scholarly journals Imbalanced Mach-Zehnder Modulator for Fading Suppression in Dispersion-Uncompensated Direct Detection System

Electronics ◽  
2021 ◽  
Vol 10 (22) ◽  
pp. 2866
Author(s):  
Yixiao Zhu ◽  
Xin Miao ◽  
Qi Wu ◽  
Longjie Yin ◽  
Weisheng Hu
Keyword(s):  
Forward Error Correction ◽  
Direct Detection ◽  
Detection System ◽  
Single Mode ◽  
Pulse Amplitude ◽  
Single Mode Fiber ◽  
Error Rates ◽  
Transmission Experiment ◽  
Mach Zehnder Modulator ◽  
The Impact

In this work, we systematically analyze the impact of three kinds of Mach-Zehnder modulator (MZM) imbalances, including bias deviation, amplitude mismatch, and differential time skew in intensity-modulation direct-detection (IM-DD) links. It is shown that, for power fading limited transmission, the imbalances can be utilized as advantages rather than impairments. Specifically, the bias deviation with single-arm driven mode and amplitude mismatch with differential driven mode can increase the available bandwidth by shifting the frequency of fading notches. Meanwhile, time skew provides another way to avoid fading by shaping the double sideband (DSB) signal into a vestigial sideband (VSB) with an asymmetrical transfer function. In the transmission experiment, 34 Gbaud Nyquist 6/8-ary pulse amplitude modulation (PAM-6/8) signals are used for investigation in a 20 km dispersion-uncompensated standard single-mode fiber (SSMF) link. With the help of a Volterra nonlinear equalizer, all three kinds of imbalances can achieve bit-error rates (BERs) below the 7% and 20% hard-decision forward error correction (HD-FEC) thresholds for PAM-6 and PAM-8 signals, respectively. The received power sensitivity is also compared at the back-to-back (BTB) case and after fiber transmission. Both numerical simulation and experimental demonstration confirm that the dispersion-induced power fading can be effectively suppressed with bias, amplitude, or skew imbalance, providing a feasible solution for transmission distance extension of C-band DD links.

scholarly journals Multi-Twin-SSB Modulation with Direct Detection Based on Kramers–Kronig Scheme for Long-Reach PON Downstream

2019 ◽  
Vol 9 (4) ◽  
pp. 748 ◽  
Author(s):  
Xiang Gao ◽  
Yuancheng Cai ◽  
Bo Xu ◽  
Xiaoling Zhang ◽  
Kun Qiu
Keyword(s):  
Optical Networks ◽  
Forward Error Correction ◽  
Direct Detection ◽  
Chromatic Dispersion ◽  
Optical Network ◽  
Single Mode ◽  
System Optimization ◽  
Single Mode Fiber ◽  
High Data ◽  
Multi Band

As the demand for high data volumes keeps increasing in optical access networks, transmission capacities and distance are becoming bottlenecks for passive optical networks (PONs). To solve this problem, a novel scheme based on multi-twin single sideband (SSB) modulation with direct detection is proposed and investigated in this paper. At the central office, two SSB signals are generated simultaneously with the same digital-to-analog converters (DACs). The twin-SSB signal is not only robust against frequency selected power fading introduced by chromatic dispersion (CD), but also improves the spectral efficiency (SE). By combining a twin-SSB technique with multi-band carrier-less amplitude/phase modulation (multi-CAP), different optical network units (ONUs) can be supported by flexible multi-band allocation based on software-reconfigurable optical transceivers. The Kramers–Kronig (KK) scheme is adopted on the ONU side to effectively mitigate the signal–signal beat interference (SSBI) induced by the square-law detection. The proposed system is extensively studied and validated with four sub-bands using 50 Gbps 16 quadrature amplitude modulation (QAM) modulation for each sub-band using numerical simulations. Digital pre-equalization is introduced at the transmitter-side to balance the performance of different ONUs. After system optimization, a bit error rate (BER) threshold for hard decision forward error correction (HD-FEC) code with 7% redundancy ratio (BER = 3.8 × 10−3) can be reached for all ONUs over 50-km standard single-mode fiber.

