Beyond 200 Gbps per Lane Intensity Modulation Direct Detection (IM/DD) Transmissions for Optical Interconnects: Challenges and Recent Developments

Pang, Xiaodan; Ozoliņš, Oskars; Udaļcovs, Aleksejs; Lin, Rui; Schatz, Richard; Westergren, Urban; Xiao, Shilin; Hu, Weisheng; Jacobsen, Gunnar; Popov, Sergei; Chen, Jiajia

doi:10.1364/ofc.2019.w4i.7

Cited by 19 publications

(13 citation statements)

References 16 publications

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“…The post filter is used to eliminate the enhanced in-band noise, which is defined as z(k) = r(k) + α × r(k − 1). MLSD is employed to recover the transmitted signal x(k) from the z(k), which is equivalent to minimize k {z(k) − [x(k) + α × x(k − 1)]} 2 . Figure 2(a) shows BER versus ROP for 129-Gbit/s optical PAM8 system using T-spaced Adam-based PNLE and LFFE after optical BTB transmission and 2-km SSMF transmission.…”

Section: Experimental Setups and Resultsmentioning

confidence: 99%

“…where h (1) k , h (2) k,l and h (3) k,l,m are the tap coefficients of 1st, 2nd and 3rd terms in VNLE, respectively. As a simplified version of VNLE, three-order PNLE has been proposed to compensate the nonlinear distortions in order to make a trade-off between computational complexity and performance.…”

Section: Principle Of Adam-based Pnlementioning

confidence: 99%

“…In recent years, development of data center drives demand of optical interconnects with data rate up to 400 Gbit/s. By 2020, the optical interconnects are expected to reach data rate of 800 Gbit/s or 1 Tbit/s [1][2][3]. To transmit high-capacity signal on limited bandwidth, multi-level modulations have been widely investigated in research and commercial fields.…”

Section: Introductionmentioning

confidence: 99%

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Adaptive moment estimation for polynomial nonlinear equalizer in PAM8-based optical interconnects

Zhou¹,

Wang²,

Wei³

et al. 2019

Opt. Express

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Adaptive moment estimation (Adam) is a popular optimization method to estimate large-scale parameters in neural networks. This paper proposes the first use of Adam algorithm to fast and stably converge large-scale tap coefficients of polynomial nonlinear equalizer (PNLE) for 129-Gbit/s PAM8-based optical interconnects. PNLE is one of simplified Volterra nonlinear equalizer for making a trade-off between complexity and performance. Different from serial least-mean square (LMS) adaptive algorithm, Adam algorithm is a parallel processing algorithm, which can obtain globally optimal tap coefficients without being trapped in locally optimal tap coefficients. Timing error is one of the main obstacles to the PAM systems with high baud rate and high modulation order. Owing to parallel processing and global optimization, Adam algorithm has much better performance on resisting the timing error, which can achieve faster, more-stable and lower-MSE convergence compared to LMS adaptive algorithm. In conclusion, Adam algorithm shows great potential for converging the tap coefficients of PNLE in PAM8-based optical interconnects.

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Section: Experimental Setups and Resultsmentioning

confidence: 99%

Section: Principle Of Adam-based Pnlementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Adaptive moment estimation for polynomial nonlinear equalizer in PAM8-based optical interconnects

Zhou¹,

Wang²,

Wei³

et al. 2019

Opt. Express

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“…Notably, intra-datacenter traffic with a typical link distance shorter than 2 km accounts for more than 80% of global traffic [2][3]. Such links require ultrahigh-speed interconnections (>100 Gb/s/) and significant experimental progress has already been achieved in this direction [4][5]. Even though coherent transmission systems exhibit superior performance [6], they generally result in a complex, power-hungry and costly system architectures, which have so far been deemed unsuitable for such short-distance implementations.…”

Section: Introductionmentioning

confidence: 99%

Multi-Band Direct-Detection Transmission Over an Ultrawide Bandwidth Hollow-Core NANF

Hong

Sakr

Taengnoi

et al. 2020

J. Lightwave Technol.

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In this paper, we report high-speed multi-band direct-detection (DD) transmission over a hollow-core nested antiresonant nodeless fiber (NANF). Thanks to the ultrawide bandwidth of the NANF, we demonstrate dual-band transmission across the O-and C-bands over a ~1-km length of a hollow-core fiber for the first time. Eight wavelength-division multiplexed (WDM) channels were transmitted using 100-Gb/s/ Nyquist 4-ary pulse-amplitude modulation (PAM4) signals, which to the best of our knowledge, is the highest aggregate capacity ever transmitted in a DD hollow-core fiber-based transmission system. Optical pre-amplification was adopted for signal reception in both bands, achieved using an in-house built bismuth-doped optical fibre amplifier (BDFA) and a commercial erbium-doped fiber amplifier (EDFA) in the O-and C-band, respectively. We further demonstrate beyond 100-Gb/s/λ adaptively-loaded discrete multitone (DMT) transmission over the S+C+L-bands using the same NANF, without the use of optical amplification. Our experiments show that apart from fiber loss, the use of the NANF did not introduce any additional transmission penalties. The demonstrated results validate the ultrawide bandwidth and excellent modal purity of the fabricated NANF, which allow beyond 100-Gb/s/ penalty-free transmission over multiple bands, highlighting the potential of this fiber technology for high-speed short-to intermediate-reach applications.

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“…Optical fiber transmission has evolved over decades and been widely recognized as the most cost-and energy-efficient technique to offer ultra-high capacity [1,2]. The datacenter I/O port transmission speed is soon approaching 200-Gbps per lambda [3]. To meet such a high data rate, the intensity modulation direct detection (IM/DD) systems with advanced modulation formats such as pulse amplitude modulation (PAM) or discrete multi-tone (DMT) have been experimentally demonstrated [4][5][6][7][8]13].…”

Section: Introductionmentioning

confidence: 99%

Kernel mapping for mitigating nonlinear impairments in optical short-reach communications

Westergren¹,

Pang²,

Udaļcovs³

et al. 2019

Opt. Express

Self Cite

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Nonlinear impairments induced by the opto-electronic components are one of the fundamental performance-limiting factors in high-speed optical short-reach communications, significantly hindering capacity improvement. This paper proposes to employ a kernel mapping function to map the signals in a Hilbert space to its inner product in a reproducing kernel Hilbert space, which has been successfully demonstrated to mitigate nonlinear impairments in optical short-reach communication systems. The operation principle is derived. An intensity modulation/direct detection system with 1.5-µm vertical cavity surface emitting laser and 10-km 7core fiber achieving 540.68-Gbps (net-rate 505.31-Gbps) has been carried out. The experimental results reveal that the kernel mapping based schemes are able to realize comparable transmission performance as the Volterra filtering scheme even with a high order.

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Beyond 200 Gbps per Lane Intensity Modulation Direct Detection (IM/DD) Transmissions for Optical Interconnects: Challenges and Recent Developments

Abstract: All parts of an IM/DD system are being stretched to the limit as the single lane data rate approaches 200 Gbps and beyond. We report the recent developments on the key enablers conquering this target.

Cited by 19 publications

References 16 publications

Adaptive moment estimation for polynomial nonlinear equalizer in PAM8-based optical interconnects

Adaptive moment estimation for polynomial nonlinear equalizer in PAM8-based optical interconnects

Multi-Band Direct-Detection Transmission Over an Ultrawide Bandwidth Hollow-Core NANF

Kernel mapping for mitigating nonlinear impairments in optical short-reach communications

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