We propose phase switching for either main-carrier or subcarriers of two consecutive signal blocks to achieve fading-free double-sideband direct-detection (DD). The proposed approach has twice of the electrical spectral efficiency (SE) of offset OFDM, and the same electrical SE as single-side band (SSB) OFDM. With this scheme, 40-Gb/s DD-OOFDM is successfully received over 80-km SSMF with single polarization and single detector.
"rthogonal frequency division multiplexing (OFDM) is now a well-established transmission solution for optical communication systems . Although optical OFDM with coherent detection has an improved performance, OFDM transmission in optical communication systems with direct detection (DD) is a major topic of investigation, either for application in long-haul and metropolitan networks     or access networks   . "
[Show abstract][Hide abstract] ABSTRACT: An analytical method based on the moment generating function (MGF) is proposed for assessing the performance of direct-detection (DD) orthogonal frequency division multiplexing (OFDM) optical receivers with radio-frequency (RF) demodulation. The MGF-based method is a generalization of the method previously reported in the literature for DD baseband OFDM optical receivers. The proposed method relies on the analytical derivation of equivalent filters that describe the combined effect of electrical filtering + RF demodulation + FFT operation + the equalizer of the OFDM receiver for the real and imaginary parts of the signal at the equalizer output. The method takes into account imperfections of the RF demodulator, namely, power and phase imbalance between the RF demodulator arms and different electrical filtering on its arms. Numerical results show excellent agreement between the bit error probability estimates provided by the proposed method and estimates obtained from Monte Carlo simulation, in the absence and presence of receiver imperfections.
Journal of Optical Communications and Networking 02/2014; 6(2):180-189. DOI:10.1364/JOCN.6.000180 · 2.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper, we propose and demonstrate phase switching for either main carrier or subcarriers of two consecutive signal blocks to achieve fading-free double-sideband direct-detection. The proposed approach has twice of the electrical spectral efficiency (SE) of offset OFDM, and the same electrical SE as single-side band OFDM. We perform numerical simulation and verify the system robustness against polarization mode dispersion and laser phase noise. Our experimental results show that 40-Gb/s direct-detection OOFDM can be successfully delivered over 80-km SSMF with single polarization and single detector.
[Show abstract][Hide abstract] ABSTRACT: A closed-form expression for the variance of the four-wave mixing (FWM) induced in each subcarrier of a double sideband orthogonal frequency division multiplexing (OFDM) system employing direct detection is proposed and validated. Particularly, using a small signal analysis, equivalent transfer functions that characterize the frequency response of the FWM effect are derived taking into account the walkoff effect between the modulated pump waves and the FWM wave. The accuracy of the variance estimates provided by the closed-form expression is assessed for different sets of system parameters. The closed-form expression provides good variance estimates of the FWM-induced degradation caused by degenerate and nonsymmetric nondegenerate FWM components. For symmetric non-degenerate FWM components, the proposed expression provides reliable but pessimistic variance estimates, not exceeding the actual FWM variance in 1.5 dB for modulation indexes of interest.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.