Modified Gerchberg-Saxton Algorithm Based Electrical Dispersion Pre-Compensation for Intensity-modulation and Direct-detection Systems

Zou, Dongdong; Fan, Li; Wang, Wei; Yin, Mingzhu; Shu, Qi; Li, Zhaohui

doi:10.1109/jlt.2022.3143522

Cited by 24 publications

(22 citation statements)

References 38 publications

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“…This EDC scenario can be implemented with a chirp-free single drive MZM. The iterative GS algorithm could be implemented using a cascade of frequency or time domain filters [15], [17], operating on the transmitted data pattern with 2 samplesper-symbol [15] or 1 sample-per-symbol [17]. The algorithm illustrated in Fig.…”

Section: Fir Filter Optimizationmentioning

confidence: 99%

“…4 (a). The scheme presented here performs the basic iterative GS algorithm offline using a single impulse δ(t) function located at the center of the simulation window as input, as oppose to using the information bearing NRZ-OOK or PAM4 waveform as implemented in prior studies [15], [17], [23]. With every successive iteration of the GS algorithm the impulse response of required electronic dispersion pre-compensating filter at iteration i, denoted, h i GS (n), becomes manifest.…”

Section: Single Real-valued Firmentioning

confidence: 99%

“…Although the basic iterative GS algorithm is guaranteed to converge, there is no guarantee the obtained solution is at the global optimum, as oppose to trapping at a local optimum. In previous studies, efforts have been made to "escape" the local optimum trap through, for example, perturbing the solution via reverse correction factors [17], insertion of pilot symbols [19] or multi-constraint optimization [20]. These efforts have also the added advantage of speeding up convergence.…”

Section: Single Real-valued Firmentioning

confidence: 99%

“…The iterative algorithm fundamentally linearizes the IM/DD channel effect including square-law detection. This algorithm was experimentally demonstrated to deliver 56 Gb/s over 50 km in [16], modified to reduce the implementation complexity and speed up convergence in [17], [18], [20], [23], [24], and implemented at the receiver as a data-aided decision directed equalizer, enabling 100 Gb/s over 100 km of single mode fiber (SMF) [19], [20], [24]. A 56 Gb/s PAM4 was transmitted over 80 km of SMF with only 5 iterations of the modified GS algorithm and a FIR noise shaping filter [23].…”

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confidence: 99%

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Gerchberg-Saxton Based FIR Filter for Electronic Dispersion Compensation in IM/DD Transmission Part I: Theory and Simulation

Karar

2023

J. Lightwave Technol.

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Intensity-modulation and direct-detection (IM/DD) transmission over short-reach optical fiber links, require electronic dispersion compensation (EDC) at the transmitter and/or electronic equalization at the receiver. Recently, the iterative Gerchberg-Saxton (GS) algorithm was demonstrated for EDC in IM/DD systems, through treating the amplitude at the transmitter and the phase prior-to the direct detection receiver as a degree of freedom. In Part I of this work, three GS approaches using finite impulse response (FIR) filters for EDC in IM/DD systems are demonstrated. The first two are closely related and rely on a cascaded FIR structure, while the third offers a novel noniterative EDC solution using a single GS optimized static FIR filter. This is achieved through decoupling pattern dependent aspects of transmission from the GS iterations by targeting a single impulse at the DD receiver. With every successive iteration an impulse response for the GS filter emerges and sets the FIR tap weights. It is also demonstrated that closed-form analytical expressions for the GS filter impulse response can be obtained through small-signal frequency-domain analysis. The FIR filter is simulated using 8-bit finite-precision arithmetic. An adaptive T -spaced post feed-forward equalizer (FFE) is utilized for mitigating residual chromatic dispersion. It is shown, that a T /2-spaced pre-EDC FIR filter with 417 taps can support 56 Gb/s non-return-to-zero (NRZ) on-off keying (OOK) transmission over 80 km of single mode fiber (SMF) with a chirp-free Mach-Zehnder modulator (MZM). Part II of this work, presents experimental demonstration of the non-iterative GS FIR filter proposed and simulated in this article.

