V A Konyshev

A simple method of measuring the effective SRS coefficient in single-mode optical fibres and its applicability limits

This paper describes techniques for measuring the SRS coefficient in a wide spectral range, including the region of small Stokes shifts. A simple, approximate method is proposed for evaluating the SRS coefficient near a gain peak. Spectral dependences of the SRS coefficient are presented for various telecom fibres.

Experimental study and numerical modelling of a 3 × 100G DP-QPSK superchannel

Crosstalk effects are studied experimentally in a DWDM line with 100G DP-QPSK channels at a frequency convergence of the channels (three channels with a frequency separation of 50, 37.5 and 33 GHz) in the C-band. Spans of 100 km in length are used, with the number of spans varying from one to six. The required optical signal-to-noise ratio (OSNRR) is determined experimentally for a different number of spans, interchannel intervals and input power. We propose a theoretical model based on the numerical modelling that describes the influence of adjacent channels at a strong convergence. The model is calibrated using the obtained experimental data. Based on the proposed model, we calculate the maximal value of the spectral efficiency in systems with a dense arrangement of 100G DP-QPSK channels (~3.2 bit s−1 Hz−1).

Nonlinear distortions as nonlinear noise in coherent fibre-optic communication lines

A phenomenological model describing nonlinear distortions in coherent fibre-optic communication lines is investigated. This model makes it possible to extend the range of application of the nonlinear noise model as compared with the well-known GN model. A method for experimental determination of the main parameters of the proposed model is described, and the sources of possible errors are discussed.

Design of high-bit-rate coherent communication links

We report an analysis of the problems encountered in the design of modern high-bit-rate coherent communication links. A phenomenological communication link model is described, which is suitable for solving applied tasks of the network design with nonlinear effects taken into account. We propose an engineering approach to the design that is based on the use of fundamental nonlinearity coefficients calculated in advance for the experimental configurations of communication links. An experimental method is presented for calculating the nonlinearity coefficient of communication links. It is shown that the proposed approach allows one to successfully meet the challenges in designing communication networks.

Optical signal quality improvement due to nonlinear interaction between spectral channels

This paper examines stimulated Brillouin scattering (SBS) suppression in multichannel DWDM systems owing to nonlinear cross interaction between the channels and its effect on optical signal quality in a communication link. We present an experimental study of single-, three- and five-channel systems with NRZ channels. The optical signal quality in the three- and five-channel systems is shown to be better than that in the single-channel system. The reason for this is that cross-phase modulation broadens the spectrum of the signal and raises the SBS threshold. This in turn ensures a more pronounced optical signal quality improvement due to self-phase modulation.