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We have manufactured and characterized a birefringent holey fiber of a new construction. The birefringence in this fiber is induced by the highly elliptical shape of the core, which consists of a triple defect in a hexagonal structure. Using a hybrid edge-nodal finite-element method, we calculated the spectral dependence of phase and group modal birefringence for spatial modes E11 and E21 in idealized and in real fiber, whose geometry we determined by using a scanning-electron microscope. Results of our calculations show that technological imperfections significantly affect the fiber's birefringence. Normalized cutoff wavelengths for higher-order modes relative to the filling factor were also determined for the idealized structure. We observed a significant disagreement between theoretical and experimental values of cutoff wavelengths, which was attributed to high confinement losses near the cutoff condition. We also measured the spectral dependence of the phase and the group modal birefringence for spatial modes E11 and E21. The measured parameters showed good agreement with the results of modeling.

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We report on experimental studies of polarimetric sensitivity to hydrostatic pressure and temperature in two highly birefringent index guided photonic crystal fibers, in which birefringence is induced by one row of the cladding holes with diameters smaller than the other cladding holes. The sensitivity measurements were carried out in the spectral range from 0.6 µm to 1.6 µm. Our results show that absolute value of the polarimetric sensitivity to hydrostatic pressure can reach 23 rad/MPa×m, which is almost one order of magnitude higher than in conventional fibers with elliptical core. Simultaneously, polarimetric sensitivity to temperature is at least two orders of magnitude lower than in conventional highly birefringent fibers. Moreover, we proved experimentally that one of the investigated fibers is completely insensitive to temperature at certain wavelength.

We measured spectral dependence of the polarimetric sensitivity to temperature in three birefringent holey fibres with different geometries. Our results show that thermal properties of the birefringent photonic crystal fibres depend very much on the air hole arrangement. Using the procedure which allows us to determine the sign of temperature sensitivity, we demonstrated that one of the investigated fibres is insensitive to temperature at a certain wavelength. We also measured the temperature sensitivities for the fibres with and without polymer coating and showed that the coating changes significantly the fibre response to temperature. Furthermore, we demonstrated experimentally that the spectral dependence of the polarimetric sensitivity to temperature in birefringent holey fibres obeys a scaling law.

Employing several interferometric methods, we measured in a broad spectral range the wavelength dependences of the phase modal birefringence and the polarization mode dispersion for the LP01 and even LP11 spatial modes supported by a birefringent holey fibre. We also determined the wavelength dependence of the intermodal dispersion between the X- and Y-polarized LP01 and even LP11 spatial modes. Furthermore, using a full-vector finite-element method, we modelled all the measured dispersion characteristics and demonstrated good agreement between experimental and theoretical results.

Fast, frequent, accurate and reliable measurements of strain, vibration, and displacement, as well as organic physical quantities such as temperature, stress or strain are elements such as moisture and ice. In addition, because the known to be of utmost importance in areas such as process temperature and strain states of FBGs directly affect their industry or structural health monitoring. Photonic crystal fibres reflectivity spectrum, they can provide structural engineers (PCF) [1] constitute a class of optical fibres that has a large with measurements not previously possible, including potential for a number of novel applications in the sensing detecting changes in stress in buildings, bridges, and airplane domain. The manufacturing flexibility of PCF allows fabricating different types of specialty microstructured fibres including fbodies; deoth measurements n streams, rvers, andsreservoirs endlessly single mode, double clad, germanium or rare earth for flood control; and temperature and pressure measurements doped, highly birefringent, and many other fibres with in deep oil wells. They also offer excellent resolution and particular features. In this paper we analyse several of these and range, absolute measurements and modest cost per channel. describe how they can be exploited for sensing applications. We Furthermore, because FBG sensors are passive, they can be pay particular attention to temperature and hydrostatic either time-or wavelength-multiplexed, which allows for pressure sensitivities. We also report on new microstructure distributed sensing -a key advantage for structural health geometries dedicated to sensing applications and on Bragg monitoring [2]. gratings written in highly birefringent photonic crystal fibre.The majority of sensors mentioned above rely on conventional glass optical fibres. A new class of microstructured fibres (MSFs) or photonic crystal fibres (PCFs), also called holey fibres, became in recent years a I. INTRODUCTION subject of extensive research. It has already been demonstrated that MSFs can be used in numerous Opticl fe sapplications such as compensation of chromatic dispersion, Optical fibrese networksa provingsh abit generation of supercontinuum or improvement in efficiency monitor bridges, buildings, oil rigs, power lines, dams, of fibre-optic lasers. Polarization properties of MSFs are also tunnels and even hillsides. These sensors for a monit very interesting. For example, it has been shown that modal stress and itS evolution over time, or following a catastrophic birefringence in MSFs may exceed 10-3, which is one order event such as an earthquake or flood. As such they can o generate alerts when structural safety is affected. Optical fibre [3]-[10] d sensors can also play a key role in homeland security as they can provide a broader coverage and possibly a better accuracy inrphotoni stalesT ftiXgpolarizing compare to exstn moiorn mehd.i photonic crystal fibres. The first index guided polarizing compared topulexfistn moniorin meietos. onafibreBragggrating holey fi...