Contemporary advancements in polarization fiber sensor technology offer the potential for substantial enhancements in the responsiveness of security systems, enabling their deployment even in hazardous environments. A significant advantage of these systems is their sensitivity. These fiber systems are faster and safer compared to other security sensors. The possibility of utilizing fiber sensors in environments with an explosion risk makes them irreplaceable in military facilities. This paper focuses on the analysis, design, and testing of a polarization fiber sensor in military applications. The design is focused on monitoring changes in temperature in order to detect object disturbances. Such a detector would act as a very fast, sensitive, and above all non-electrical security system. Further, the design also focuses on changes in pressure that can accompany occurrences such as the passage of military vehicles or the deflections of bridge and building structures in industrial Ex-proof dangerous areas. The amount of different arrangements and measured waveforms makes our work a unique study that confirms the universality and advantages of optical fiber polarization sensors.
The polarization of light is one of the fundamental concepts used in fiber optic sensors. Combination of polarization measurement and interferometry seems to be promising concept of future fiber optic-based sensors. We have developed a cheap and easy concept of fiber optic precise length measurement which is needed for construction of fiber ring resonators used as the light source for this combined type of sensors. This paper presents a detailed description of the measurement setup, calibration and measurement.
This paper analyzes the method of measuring optical power with an emphasis on the known methods of measuring the power of polarized light propagating through an optical fiber by two polarization axes. The method relies on monitoring the change in the behavior of the sensor fiber parameters when the temperature conditions in its surroundings change. This work deals with the possibilities of measuring the optical power for each propagation axis separately. Simultaneous measurement of the instantaneous state of polarization and a very accurate measurement of the wavelength makes it possible to obtain the necessary information about nonlinear phenomena in the optical fiber. The design of various connections that were selected for implementation in the laboratory is described in detail. The practical implementation includes a set of measurements under different conditions in which a source of temperature change was applied and the response of the parameters to these changes was monitored. The results were measured with a polarimeter and a power meter and are presented in graphs and summarized in the discussion.
The paper deals with the influence of birefringence on the change of polarization and the change of frequency in sensory optical fibers. The aim of the described research was to design and implement a set of measurements that analyze these influences. The article builds on research that has dealt with this issue in the past and offers some simplifications in the design of the measuring station, describes control measurements and analyzes in detail the response of light parameters at the sensor output to changes in temperature. The article presents, compares and discusses the results of intensity changes at individual wavelengths, which demonstrate changes not only in the instantaneous polarization state of light but also changes in wavelengths with maximum light intensity depending on temperature changes. These principles can then be used to advantage with Military, Biomedical and Physiological Sensors Systems.
The application in polarization sensor systems uses changes in the polarization of light in the optical fiber during temperature changes. The principle of operation consists in the specific propagation of polarized light by special optical fibers, which, thanks to their construction, keep the light in two axes, but change the speed of their propagation and thus the instantaneous state of light polarization. It has been shown that by suitable methods it is possible to transform changes in the polarization of light into changes in its intensity, which can be detected very efficiently and quickly by a photodiode. This method has been practically verified, implemented by fiber components and confirmed as suitable for the implementation of a fiber sensor of thermal field disturbance. However, it turns out that especially in military and biomedical applications it is impossible to place a source of optical radiation close to the measured subject and the sensor must be powered remotely using optical fibers of the order of kilometers. This paper shows the possibility of using long optical paths to power the polarization sensor.
The article deals with the exact measurement of wavelength intensities in the vicinity of the frequency of the light source at the output of the polarizing optic fiber sensor. A functional polarizing fiber optic temperature sensor is used as the measuring element, and the frequency variations are induced by a birefringence change in the fiber retaining polarization due to temperature changes. Different speed of light propagation in the two polarization planes of the polarization maintaining optical fiber was used to excite the birefringence. Highly detailed measurements show that the intensity peaks vary depending on the changing temperature of the optical fiber due to the changing birefringence. Thanks to accurate measuring instruments, the dependence between the instantaneous change in the polarization state and the change in the maximum intensity at given wavelengths were observed. The described measurement determines whether wavelength variations may be a suitable alternative to evaluating polarization changes, which in some situations is difficult and costly.
Applications in sensor systems utilize, for example, changes in the polarization of light in an optical fibre during temperature changes. The principle of operation is based on the specific propagation of polarized light by special optical fibres, which, due to their construction, keep the light in two axes, but the speed of their propagation and thus the instantaneous state of polarization of light change. It has been shown that by suitable methods it is possible to transform changes in light polarization into changes in light intensity, which can be detected very effectively by a photodiode. This method has been practically verified, implemented by fibre components and confirmed to be suitable for implementing a fibre sensor of thermal field disruption. The aim of this work is to point out the current possibilities of using polarized light in sensor technology. This polarization system can efficiently secure areas, the surrounding environment and monitor the changes that occur.
The accurate measurement of temperature changes is the key skill not only for predictions of various natural phenomena or to detect intrusion of the object. The temperature changes we nowadays measure in local climate zones or Urban Heat Islands. The environmental quality is an essential feature of life quality and to improve it serve many remote sensing-based urban planning indicators, which are the common part of present smart cities.
Continuously developing fibre optic sensors allow their benefits to be exploited in more and more applications. Defensive Perimeter Detection by Polarization Change of the Fiber Optic Signal offers an effective possibility to detect quickly and in time disturbing a predefined space. This detection system uses the polarizing properties of light and, in particular, the birefringence of optical fibres. The disclosed detection system focuses on temperature changes that may be caused by external or internal disruption of the site. The main detection equipment is the polarization maintaining optical fibre with the same excitation in both polarization axes. The transmission rate in both axes is in the ideal case the same, but due to birefringence, inhomogeneity, and imperfection of production and next causes the mutual delay of both signals causes the signal polarization state change or even the series of polarization states changes, which can be observed in laboratory conditions and described by known mathematical methods. However, these changes can be transformed by linear polarizer to the intensity changes. This conversion allows the changes significantly easier to evaluate.
The paper deals with the analytical description of the sensitivity and dynamic characteristics of the birefringent fiber temperature response usable for realization of thermal field disturbance sensors. The response is given by changing the phase shift development between two polarization modes in birefringent fiber, caused by body heat transfer of different temperatures. The aim is to analyze sensitivity and dynamic behaviors, which are significant when optical fiber is used as a sensor of temperature field disturbance. The result shows a very good match with measured time responses, especially due to a specific arrangement for suppressing the influence of conduction and convection.
Due to increasing demands for bandwidth are nowadays very popular optical networks. Installation of new fiber-optic networks is expensive, so is necessary to use existing fiber optic network very effectively. The main parameters that limit the optical networks are dispersion and attenuation. Efficiency optical networks could improve the use of two polarization axes, similar to the technology used in radio technologies. Use of fiber preserves polarization allows the use of two polarization planes. This article deals with the optical wavelength division multiplex in the polarization maintaining fibers.
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