Gabriela Statkiewicz-Barabach

Highly birefringent microstructured fibers with enhanced sensitivity to hydrostatic pressure

We designed, manufactured and characterized two birefringent microstructured fibers that feature a 5-fold increase in polarimetric sensitivity to hydrostatic pressure compared to the earlier reported values for microstructured fibers. We demonstrate a good agreement between the finite element simulations and the experimental values for the polarimetric sensitivity to pressure and to temperature. The sensitivity to hydrostatic pressure has a negative sign and exceeds -43 rad/MPa x m at 1.55 microm for both fibers. In combination with the very low sensitivity to temperature, this makes our fibers the candidates of choice for the development of microstructured fiber based hydrostatic pressure measurement systems.

Simultaneous measurement of multiparameters using a Sagnac interferometer with polarization maintaining side-hole fiber

A Sagnac interferometer with a section of a polarization maintaining side-hole fiber for multiparameter measurement is proposed. The sensor was experimentally demonstrated to be sensitive to torsion, temperature, and longitudinal strain, simultaneously. The birefringence in the investigated side-hole fiber is induced simultaneously by the elliptical shape of a germanium-doped core and by field overlap with the air holes surrounding the core. The latter effect is purely geometrical and causes high chromatic dispersion of the group birefringence in the long wavelength range, which results in a different period of spectral interference fringes. A different wavelength response is obtained for each interference fringe peak when the fiber is subjected to torsion, temperature, or longitudinal strain. A matrix equation for simultaneous measurement of the three parameters--torsion, temperature, and longitudinal strain--is also proposed.

Sensing characteristics of rocking filter fabricated in microstructured birefringent fiber using fusion arc splicer

We demonstrate that higher order rocking filters coupling energy between polarization modes at several wavelengths can be fabricated in a birefringent photonic crystal fiber using a fusion arc splicer. Three resonant couplings were identified, respectively at 855, 1271, and 1623 nm for the filter with a pitch distance of 8 mm characterized in this work. We also measured the filter response to temperature, elongation and hydrostatic pressure at the first and the second resonance. Our results show that the fabricated filter has very low sensitivity to temperature 1.77 and 1.38 pm/K, moderate sensitivity to elongation 1.35 and 1.12 nm/mstrain, and extremely high sensitivity to hydrostatic pressure 6.14 and 3.30 nm/MPa, respectively at the first and the second resonance.

How to strengthen or weaken the HRV dependence on heart rate — Description of the method and its perspectives

a Department of Cardiology, Regional Medical Center, Opole, Poland b Institute of Physics, Wroclaw University of Technology, Wroclaw, Poland c Instytut Fizyki imienia Mariana Smoluchowskiego and Mark Kac Complex Systems Research Center, Uniwersytet Jagiellonski, ulica Reymonta 4, PL-30-059 Krakow, Poland d 1. Medizinische Klinik und Deutsches Herzzentrum München der Technischen Universität München, Munich, Germany e Department of Cardiology-Intensive Therapy, University School of Medicine, Poznan, Poland f Institute of Physics, University of Zielona Gora, Zielona Gora, Poland

Fabrication of multiple Bragg gratings in microstructured polymer fibers using a phase mask with several diffraction orders

We demonstrate for the first time a possibility of fabrication of Bragg gratings in polymer microstructured fibers with multiple reflection peaks by using He-Cd laser (λ = 325 nm) and a phase mask with higher diffraction orders. We experimentally studied the growth dynamics of the grating with the primary Bragg peak at λ(B) = 1555 nm, for which we also observed good quality peaks located at λ(B)/2 = 782 nm and 2λ(B)/3 = 1040 nm. Temperature response of all the Bragg peaks was also investigated. Detailed numerical simulations of the interference pattern produced by the phase mask suggests that the higher order Bragg peaks originate from interference of UV beams diffracted in ± 1st, ± 2nd orders. We also demonstrated the grating with the reflection peak at λ(B)/2 = 659 nm, which is the shortest Bragg wavelength ever reported for polymer microstructured fibers. This peak was observed for the grating with primary Bragg wavelength at λ(B) = 1309 nm.

