Enhancing Optical Signal-to-Noise Ratio in Terrestrial Cascaded EDFAs Fiber Optic Communication Links using Hybrid Fiber Amplifier

Ultra-long span unrepeatered systems using distributed Raman amplification are cost-effective solutions for bridging moderate transmission distances. However, there are two major limiting factors: nonlinear Kerr effect-induced nonlinear signal distortion and optical signal-to-noise ratio degradation due to spontaneous Raman noise. In this report, we proposed a model of three-segment hybrid fiber effective core area structure and developed a model covering: (1) generalized mathematical formulations, (2) analysis of three-segment Raman amplified link, and (3) simulation model of data transmission. The proposed model showed an improvement of the Raman gain profile, a reduction of the negative impact of the nonlinear Kerr effect, and an enhancement of the optical signal-to-noise ratio. A numerical simulation of the transmission performance of the three-segment hybrid structure was compared to conventional single-segment single fiber core structure on 80 Gb/s differential quadrature phase-shift keying (DQPSK) modulated data signals over a propagation distance of 390 km. The required optical signal-to-noise ratio was reduced by 2.71 dB to achieve the target error rate without using forward error correction. The numerical model and simulation of various data rates up to 100 Gb/s consistently showed that an improvement in transmission performance could be achieved by using three-segment hybrid fiber effective core area structure.

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New trend for optical signal-to-noise ratio of disturbed Raman fiber amplifier

Optik ◽

10.1016/j.ijleo.2013.11.018 ◽

2014 ◽

Vol 125 (11) ◽

pp. 2572-2576 ◽

Cited By ~ 3

Author(s):

Arwa H. Beshr ◽

Moustafa H. Aly ◽

A.K. AboulSeoud

Keyword(s):

Signal To Noise Ratio ◽

Fiber Amplifier ◽

Optical Signal ◽

Signal To Noise ◽

Raman Fiber Amplifier ◽

Noise Ratio

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Optical data signals in fiber optic communication links with fading

Information and Control Systems ◽

10.31799/1684-8853-2019-3-94-104 ◽

2019 ◽

pp. 94-104

Author(s):

I. Juwiler ◽

I. Bronfman ◽

N. Blaunstein

Keyword(s):

Spectral Efficiency ◽

Fiber Optic ◽

Fiber Optic Cable ◽

Optical Signals ◽

Dispersion Properties ◽

Optical Cable ◽

Time Dispersion ◽

Communication Links ◽

Fiber Optic Communication ◽

Optic Communication

Introduction: This article is based on the recent research work in the field of two subjects: signal data parameters in fiber optic communication links, and dispersive properties of optical signals caused by non-homogeneous material phenomena and multimode propagation of optical signals in such kinds of wired links.Purpose: Studying multimode dispersion by analyzing the propagation of guiding optical waves along a fiber optic cable with various refractive index profiles of the inner optical cable (core) relative to the outer cladding, as well as dispersion properties of a fiber optic cable due to inhomogeneous nature of the cladding along the cable, for two types of signal code sequences transmitted via the cable: return-to-zero and non-return-to-zero ones.Methods: Dispersion properties of multimode propagation inside a fiber optic cable are analyzed with an advanced 3D model of optical wave propagation in a given guiding structure. The effects of multimodal dispersion and material dispersion causing the optical signal delay spread along the cable were investigated analytically and numerically.Results: Time dispersion properties were obtained and graphically illustrated for two kinds of fiber optic structures with different refractive index profiles. The dispersion was caused by multimode (e.g. multi-ray) propagation and by the inhomogeneous nature of the material along the cable. Their effect on the capacity and spectral efficiency of a data signal stream passing through such a guiding optical structure is illustrated for arbitrary refractive indices of the inner (core) and outer (cladding) elements of the optical cable. A new methodology is introduced for finding and evaluating the effects of time dispersion of optical signals propagating in fiber optic structures of various kinds. An algorithm is proposed for estimating the spectral efficiency loss measured in bits per second per Hertz per each kilometer along the cable, for arbitrary presentation of the code signals in the data stream, non-return-to zero or return-to-zero ones. All practical tests are illustrated by MATLAB utility.

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