Informatics Publishing Limited

T. Sabapathi ¹, I. Thanga Dharsni ¹

Affiliations
1 Department of Electronics and Communication Engineering, Mepco Schlenk Engineering College, Sivakasi, Tamilnadu, IN

Abstract

Photonic generation of UWB signals is an emerging technique as it requires no complex optical-electrical or electrical-optical conversion. There are a number of techniques employed to generate lower order UWB signals photonically. But applications that uses UWB signals demands higher order wave. Also the generation scheme should consider optimum hardware utility and inturn the reconfigurability of the components used. Considering these criteria this paper analyses the techniques of generating UWB signals using optical amplifiers. Optical amplifiers that works based on the principal of spontaneous and stimulated emission has the inherent property of reconfigurability in response to the applied bias current and its dopant concentration. Utilizing these properties this paper aims at generating higher order UWB signals using optical amplifiers.

Keywords

Semiconductor Optical Amplifier (SOA), Erbium Doped Fiber Amplifier (EDFA), Power Spectral Density (PSD), Mach Zehnder Modulator (MZM), Ultra Wide Band.

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T. Sabapathi ¹, G. Jaya Brindha ¹

Affiliations
1 Department of Electronics and Communication Engineering, Mepco Schlenk Engineering College, Sivakasi, Tamilnadu, IN

Abstract

Non linear effects play a major role in hindering the progress of optical communication systems in terms of higher data rates and long haul transmissions. Maximum Likelihood Sequence Detection (MLSD) has been proposed to combat the nonlinear effects in optical channels. The main objective is to extract the original signal from the received signal which is distorted due to the non linear effects arising in the fiber. MLSD is an optimum detector as it uses the Viterbi detection through the Trellis structure. In this paper, the impact of SRS in the transmitted signal and its mitigation by MLSD are analyzed. MLSD is implemented for DWDM systems with 4 and 8 channels and its performance is compared with the direct detection receivers.

Keywords

Maximum Likelihood Sequence Detection (MLSD), WDM Systems, Stimulated Raman Scattering, Viterbi Detector.

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T. Sabapathi ¹, R. Gayathri ¹

Affiliations
1 Department of Electronics and Communication Engineering, Mepco Schlenk Engineering College, Sivakasi-626005, IN

Abstract

Dense Wavelength Division Multiplexing (DWDM) enables the utilization of a significant portion of the available fiber bandwidth by allowing many independent signals to be transmitted simultaneously on one fiber, with each signal located at a different wavelength. In this paper, the two major non-linear effects such as FWM and SRS in transmission fiber must be simultaneously eliminated by Duobinary Modulation to achieve successful communication. The results taken for 4, 8, 16, 32 and 64 channels are carried out by using OPTSIM software.

Keywords

SRS, FWM, DWDM, Duobinary Modulation.

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T. Sabapathi ¹, H. Muneera Begum ¹

Affiliations
1 Department of Electronics and Communication Engineering, Mepco Schlenk Engineering College, Sivakasi, Tamilnadu, IN

Abstract

The explosive growth of the Internet urges the quantum leap in the transmission capacity of the optical fiber network. In long-haul DWDM systems, Cross-phase modulation is the dominant nonlinearity that impairs the system's performance. Cross-phase modulation (XPM) will turn to intensity modulation by fiber dispersion and will cause the pulse's distortion. Hence, there is a need to suppress cross phase modulation in order to increase transmission capacity. Optical Phase Conjugation is one of the methods to reduce impairments due to cross phase modulation. Besides intensity modulation, DQPSK modulation is carried out to increase bit rate. The technique presented is the simplest and produces good results for high power laser source. This paper analyses the effect of cross phase modulation in DWDM system and it is experimentally analyzed using OPTSIM (Optical Communication Simulator).

Keywords

DQPSK (Differential Quadrature Phase Shift Keying), Cross Phase Modulation (XPM), DWDM, Optical Phase Conjugator (OPC), Kerr Non Linearity.

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T. Sabapathi ¹, K. Bavithra ²

Affiliations
1 Department of Electronics and Communication Engineering, Mepco Schlenk Engineering College, Sivakasi, Tamilnadu, IN
2 Mepco Schlenk Engineering College, Sivakasi,Tamilnadu, IN

Abstract

Cross-Phase Modulation is one of the major interchannel nonlinearity which occurs in multichannel systems. It is a nonlinear effect where the intensity of the optical signal propagating through the fiber alters the refractive index of the transmission medium through the Kerr effect. This causes phase shift between the co-propagating signals and polarisation rotations even in the absence of polarisation mode dispersion. We theoretically and experimentally analyse the effects of XPM using OPTSIM simulator. A method to reimburse the effects of XPM is also proposed.

Keywords

Cross Phase Modulation, Refractive Index, Phase Shift, Polarisation Rotations, Polarisation Mode Dispersion.

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T. Sabapathi ¹, B. S. Nanthini Devi ¹

Affiliations
1 Department of ECE, Mepco Schlenk Engineering College, Sivakasi, Tamilnadu, IN

Abstract

In DWDM system, the major non-linearities such as SRS and FWM occurs simultaneously in Long-Haul Communication. As the optical signal propagate through the fiber undergoes power fluctuations and crosstalk between the channels in DWDM system. Due to this major problem, the performance of DWDM system get degrades. In this paper, the effect of SRS and FWM affecting the original Dense Wavelength Division Multiplexed (DWDM) signal power simultaneously is studied and its effect on unequal channel spacing and dispersion is analyzed in fiber optic link. The unequal channel spacing and dispersion are common methods to mitigate the effect of both SRS and FWM in the transmission fiber of DWDM system. This paper also dealt how the combined effect of SRS and FWM makes the signal strength weaken in Long-Haul Communication. The Power Tilt value is compared with unequal channel spacing and unequal channel with dispersion co-efficient.

Keywords

DWDM, SRS, FWM, Power Tilt, Unequal Channel Spacing, Equal Channel Spacing, Dispersion.

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