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The team of authors was concerned in the development and construction of low-cost free space optical link and simulations of the influence of atmospheric conditions on this link. The article contains description of electronic design and attention is also dedicated to simulations of atmospheric conditions. Gradually, the most frequently occurring atmospheric conditions and their impact on the available bit rates were tested. An integral part of the article is calculation of the energy balance of the whole link. At the end are shown images of the measured eye diagrams and samples of measured distribution of optical power using a digital camera and its processing in MATLAB.

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 n1effif 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.

Microstructured polymer optical fibers represent quite new technology that is still in the research and development stage. However, some advances and possible applications are available even now. One of these is the possibility of filling the fibers with various fluids to enhance or modify some of their characteristics. Filling fibers with fluorescent dyes is a good method to describe how the filled fiber behaves and to demonstrate sensing applications.

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.