Nonlinear noise spectrum measurement using a probability-maintained noise power ratio method

Ye, Tong; Su, Xiaofei; Zhang, Ke; Yang, Chengwu; Li, Jingnan; Fan, Yangyang; Nakashima, Hideharu; Hoshida, Takeshi; Tao, Zhenning

doi:10.1038/s44172-022-00047-y

Cited by 6 publications

(3 citation statements)

References 48 publications

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“…To practically and accurately estimate the nonlinear system performance from the device nonlinear characteristics, a new test signal other than the conventional single-tone or multi-tone signal is expected. For example, the probability-maintained notch method accurately and practically measures the equivalent nonlinear noise [177]. Moreover, new fiber, device, and system designs are still a more practical way to mitigate the nonlinear distortion.…”

Section: Advances In Science and Technology To Meet Challengesmentioning

confidence: 99%

Roadmap on optical communications

Agrell,

Karlsson,

Poletti

et al. 2024

J. Opt.

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The Covid-19 pandemic showed forcefully the fundamental importance broadband data communication and the internet has in our society. Optical communications forms the undisputable backbone of this critical infrastructure, and it is supported by an interdisciplinary research community striving to improve and develop it further. Since the first ‘Roadmap of optical communications’ was published in 2016, the field has seen significant progress in all areas, and time is ripe for an update of the research status. The optical communications area has become increasingly diverse, covering research in fundamental physics and materials science, high-speed electronics and photonics, signal processing and coding, and communication systems and networks. This roadmap describes state-of-the-art and future outlooks in the optical communications field. The article is divided into 20 sections on selected areas, each written by a leading expert in that area. The sections are thematically grouped into four parts with 4–6 sections each, covering, respectively, hardware, algorithms, networks and systems. Each section describes the current status, the future challenges, and development needed to meet said challenges in their area. As a whole, this roadmap provides a comprehensive and unprecedented overview of the contemporary optical communications research, and should be essential reading for researchers at any level active in this field.

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Section: Advances In Science and Technology To Meet Challengesmentioning

confidence: 99%

Roadmap on optical communications

Agrell,

Karlsson,

Poletti

et al. 2024

J. Opt.

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“…Unlike coherent transmission systems for which fiber Kerr nonlinearity is the most dominant form of nonlinear distortion beyond transceiver (Tx and Rx) nonlinear transfer functions, short reach optical interconnects suffer from nonlinear distortions due to a variety of source [15,17] such as: modulator nonlinear transfer functions, SSBI, Kerr nonlinearity inducing self and cross phase modulation, and modulator chip interaction with chromatic dispersion after direct detection. The VNLE has been successfully applied to systems employing directly modulated lasers [15,24,3,25], or electroabsorption modulators [17] with direct detection. The VNLE is based on the Taylor series expansion of the discrete-time Volterra model for which the restricted third order (p = 3) kernel is sufficient in most direct-detection optical communication applications and is expressed below [17,26]:…”

Section: Volterra Nonlinear Equalizermentioning

confidence: 99%

Electronic Dispersion Compensation and Functional Link Neural Network Equalization for IM/DD Links

Al-Barakah¹,

Karar²,

Ghandour³

et al. 2023

Preprint

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<p>Short-reach fiber optical links employing intensity modulation (IM) at the transmitter (Tx) and direct detection (DD) at the receiver (Rx), suffer from linear and nonlinear sources of impairments due to the interaction of chromatic dispersion (CD) with DD. In this article, joint electronic dispersion compensation (EDC) at the Tx, using two distinct Gerchberg-Saxton (GS) based approaches, and at the Rx, using a functional link neural network (FLNN) equalizer is demonstrated for IM/DD transmission. The first Tx approach utilizes the modified iterative GS algorithm, which partially mitigate linear and nonlinear sources of inter-symbol interference (ISI). The second Tx pre-EDC approach only pre-compensates for the linear power fading effect through implementing a GS based finite impulse response (FIR) filter. At the Rx, a T/2-spaced or T-spaced adaptive post-feed forward equalizer (FFE) is employed to fully compensate residual chromatic dispersion prior to attempting nonlinear equalization. Furthermore, a Volterra nonlinear equalizer (VNLE) is introduced to benchmark the performance and complexity of the FLNN, Subsequently, either a FLNN or a VNLE are utilized for nonlinear system identification and subsequent post-equalization mitigating uncompensated nonlinear sources of ISI. The FLNN nonlinear taps resulting from the functional expansion block are optimized using the recursive least square (RLS) algorithm. The Tx-FIR and Rx-FLNN enable 112 Gbit/s non-return to zero (NRZ) on off keying (OOK) transmission over 20 km of single mode fiber (SMF) and 112 Gbit/s 4- level pulse-amplitude modulation (PAM-4) transmission over 10 km of SMF. It is shown that the use of Tx pre-EDC reduces the complexity of the required equalization at the Rx. In addition, the FLNN was found to offer a 74% reduction in computational complexity relative to the third-order VNLE.</p>

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“…Orthogonal component analysis, which uses a finite impulse response (FIR) filter to separate the optimal linear approximation (i.e., correlated component) and residual nonlinear distortion (i.e., orthogonal component) from the nonlinear device output, has been applied to accurately estimate the nonlinear distortion of devices in optical communication systems [8]. However, this approach has many issues [9]. For example, it requires an accurate measurement of input and output waveforms, which requires expensive instruments (e.g., digital storage oscilloscope (DSO)).…”

Section: Introductionmentioning

confidence: 99%

Characterization of Nonlinear Distortion in Intensity Modulation and Direct Detection Systems

et al. 2023

J. Lightwave Technol.

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Intensity modulation and direct detection (IM-DD) systems are widely used in short-reach optical networks. Thus, developing a practical and accurate method to characterize nonlinear distortion and to estimate system performance is essential, as this is the foundation of IM-DD system design. The amount of nonlinear distortion can be characterized using the noise-to-power ratio (NPR). Although measuring the NPR using a notch requires only a spectrum analyzer, this method cannot be applied to a nonlinear system with non-Gaussian stimuli in general. We employ the method of measuring the NPR using a notch to characterize the nonlinear distortion in directly modulated distributed feedback (DM-DFB) laser-based IM-DD systems. Nonlinear distortion in these IM-DD systems can be attributed to two specific mechanisms: the imperfect power-current characteristic of the DM-DFB laser and the interaction among the modulation, chromatic dispersion (CD), and detection. Experimental results demonstrated that the nonlinear distortion can be accurately characterized with a mean absolute error of 0.47 dB, even when the stimuli are pulse amplitude modulation. The system performance subjected to nonlinearity could be estimated by the equivalent additive noise model. Besides, the method of measuring the NPR using a notch is also effective when the Mach-Zehnder modulator-based IM-DD system has nonnegligible CD. However, it failed in the case of negligible CD. Considering that this method is not always effective, we analyzed the attributes of various nonlinear systems and found that the above method is applicable only to systems dominated by second-order nonlinearity.

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Nonlinear noise spectrum measurement using a probability-maintained noise power ratio method

Cited by 6 publications

References 48 publications

Roadmap on optical communications

Roadmap on optical communications

Electronic Dispersion Compensation and Functional Link Neural Network Equalization for IM/DD Links

Characterization of Nonlinear Distortion in Intensity Modulation and Direct Detection Systems

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