Filip Dvorak

Response analysis of thermal field disturbance sensor

This paper continues previous research work dealing with the study of sensor of thermal field disturbance. The utilization of polarization maintaining fiber (PMF) birefringence high sensitivity upon the temperature is taken in advantage. The effect of laser source wavelength and optical fiber beat length upon the fiber response invoked by disturbing temperature field is theoretically analyzed. The sensitivity of optical fiber response upon the temperature disturbing is experimentally verified. The optical fibers for wavelength 633 nm and 1550 nm with its beat length 2 mm and 5 mm are used in experiment. The experimental work was conducted for different lengths of disturbing temperature radiation sources from fiber-optic sensor and for different length of sensor exposed to the radiation. The relation of fiber response for the wavelength of 633 nm upon different magnitude of disturbing temperature radiation was also investigated. The particular results of experimental work are presented in this paper. The construction of sensor system with desired sensitivity and selection of its parameters can be done based on the obtained results.

Optical fibers with high birefringence as a sensor element

The polarization maintaining fiber (PMF) sensitivity during excitation of both polarization modes is the principle of this sensor function. This excitation is caused by temperature change and by absorbing of thermal radiation. This mechanism is used for detection of temperature field disturbance as an indicator. This article describes experimental tests to determine PM fibers Panda style responses made by applying of thermal source with different initial temperature. The aim of this study was to determine the sensitivity of PMF to radiating heat, to upgrade the space configuration and time response.

Measurement of polarization properties of laser diodes

The paper deals with investigation of polarization in different types of laser diodes which can be used as sources of optical radiation for atmospheric optical communication systems. Results of laser beams study for different types of laser diodes and typical wavelengths are presented in the paper. Also possibility of laser beam transformation, from the type of polarization point of view, was studied as idea for improvement the immunity of laser beam towards the atmosphere conditions, mainly turbulence. Polarization properties of laser diodes were presented in the form of polar intensity diagrams and Stokes vectors represented on the Poincaré sphere.

Subarray incoherency compensation for DOA estimation of 8-element antenna array

MUSIC algorithm is one of the most widely known and used signal source estimation techniques. A presented paper deal with an experiment of direction of arrival (DOA) estimation of signal sources using two subarrays without coherency or with rough synchronization. The performance of DOA estimation improves with increasing the number of elements of antenna array. In this case, a practical measurement is performed using 8-element antenna array (each antenna subarray includes 4-element), received signals between two antenna subarrays are roughly synchronized. For estimation DOA signals we proposed an algorithm to estimate DOA signal using MUSIC algorithm with higher accuracy. Results show that the algorithm could estimate DOA signals correctly in the case of two incoming coherent signals.

Study of temperature turbulences effect towards linearly polarized optical beam propagating in atmospheric environment

The paper deals with study of temperature turbulences effect towards the optical beam. The horizontally and vertically polarized optical beams have been studied. The turbulence flux has the vertical direction and the optical beam is propagating through the atmosphere environment with three different states of turbulences. The evaluation of obtained data was done by means of relative variance of optical intensity and refractive index structure parameter computing. The different temperature turbulences rate of effect towards the horizontally and vertically polarized beam has been found.