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1

Effect of viscosity on the far-field diffraction pattern of spatial self-phase modulation

Nibu A. G., Silpa S. S., Ardra S. N., Anisha M. M., Ambika D.

Optica Applicata

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2017

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Vol. 47, nr 4

591--599

EN

Effect of viscosity of a liquid on the far-field diffraction pattern due to spatial self-phase modulation is investigated. Chlorophyll extract in acetone at different concentrations is used as the low viscous nonlinear samples and commercial engine oils, synthetic and natural. It is also used as high viscous media. In the case of chlorophyll solution, the self-induced diffraction ring pattern in the far-field is a series of circular rings at the beginning; but later it is transformed to half circular symmetry. But for the high viscous engine oils we have observed circular fringes and there is no time dependent structural variation in the pattern. The coefficient of the intensity dependent nonlinear refractive index for all the liquid samples is evaluated.

2

Absorption coefficient along a propagated ultra-short laser pulse in the air based on Kramers–Kronig relations

Malekshahi M, Naghavi K

Optica Applicata

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2015

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Vol. 45, nr 4

501--512

EN

In this manuscript, some effects such as nonlinear Kerr, stimulated Raman, and plasma generation effects lead to obtaining the nonlinear refraction index of the air along an intense ultra-short laser pulse based on one-dimensional propagation analysis. The variations in the pulse frequency by the self-phase modulation effect are investigated for achieving the functionality of the refractive index to the frequency. The mentioned functionality allows implementing Kramers–Kronig relations to measure the absorption coefficient. Results indicate that the front of the laser pulse faces a high rate of the energy loss whereas the back of the pulse experiences a gain. The implementation of Kramers–Kronig relations for a theoretical calculation of absorption coefficient variation along a laser pulse propagating in the air in which we have simultaneously taken into account the three above-mentioned effects distinguishes our work from other studies.

3

Optical self-phase modulation using a new photonic crystal coupled-cavity waveguide

Bahadori-Haghighi S, Ghayour R

Optica Applicata

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2014

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Vol. 44, nr 1

29--38

EN

In this paper, self-phase modulation of an optical pulse using a new photonic crystal coupled-cavity waveguide is simulated and analyzed. The structure of the new coupled-cavity waveguide is introduced and its advantage over the previous type of coupled-cavity waveguide is discussed. In order to obtain a high group index over a large bandwidth and benefit from the slow light phenomenon, the group index and group velocity dispersion parameter curves of the guided mode are calculated. Finally, the transient simulation of the structure is performed using a finite-difference time-domain method. The calculated required length of the coupled-cavity waveguide for a maximum phase shift of π is about 31 μm. Spectral broadening of the optical pulse as a result of self-phase modulation is also presented and discussed.

4

Self-phase modulation of temporary overlapped chirped pulses.

Vankov A., Badziak J.

Optica Applicata

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2000

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Vol. 30, nr 2-3

431-442

EN

A self-phase modulation at amplification of temporary overlapped chirped, pulses is investigated. The analytical and numerical calculations are used to predict the effects of prepulse intensity increasing and additional satellites arising after recompression as well as the effects of spectrum broadening and shape distortion of the pulses. The experimental results are presented that agree well with the calculations.

5

Wpływ zjawiska samomodulacji fazy na transmisję danych wykorzystującą zjawisko konwersji modulacji częstotliwości

Perlicki K.

Kwartalnik Elektroniki i Telekomunikacji

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1998

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Vol. 44, nr 3

335-344

PL

W artykule przedstawiono analizę wpływu zjawiska samomodulacji fazy na parametry systemu transmisji danych wykorzystującego zjawisko konwersji modulacji częstotliwości na modulację amplitudy powodowaną przez dyspersję chromatyczną światłowodu z dwupoziomowym wyjściowym sygnałem optycznym. Artykuł jest kontynuacją publikacji [1], która zawiera podstawowe informacje dotyczące : zjawiska konwersji modulacji częstotliwości na modulację amplitudy w standardowym światłowodzie jednomodowym z dwupoziomowym optycznym sygnałem wyjściowym i systemu transmisji danych wykorzystującym efekt konwersji. W artykle skoncentrowano się wyłącznie na analizie wpływu nieliniowego zjawiska samomodulacji fazy na parametry omówionego w [1] systemu.

EN

The author investigate the impact of self - phase modulation on the FM-AM conversion supported transmission with a binary optical signal at the receveir. The propagation of optical field through a linear and nonlinear fiber is described by nonlinear Schrodinger equation, which is solved numerically by the split - step Fourier method. The computer simulations are caried out for a system with the following characteristics. The transmitted optical signal is modulated by an augmented PRBS of 7 length 2 - 1. The fiber dispersion is 17 ps/nm . km, the loss is 0,2 dB/km and the nonlinear coefficient is -1 -1 2,17 W km , the fiber length is from 100 to 200 km. Optical in - line amplifier is inserted at 100 km. The gain of the amplifier is chosen to compensation of the fiber loss. A first order Butterworth filter at the receiver is used. In particular impact of seff - phase modulation on signal to noise ratio is investigated. Results of numerical simulations show that interplay between dispersion of standard fiber and self - phase modulation increases signal to noise ratio.