Control Over the Pressure Sensitivity of Bragg Grating-Based Sensors in Highly Birefringent Microstructured Optical Fibers

We present fiber Bragg grating (FBG)-based hydrostatic pressure sensing with highly birefringent microstructured optical fibers. Since small deformations of the microstructure can have a large influence on the material birefringence and pressure sensitivity of the fiber, we have evaluated two microstructured fibers that were made from comparable fiber preforms, but fabricated using different temperature and pressure conditions. The magnitude and sign of the pressure sensitivity are found to be different for both fibers. We have simulated the corresponding change of the Bragg peak separation with finite-element models and experimentally verified our results. We achieve very high experimental sensitivities of -15 and 33 pm/MPa for both sensors. To our knowledge, these are the highest sensitivities ever reported for birefringent FBG-based hydrostatic pressure sensing.

Measurements of stress-optic coefficient in polymer optical fibers

We have systematically measured the differential stress-optic coefficient, DeltaC, in a number of poly(methyl methacrylate) (PMMA) fibers drawn with different stress, ranging from 2 up to 27 MPa. DeltaC was determined in transverse illumination by measuring the dependence of birefringence on additional axial stress applied to the fiber. Our results show that DeltaC in PMMA fibers has a negative sign and ranges from -4.5 to -4.5x10(-12) Pa(-1), depending on the drawing stress. Increase of the drawing stress results in greater initial fiber birefringence and lower DeltaC.

Highly birefringent dual-mode microstructured fiber with enhanced polarimetric strain sensitivity of the second order mode

We present the results of theoretical and experimental characterization of a designed and manufactured dual-mode highly birefringent microstructured fiber. We also demonstrate the measured values of polarimetric temperature and strain sensitivity of both the fundamental and second order modes. As the mode field of the second order mode has a strong interaction with the fiber air holes, we observed a significant (over two orders of magnitude) increase in the polarimetric strain sensitivity of this mode in comparison to the fundamental mode. The enhanced strain sensitivity together with the low temperature sensitivity makes our fiber very attractive for application as extremely sensitive temperature independent strain transducers.

How to select patients who will not benefit from ICD therapy by using heart rate and its variability

How to select patients who will not benefit from ICD therapy by using heart rate and its variability? Jerzy Sacha ⁎, Szymon Barabach , Gabriela Statkiewicz-Barabach , Krzysztof Sacha , Alexander Muller , Jaroslaw Piskorski , Petra Barthel , Georg Schmidt d,1 a Department of Cardiology, Regional Medical Center, Opole, Poland b Institute of Physics, Wroclaw University of Technology, Wroclaw, Poland c Instytut Fizyki imienia Mariana Smoluchowskiego and Mark Kac Complex Systems Research Center, Uniwersytet Jagiellonski, ulica Reymonta 4, PL-30-059 Krakow, Poland d 1. Medizinische Klinik und Deutsches Herzzentrum Munchen der Technischen Universitat Munchen, Munich, Germany e Department of Cardiology-Intensive Therapy, University School of Medicine, Poznan, Poland f Institute of Physics, University of Zielona Gora, Zielona Gora, Poland

Hydrostatic Pressure and Strain Sensitivity of Long Period Grating Fabricated in Polymer Microstructured Fiber

We report on sensing characteristics of a long period grating fabricated in polymer microstructured fiber using transverse periodic loading combined with fiber heating. The grating is characterized for strain and hydrostatic pressure sensitivity and shows linear response to both parameters with sensitivity coefficients equal, respectively, -1.39 nm/mstrain and 2.29 nm/MPa. We also measure the variation of the resonance depth induced by both parameters and study the temperature response of the grating.