DOI: 10.17586/2226-1494-2015-15-6-1015-1020


M. E. Efimov, M. Y. Plotnikov, M. V. Mekhrengin, V. S. Lavrov

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For citation: Efimov M.E., Plotnikov M.Yu., Mekhrengin M.V., Lavrov V.S. Directivity pattern investigation of dual fiber optic hydrophone. Scientific and Technical Journal of Information Technologies, Mechanics and Optics, 2015, vol. 16, no. 6, pp. 1015–1020.

Subject of Research. The paper provides comparison of theoretical and experimental research results of directivity pattern of dual fiber optic hydrophone at various acoustic frequencies. Application of multiple fiber optic transducers in fiber optic hydrophone design placed in sensitive arm of the interferometer gives the possibility for increasing the sensitivity of a fiber optic hydrophone without changing the fiber-optic transducers. In the simplest case, such fiber optic hydrophone can be built on the basis of two spatially separated acoustic transducers. However, this diversity inevitably leads to the directivity pattern unevenness of the fiber optic hydrophone at acoustic frequencies which wavelengths are commensurate with the size of the transducers system. Method. Mathematical model has been created and it became the base material for a theoretical study of two acoustic transducers system in Mathcad environment. Directivity pattern was described by a mathematical formula, depending on the frequency of the acoustic impact and the distance between sensors. To confirm the correctness of theoretical research of the directivity pattern, dual fiber optic hydrophone on Bragg gratings was produced and investigated experimentally. It consists of two consequently welded sensitive elements with a 9 cm distance between them. In trials carried out in open water conditions, fiber-optic hydrophone was placed on the rotator and rotated relative to the piezoceramic emitter for 360 degrees. During investigation, the signal from a fiber optic hydrophone has been recorded simultaneously with the rotation. Further, after the data processing in MATLAB, amplitude of the measured phase signal and the directivity pattern of the test sample were estimated. Amplitude estimation of the measured phase signal and directivity pattern creation of the sample was performed at frequencies equal to 1000, 3000 and 8000 Hz. Main Results. Sensitivity of the dual fiber optic hydrophone is 5.5 rad/Pa at the frequency of 1 kHz, 0.77 rad/Pa at the frequency of 3 kHz and 0.42 rad/Pa at the frequency of 8 kHz. Comparison of the calculated values and experimental results has confirmed the correctness of the proposed model. Possibility of increasing sensitivity of fiber optic hydrophone is shown with the use of multiple transducers without changing its directivity pattern at frequencies up to 3 kHz. At frequencies above 3 kHz dual fiber optic hydrophone with proposed design acquires expressed directivity properties. Practical Relevance. The results can be applied in the design of fiber optic hydrophones in new generation of geophysical equipment, combining compactness and high sensitivity.

Keywords: fiber-optic hydrophone, modeling, directivity pattern.


1. Efimov M.E., Plotnikov M.Yu., Kulikov A.V. Modeling and experimental study of a fiber optic hydrophone sensing element. Scientific and Technical Journal of Information Technologies, Mechanics and Optics, 2014, no. 4 (93), pp. 158–163. (In Russian)
2. Efimov M.E., Plotnikov M.Yu., Kulikov A.V. Modelirovanie i issledovanie chuvstvitel'nogo elementa volokonno-opticheskogo gidrofona [Modeling and studying of a fiber optic hydrophone sensing element.]. Sbornik Tezisov Dokladov Kongressa Molodykh Uchenykh, Vypusk 4 [Proc. Congress of Young Scientists, no. 4]. St. Petersburg, ITMO University Publ., 2014, pp. 365–366.
3. Liokumovich L.B. Polyarizatsionnye Effekty v Volokonnykh Interferometrakh na Osnove Dvulucheprelomlyayushchikh Svetovodov. Avtoref. diss. … d-ra fiz.-mat. nauk [Polarization Effects in Optical Interferometers Based on Birefringent Fibers. PhD Theses Phys.-Math. Sci.]. St. Petersburg, 2008, 32 p.
4. Sverdlin G.M. Gidroakusticheskie Preobrazovateli i Antenny [Sonar Transmitters and Antennas]. Leningrad, Sudostroenie Publ., 1988, 200 p.
5. Guo K., Zhang M., Liao Y., Lai S., Wang Z., Tang J. Fiber-optic hydrophone with increased sensitivity. Proceedings of SPIE – The International Society for Optical Engineering, 2006, vol. 6293, art. 629312.
6. Fiber Optic Hydrophones. Stockbridge, 2011, 5 p.
7. Cox B.T., Zhang E.Z., Laufer J.G., Beard P.C. Fabry Perot polymer film fibre-optic hydrophones and arrays for ultrasound field characterization. Journal of Physics: Conference Series, 2004, vol. 1, pp. 32–37. doi: 10.1088/1742-6596/1/1/009
8. Plotnikov M.Yu. Volokonno-Opticheskii Gidrofon. Avtoref. dis. kand. tekhn. nauk. [Fiber-Optic Hydrophone. Thesis Eng. Sci. Diss.]. St. Petersburg, NRU ITMO Publ., 2014, 23 p.
9. Doyle С. Fiber Bragg Grating Sensors. An Introduction to Bragg gratings and interrogation techniques. Smart Fibres Ltd., 2003. Available at: (accessed 19.07.2015).
10. Zhou Z., Graver T.W., Hsu L., Ou J. Techniques of advanced FBG sensors: fabrication, demodulation, encapsulation and the structural health monitoring of bridges. Pacific Science Review, 2003, vol. 5, pp. 116–121.
11. Aksarin S.M., Arkhipov S.V., Varzhel S.V., Kulikov A.V., Strigalev V.E. Dependence investigation of the anisotropic single-mode fiber parameters on a winding diameter. Scientific and Technical Journal of Information Technologies, Mechanics and Optics, 2013, no. 6 (88), pp. 22–26. (In Russian)
12. Jameson P., Burton T., Ordubadi A., Africk S. Design of rubber mandrel fiber optic hydrophones. Journal of Acoustical Society of America, 1981, vol. 70, pp. 100. doi: 10.1121/1.2018646
13. Lurton X. An Introduction to Underwater Acoustics. Principles and Applications. 2nd ed. Springer, 2002, 724 p.
14. Hovem J.M. Underwater acoustics: propagation, devices and systems. Journal of Electroceramics, 2007, vol. 19, no. 4, pp. 339–347. doi: 10.1007/s10832-007-9059-9
15. Urick R.J. Principles of Underwater Sound. 3rd ed. NY, McGraw-Hill, 1983, 423 p.

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