Spectrally-efficient Dual Phase-Conjugate Twin Waves with Orthogonally Multiplexed Quadrature Pulse-shaped Signals

Yoshida, Tsuyoshi; Sugihara, Takashi; Ishida, K.; Matsukawa, Takashi

doi:10.1364/ofc.2014.m3c.6

Cited by 29 publications

(21 citation statements)

References 7 publications

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“…Clearly the nonlinear mitigation is somewhat less than conjugating every signal, but due to the reduced excess bandwidth net performance gains in the region of 1.5dB have been observed. A more straightforward approach is of course the conjugate coding of pairs of signals [25,26] fully generalizing the 2x2 MIMO approach of [17]. This approach maintains the full nonlinearity mitigation benefit, but losses the signal to noise ratio benefit of coherent superposition [27] available when only one signal and its conjugate are used.…”

Section: Parallel Conjugated Copiesmentioning

confidence: 99%

Impact of Optical Phase Conjugation on the Nonlinear Shannon Limit

Ellis

Khateeb

McCarthy

2016

Optical Fiber Communication Conference

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Abstract:Compensation of the detrimental impacts of nonlinearity on long haul wavelength division multiplexed system performance is discussed, and the difference between transmitter, receiver and in-line compensation analyzed. The impact of system imperfections is also outlined.OCIS codes: (000.0000) General; (000.0000) General [8-pt. type] For codes, see http://www.osapublishing.org/submit/ocis/ IntroductionThe perception of the nonlinear Shannon limit [1] is currently seen as preventing the continued smooth (exponential) increase of optical transmission throughput, resulting in a predicted capacity crunch [2]. The focus of the research community on these issues has resulted in specific international discussion meetings [e.g. 3] and even significant inducement prizes [4]. One of the earliest proposals to compensate for nonlinear impairments in an optical transmission system was the use of optical phase conjugation (OPC) [5,6]. In an OPC system, the entire signal is phase conjugated after a certain length of a transmission system. If the signal is then propagated through an identical length, subject to certain symmetry conditions, nonlinear effects and even ordered dispersive effects are reversed. If the symmetry conditions are not met, then partial compensation of the impairments is still possible [7]. Following early work on direct detection systems [e.g. 8-10] which were severely constrained by nonlinearity, recent attention has focused on the digital signal processing capabilities enabled by nested Mach-Zhender modulators [11] and digital coherent receivers [12]. However, as we approach the nonlinear Shannon limit there is renewed interest in the direct compensation of nonlinear impairments. In this paper, we review recent progress in the use of optical conjugation for the mitigation of nonlinear impairments in both serial and parallel configurations, and estimate the extent to which each technique may enable transmission beyond the nonlinear Shannon limit.

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Section: Parallel Conjugated Copiesmentioning

confidence: 99%

Impact of Optical Phase Conjugation on the Nonlinear Shannon Limit

Ellis

Khateeb

McCarthy

2016

Optical Fiber Communication Conference

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“…This mitigation scheme is effective thanks to the narrow OFDM subcarrier spacing (tens of MHz), which enhances the correlation between nonlinear phase shifts of neighbouring subcarriers compared to temporally correlated PCTW (tens of GHz bandwidth). To avoid completely 50% loss in SE of PCTW scheme, a novel approach based on joint processing of two transmitted signal in x-and y-polarizations was proposed in [7]. In this scheme, two generated signals are mapped on two polarizations before PDM transmission as, E x =E 1 +E 2 , E y =E 1 *-E 2 *.…”

Section: Phase Conjugation Concept Formentioning

confidence: 99%

“…However, PCTW halves the spectral efficiency (SE) because of the 50% overhead associated with the transmission of the signal's phase conjugated copy. To address this problem, a dual PCTW scheme combined with quadrature pulse shaping was proposed for single carrier systems, yielding an improvement of ~1.2 dB [7] without any overhead. For coherent optical orthogonal frequency division multiplexing (CO-OFDM), a flexible nonlinear compensation scheme with the insertion of phase-conjugated pilots (PCP) was proposed in [8], allowing the overhead to be adjusted (up to 50%) according the required performance gain, up to a limit of ~4 dB.…”

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confidence: 99%

Optical and Digital Phase Conjugation Techniques for Fiber Nonlinearity Compensation

McCarthy

Turitsyn

et al. 2015

2015 Opto-Electronics and Communications Conference (OECC)

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“…Whilst Raman amplification and superchannels are becoming established, the optimum means to compensate nonlinearity is the focus of much research. Candidates include wide-bandwidth digital back propagation 4 , phase conjugate coding 5 and optical phase conjugation (OPC) [6][7][8] . OPC uniquely offers disruption of parametric noise amplification 3 thus overcomes the nonlinear Shannon limit 7 and 60% reach enhancement has been shown for a 1 Tbit/s signal 8 .…”

Section: Introductionmentioning

confidence: 99%