Andis Supe

Comparison of reliability of ADSS cables mounted on different voltage electric power lines

In this paper authors provide the results from the research about all-dielectric self-supporting optical cables reliability when these cables are mounted on the rests of high voltage electrical power lines. Comparison of reliability parameters is given between optical cable lines mounted on the power lines up to 110kV and 330kV. Additionally measurement results of fiber polarization mode dispersion and maximum tensile load are given for different all-dielectric self-supporting cables.

Minimization of FWM effect in nonlinear optical fiber using variable channel spacing technique

Optical Fiber Communication widely implements Dense Wave Division Multiplexing (DWDM) technique in order to accommodate large number of channels within a limited bandwidth. But, this technology suffers a serious degradation in signal quality due to inter-channel interference. Optical Kerr Effect, in addition to this, worsens the situation. This paper deals with minimization of Four Wave Mixing (FWM) impact, one of the Optical Kerr effects, by using variable channel spacing instead of conventional fixed channel spacing technique. FWM effect generates spurious components at multiple frequencies, whose effective amplitude can be reduced using different channel spacing. Bit Error Rate (BER) observed for different length of fiber has been analyzed with an aim to estimate the difference between variable channel spacing algorithms. Obtained results have shown that BER of 10–11 can be reached with 153.7 km long fiber for fixed channel spacing while the usage of variable channel spacing method keeps the same BER level with 160.5 km long fiber.

Demonstration of binary PolSK to OOK modulation format conversion using a single-pump fiber optical parametric amplifier

The main goal of this paper is to investigate the ability of a single-pump fiber optical parametric amplifier with linearly polarized pumping radiation to provide binary polarization shift keying to intensity on-off keying modulation format conversion in a single channel optical transmission system. The amplifier produced up to 14.8 dB of on-off gain, and it was demonstrated that such level of amplification is sufficient to provide modulation format conversion, while maintaining acceptable quality of the converted signal. It was found that due to fiber birefringence the original state of polarization needs to be recovered at the input of the amplifier, otherwise, drop in amplification and converted signal discrepancies will occur.

Evaluation of effective area and nonlinearity coefficient of erbium-ytterbium doped optical fibers

In present research, Aeff parameter measurements for ytterbium (Yb3+) and erbium (Er3+) doped optical fibers were performed experimentally by the usage of transverse shift measurement method. All the measurements were done at two different wavelengths (1310nm and 1550nm accordingly) at various power levels with an aim to evaluate how effective area depends on those parameters. With the increase of a step size the higher peak of power values for Erbium fiber are distributed in range of -30dBm while for Ytterbium doped fibers around -20 dBm. Obtained results have been analyzed and compared with an aim to estimate the characteristics for both doped fiber types.

Different optical fiber nonlinear coefficient experimental measurements

In this paper, nonlinear nature of three different optical fibers: Corning SMF-28 ultra optical fiber, Draka enhanced single-mode optical fiber and highly nonlinear fiber has been studied experimentally by the measurement of nonlinear coefficient using four wave mixing process. Obtained results have shown that measured values of the nonlinear coefficient are 0.78 W^-1km^-1 for SMF-28 fibers, 1.45 W^-1km^-1 for enhanced singlemode fiber and 10.68 W^-1km^-1 for highly nonlinear fiber, that conforms to typical values.

Polarization Effects on the Non-Linearity of a Highly Non-Linear Fiber

Abstract The effective non-linear parameter of a highly non-linear optical fiber was measured using the four-wave mixing effect. A value of γ = 10.6 W–1/km was obtained for a small wavelength separation between pump and signal waves, whereas for a large wavelength separation, a value of = 8γ/9 = 9.4 W–1/km was found. This value corresponds to an average of the Kerr non-linearity over the Poincaré sphere, since the polarization of both the pump and signal waves become uncorrelated in the last case. A theoretical model is proposed to describe the variation of the effective non-linear parameter with the wavelength separation between pump and signal waves, which is in good agreement with the experimental data.

Pump and filtering optimization in Mamyshev regenerator

In this paper we present results from the study of optical signal regeneration using Mamyshev type regenerator. We have performed the simulations and experimental characterization of regenerator by obtaining it`s transfer function and output optical signal to noise ratio measurements for two different filters - fixed and a tunable optical filter. Investigated regenerator setup consists of a high power erbium doped fiber amplifier, highly nonlinear fiber and a single stage optical filtering. Signal used for regeneration was an on-off keying return to zero code 40 Gbps pulse sequence. To find out optimum filter pass-band shift from signal`s central wavelength the regenerator`s transfer function was measured. Results show that highest output signal to noise ratio improvement for the fixed filter is at 0.6nm shift and amplifier output power set to 63 mW. While the tunable filter shift is 0.7nm at the 100 mW power level.

Experimental characterization of a highlly nonlinear fiber

In this paper we present an experimental characterization of a highly nonlinear silica fiber. It includes the determination of the fiber effective nonlinear parameter using the nonlinear four-wave mixing process. From the experimental results, a value γ = 10.6 W−1 km−1 has been obtained for the nonlinear parameter in the co-polarized case, which was reduced to γ = 9.4 W−1 km−1 in the case of a decorrelated state of polarization between pump and signal waves. A threshold power of 17.8mW was found for the stimulated Brillouin scattering process. A Raman gain curve extending over a frequency range of 25 THz, with a peak value shifted by 13.1 THz from the pump frequency, was also measured.

Research of optical radiation intensity in erbium doped optical fibers

Optical amplifier usage in the fiber optics transamission systems significantly improves the transmission distance. But it also influence the signal quality. This article describes a study on optical intensity characteristics and its impact to optical signal propagation in the erbium doped fiber (EDF) used in the doped fiber amplifiers. First of all the far field optical power distribution measurements are performed at the output of Er3+ doped fiber using transverse shift measurement method. Based on the experimental results, the fiber effective area Aeff has been calculated. Following from the effective area results comparative analysis and estimation of the optical intensity results is given for EDF at different wavelengths. It was found that in the wavelength range of 1465-1575nm optical intensity changes from 66.94kW/cm2 at λ=1575nm to 70.18kW/cm2 at λ=1470nm. But the nonlinear refractive index change in the erbium doped amplifier amplification range is found to be 1.04 times.

Investigation of Polarization Mode Dispersion Influence to Different Optical Signal Modulation Formats

Increasing data rates in the fiber optics transmission systems leads to more new limiting factors which complicates the signal transmission. One of such factors is the optical fiber birefringence induced polarization mode dispersion (PMD). Although PMD value in typical standard single mode fiber is quite low (less than 0.2 ps/âkm for ITU-T G.652D standard fiber) higher data rates sets higher requirements for signal quality. In this research comparison between three different modulation formats (traditional on-off keying, differential phase shift keying (DPSK) and polarization shift keying (PolSK)) is given at different optical fiber PMD levels and data transmission rates. It is found that most significant impact of PMD is to traditional on-off keying modulation format, but the best performance showed DPSK modulated signals.