Article

# Numerical simulation of the SPM penalty in a 10-Gb/s RZ-DPSK system

Bell Labs., Murray Hill, NJ, USA

IEEE Photonics Technology Letters (Impact Factor: 2.04). 12/2003; DOI: 10.1109/LPT.2003.818664 Source: IEEE Xplore

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**ABSTRACT:**Carrier density fluctuations in semiconductor optical amplifiers (SOAs) impose penalties on phase-shift keying (PSK) signals due to nonlinear phase noise (NLPN), and on-off keying (OOK) signals due to self-gain modulation. In this paper, we pro-pose a simple scheme to equalize the impairments induced by SOA nonlinearities, derived from the small signal analysis of carrier density fluctuations. We demonstrate via simulation almost com-plete cancelation of the NLPN added by a saturated SOA on a differential PSK signal. We demonstrate via both simulations and experiment the effectiveness of the method for mitigation of non-linear distortions imposed by SOAs on an OOK signal.Journal of Lightwave Technology 02/2010; 28(1). · 2.56 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We develop a novel phasor monitor to obtain the constellation diagram from asynchronously sampled data measured by using the delay-detection technique. This phasor monitor consists of three parts; a phase-adjustment-free delay-interferometer, an optical front-end made of three photodetectors, and analog-to-digital (A/D) convertors, and a digital signal processor. We operate the A/D convertor at the sampling rate much slower than the symbol rate and acquire the data asynchronously. However, despite the use of such a slow and asynchronous sampling rate, we obtain the clear eye and constellation diagrams by utilizing the software-based synchronization technique based on a novel phased-reference detection algorithm. Thus, the proposed phasor monitor can be implemented without using high-speed A/D convertors and buffer memories, which have been the major obstacles for the cost-effective realization of the phasor monitor. For a demonstration, we realize the proposed phasor monitor by using an A/D converter operating at 9.77 MS/s and used it for the constellation monitoring and bit-error-rate (BER) estimation of 10.7-Gsymbol/s differential quadrature phase-shift keying (DQPSK) and differential 8-ary phase-shift keying (D8PSK) signals.Optics Express 10/2010; 18(21):21511-8. · 3.55 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**The influence of chromatic dispersion, optical power, and nonlinear distortions in a fibre-optic communication system on the quality of data transmission based on nonreturn-to-zero differential phase-shift keying at a rate of 40 Gbit s-1 in one spectral channel have been numerically simulated and experimental studied. The results of direct numerical calculations and estimates based on the quality factor (Q factor) are in qualitative agreement with the experimental data. It is found experimentally that the dependence of the error rate on the accumulated dispersion has a plateau in the range from —50 to 50 ps nm-1; a similar dependence is obtained in the numerical calculation based on the Q factor. The optimal calculated value of the power launched into each of 10 sections of a line with a total length of 1000 km is 2 — 4 dBm; it corresponds to the experimental value of 3 dBm.Quantum Electronics 01/2011; 41(10):929-933. · 0.82 Impact Factor

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