
sensors and Geothermal Response Test (GERT). Fiber-optic DTS system is deployed inside polyethylene PE collector
via a special sensory fiber optic cable. The ecological antifreeze mixture, based on the technical spirit, used for the
collection and delivery of energy to the rock mass circulates inside of PE collector. PT1000 temperature sensors are
placed at certain intervals on the outer side of the PE U-tube within the heat well. The result of application of the fiberoptic
DTS system is information about the heat profile of wells, thermal conductivity of the geological environment and
the impact of external changes in the thermal wells, along with the accumulation possibilities of thermal energy in the
rock mass (over-summer period).
Fiber optic rings are used for synchronization of modes and optical pulses shaping in fiber lasers. The resulting pulses
are characterized by stable amplitude and reduced chirp. The length of fiber ring is chosen so as to avoid loss of laser
light coherence. New application of optical fiber loops is their inclusion in the closed loop during their excitation by laser
light modulated by low-frequency signal and middle frequency signal. If loop also includes amplifying fiber which
covers losses incurred by couplers will thus be possible evaluated a signal delay in long loop and thus measure the length
of fiber. Reverse task is possibility to measure n<sub>1eff</sub> if we know the length of SM fiber loop. This type of designed fiber
optic oscillator consists of single-mode optical fiber SM28e in lengths of order of kilometers. This fiber is connected in a
series with erbium doped fiber that covers loop losses. Loop, which acts as an oscillator is excited by DFB lasers both at
a wavelength of 1550 nm and at wavelength of 1310 nm. The paper will demonstrated the comparison between active
and passive fiber loops and their influence to accuracy of effective refractive index measurement.
Photonic fiber with single mode couplers or splitters at each fiber end can be used as a sensitive structure for fiber
sensing applications. The sensitive structure is created with two DFB lasers at λ = 1550 nm. Each laser is connected to
opposite sides of photonic fiber provided with SM couplers. One DFB laser is isolated and its light goes through variable
attenuation. Isolation is necessary for DFB laser stability. The second laser is DFB or F-P laser without any isolator. Its
radiation is driven as with driven current so with DFB laser passing through photonic fiber. Small changes of DFB laser
light passing through photonic fiber activate large changes in FP laser radiation. Temperature and pressure actuating on
photonic fiber are examples of effects that are able to change properties of passing laser light. These changes can be
measured with the help of photo detector at the second arm of SM couplers. Changes in optical spectra of F-P and DFB
laser under temperature and pressure are the results.
In those days a lot of cardiological surgeries is made every day. It is a matter of very significant importance
keeping the temperature of the hearth low during the surgery because it decides whether the cells of the muscle
will die or not. The hearth is cooled by the ice placed around the hearth muscle during the surgery and
cooling liquid is injected into the hearth also. In these days the temperature is measured only in some points of
the hearth using sensors based on the pH measurements. This article describes new method for measurement
of temperature of the hearth muscle during the cardiological surgery. We use a multimode optical fiber and
distributed temperature sensor (DTS) based on the stimulated Raman scattering in temperature measurements.
This principle allows us to measure the temperature and to determine where the temperature changes during the
surgery. Resolution in the temperature is about 0.1 degrees of Celsius. Resolution in length is about 1 meter.
The resolution in length implies that the fiber must be wound to ensure the spatial resolution about 5 by 5
The article deals with topics about fiber optic loop, evaluation of the signals delay in the loop and in case of the first
designed arrangement measurement of the fiber length. The second task is to detect the effective refractive index n1eff of
the fiber core at the given length of loop. Author's team gradually discusses how configurations for the tasks are created.
From configuration designs is possible to build up optical fiber sensor.
Paper deals with cooperation between companies and university, especially with interactions companies and students, companies and pedagogues. At present it is possible to observe insufficient level of practical skills and knowledge among students and their pedagogues, there is no articulation for companies’ demands. We try to solve this situation with the help of pilot compartment. Its main task is to associate university teachers, graduate students and companies‘ specialists. Within the scope activities of the compartment is to prepare one or two day’s long special courses. Their mass point is focused to practical training; prepare conditions for trainee-ships dedicated to teachers and students on one side and special courses for technicians, dealers and companies’ management on the other. The main goal of this compartment is an interconnection between university education and requirements out coming from praxis. There are many ways of how to fulfill such cooperation.
Optical fiber sensors are suitable for measuring almost all magnitudes these days. This
article describes one new possible area of optical fiber sensors. These sensors use for
their function fundamentals of redistribution of power inside optical fiber. This principle
should allow constructing a very sensitive optical fiber sensor.
We designed novel optical fiber that affords utilizing of optical fiber for
telecommunications and measurement at the same time. This fiber is designed to work
on two wavelengths. This fiber works on telecommunication wavelength of 1550 nm in
single mode regime and works on measurement wavelength of 850 nm in quasi-single
mode regime. The refractive index profiles of real fabricated optical fiber samples and
their development are shown in this article as well. All fiber samples were made thanks
to grant cooperation with Academy of Science of the Czech Republic.
The aim of this article is that brings new approach to utilization of optical fiber as a
sensor based on redistribution of optical power among several guided modes and to
show novel optical fiber structure design that agrees with conditions for such