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Section: Fir Filter Optimizationmentioning

confidence: 99%

Section: Single Real-valued Firmentioning

confidence: 99%

Section: Single Real-valued Firmentioning

confidence: 99%

mentioning

confidence: 99%

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Gerchberg-Saxton Based FIR Filter for Electronic Dispersion Compensation in IM/DD Transmission Part I: Theory and Simulation

Karar

2023

J. Lightwave Technol.

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“…The iterative algorithm fundamentally linearizes the IM/DD channel effect including square-law detection. This algorithm was experimentally demonstrated to deliver 56 Gb/s over 50 km in [16], modified to reduce the implementation complexity and speed up convergence in [17], [18], [20], and implemented at the receiver as a data-aided decision directed equalizer, enabling 100 Gb/s over 100 km of single mode fiber (SMF) [19], [20]. A 56 Gb/s PAM4 was transmitted over 80 km of SMF with only 5 iterations of the modified GS algorithm and a FIR noise shaping filter [23].…”

mentioning

confidence: 99%

Gerchberg-Saxton Based FIR Filter for Electronic Dispersion Compensation in IM/DD Transmission Part I: Theory and Simulation

Karar¹

2022

Preprint

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Intensity-modulation and direct-detection (IM/DD) systems deployed for short reach optical fiber links require electronic dispersion compensation (EDC) at the transmitter and/or electronic equalization at the receiver. Under direct detection, the optical phase is lost and complex-valued compensation of chromatic dispersion (CD) used in coherent systems could not be adopted. The utilization of the iterative Gerchberg-Saxton (GS) algorithm for EDC in IM/DD systems, has been demonstrated in theory and experiment, through treating the amplitude at the transmitter and the phase prior-to the direct detection receiver as a degree of freedom. In this article, three GS approaches for CD compensation in IM/DD systems using finite impulse response (FIR) filters are described and demonstrated. The first two approaches are closely related and rely on a cascaded FIR structure, while the third approach offers a novel non-iterative solution for EDC in IM/DD systems. In this solution, a feed-forward static digital FIR filter is designed and optimized using the Gerchberg-Saxton algorithm for transmitter CD pre-compensation. This is achieved through decoupling of pattern dependent and modulation format dependent aspects of transmission from the GS iterations by setting the target amplitude at the receiver to single impulse at the center of the time-window. With every successive iteration an impulse response for the CD pre-compensation filter emerges and is used to set the FIR tap weights. It is also demonstrated that the same optimum taps weight can be obtain analytically by applying the frequency-domain fiber transfer function to the iterations of the GS algorithm under the assumptions of small-signal analysis. The FIR filter is implemented using a non-recursive tapped delay line structure with an 8-bit finite-precision arithmetic. An adaptive $T$-spaced feed-forward equalizer (FFE) is utilized at the receiver for compensating residual CD. It is shown, as an example, that a 56 Gb/s non-return to zero (NRZ) on-off keying (OOK) signal could be transmitted over 80 km of single mode fiber (SMF) with a chirp-free single drive Mach-Zehnder modulator (MZM) and a 417-tap FIR filter operating at 2 sample-per-symbol with the bit error ratio (BER) below the hard-decision forward error correction (FEC) limit of $3.8 \times 10^{-3}$. Enabling a 21-tap post-FFE, reduces the BER to a 1 dBQ margin below the FEC limit.

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A novel approach integrating CFBG and optical filters to mitigate CD and PMD effects in high speed DWDM fiber optic links

Sreeragi,

Vijayakumar,

Pradeep

2024

Opt Quant Electron

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Modified Gerchberg-Saxton Algorithm Based Electrical Dispersion Pre-Compensation for Intensity-modulation and Direct-detection Systems

Cited by 24 publications

References 38 publications

Gerchberg-Saxton Based FIR Filter for Electronic Dispersion Compensation in IM/DD Transmission Part I: Theory and Simulation

Gerchberg-Saxton Based FIR Filter for Electronic Dispersion Compensation in IM/DD Transmission Part I: Theory and Simulation

Gerchberg-Saxton Based FIR Filter for Electronic Dispersion Compensation in IM/DD Transmission Part I: Theory and Simulation

A novel approach integrating CFBG and optical filters to mitigate CD and PMD effects in high speed DWDM fiber optic links

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