6-14

UDC 621.396
DOI: 10.15350/2306-2819.2017.4.6

EQUIVALENCY AND MAPPING METHODS IN THE TASK
OF THE INTERPRETATION OF MATERIAL FREQUENCY DISPERSION EFFECTS
IN OPTICAL FIBER

D. V. Ivanov¹, V. A. Ivanov¹, M. I. Ryabova², E. V. Katkov¹
¹Volga State University of Technology,
3, Lenin Square, Yoshkar-Ola, 424000, Russian Federation
E-mail: IvanovVA@volgatech.net
²Bauman Moscow State Technical University,
5-1, 2-ya Baumanskaya Street, Moscow, 105005, Russian Federation
E-mail: miryabova@mail.ru

ABSTRACT

Introduction. At present fiber-optics communication becomes an increasingly popular method of the data transfer and it replaces other types of wire communication due to its unique characteristics (advantages). However if the information rate increases considerably, material dispersion has a significant impact on signal propagation. Material dispersion leads to light pulse broadening. It is caused by the dependence of phase wave velocity on its frequency. Thus, phase dispersion in fiber leads to space division of the light pulse into components, which move with the different rate and accordingly, they have a different group delay (different colors). In other words, the carrier frequency acquires dependence on time (chirping). The effect of the decomposition from the red to blue color received the name normal (positive) dispersion in optics because the rate of low-frequency components (red) is higher than the rate of high-frequency components (blue). Color decomposition in a different order is customarily referred to as abnormal (negative) dispersion. The purpose of the work is the research on the effects of the material dispersion of a fiber-optic communication line as the linear one-dimensional system, characterized by frequency, dispersion and impulse functions. To achieve this purpose, the method of the transformation of the frequency characteristic into the impulse response using the dispersion system characteristic has been developed. Practical significance. Special attention was given to a particular case, when the dispersion characteristic has horizontal sections, in the neighborhood of which there is no nonlinear phase dispersion. In this frequency range, the condition of steady light pulse propagation is fulfilled, when a signal can be transmitted over a considerable distance without distortion. In optics this case is physically implemented in the medium with abnormal distortion, when because of a nonlinear effect on the optical medium by the high-power light pulse, the refractive index in the corresponding frequency range increases and the additive effect of nonlinearity and dispersion leads to the horizontality of the dispersion system characteristic. Results. The interpretation of the effects of normal and abnormal phase frequency dispersion of the second order, when the dispersion characteristic increases or decreases linearly, is presented. The effects of normal and abnormal phase frequency dispersion of the third order have been studied using the piecewise-linear approximation of the dispersion characteristic. Besides, based on the represented model, the effect of the collapse of solitons due to their interaction with low delay between them has been considered.

KEYWORDS

optical fiber; material dispersion; chirp-modulation; soliton regime; soliton collapse

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ACKNOWLEDGMENT

The work was carried out with the grants support from the Russian Foundation for Basic Research: № 16-37-60068, 16-07-00210, 17-07-01590.

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For citation: Ivanov D. V., Ivanov V. A., Ryabova M. I., Katkov E. V. Equivalency and Mapping Methods in the Task of the Interpretation of Material Frequency Dispersion Effects in Optical Fiber. Vestnik of Volga State University of Technology. Ser.: Radio Engineering and Infocommunication Systems. 2017. No 4 (36). Pp. 6-14. DOI: 10.15350/2306-2819.2017.4.6