scholarly journals Optical Power Budget of 25+ Gbps IM/DD PON with Digital Signal Post-Equalization

2020 ◽  
Vol 10 (17) ◽  
pp. 6106
Author(s):  
Aleksejs Udalcovs ◽  
Toms Salgals ◽  
Lu Zhang ◽  
Xiaodan Pang ◽  
Anders Djupsjöbacka ◽  
...  
Keyword(s):  
Optical Networks ◽  
Direct Detection ◽  
Optical Power ◽  
Digital Signal ◽  
Single Mode ◽  
Pulse Amplitude ◽  
Power Splitting ◽  
Power Budget ◽  
Sustainable Solutions ◽  
The Impact

While infrastructure providers are expanding their portfolio to offer sustainable solutions for beyond 10 Gbps in the access segment of optical networks, we experimentally compare several modulation format alternatives for future passive optical networks (PONs) aiming to deliver 25+ Gbps net-rates. As promising candidates, we consider the intensity modulation direct detection (IM/DD) schemes such as electrical duobinary (EDB) and 4-level and 8-level pulse amplitude modulations (PAM-4/8). They are more spectrally efficient than the conventional non-return-to-zero on-off-keying (NRZ-OOK) used in current 10G PONs. As we move to higher rates, digital equalization enhances the performance by smoothening the systems imperfection. However, the impact that such equalization has on the optical power budget remains unclear. Therefore, in this article, we fairly compare the optical power budget values of a time division multiplexed PON (TDM-PON) exploiting a linear digital signal equalization at the receiver side. We consider the conventional PON configuration (20 km of single-mode fiber (SMF), 1:N optical power splitting) with IM/DD and net-rates above 25 Gbps. Furthermore, we focus on a downstream transmission imposing the bandwidth limitations of 10G components using a digital filter before the detection. The obtained results show that the use of a digital post-equalization with 43 feed-forward (FF) and 21 feedback (FB) taps can significantly improve the signal quality enabling new alternatives and enhancing the optical power budget.

scholarly journals 400GbE Technology Demonstration Using CFP8 Pluggable Modules

2018 ◽  
Vol 8 (11) ◽  
pp. 2055 ◽  
Author(s):  
Yang Yue ◽  
Qiang Wang ◽  
Jian Yao ◽  
Jason O’Neil ◽  
Daniel Pudvay ◽  
...  
Keyword(s):  
Wavelength Division Multiplexing ◽  
Forward Error Correction ◽  
Optical Network ◽  
Form Factors ◽  
Single Mode ◽  
Pulse Amplitude ◽  
Single Mode Fiber ◽  
Current Status ◽  
Successful Implementation ◽  
Eye Diagram

In this article, we first review the current status of 400GBASE client-side optics standards and multi-source agreements (MSAs). We then compare different form factors for 400GE modules, including CFP8, OSFP and QSFP-DD. The essential techniques to implement 400GE, such as pulse amplitude modulation (PAM4), forward error correction (FEC) and a continuous time-domain linear equalizer (CTLE), are discussed. A 400GE physical interface card (PIC) in Juniper’s PTX5000 platform has been developed, conforming to the latest IEEE802.3bs standard. To validate the PIC’s performance, a commercial optical network tester (ONT) and the PIC are optically interconnected through two CFP8-LR8 modules. The CFP8-LR8 module utilizes eight optical wavelengths through coarse wavelength division multiplexing (CWDM). Each wavelength carries 50 Gb/s PAM4 signal. The signal transmits through 10 km of single mode fiber (SMF). The ONT generates framed 400GE signal and sends it to the PIC through the first CFP8 module. The PIC recovers the signal, performs an internal loopback, and sends 400GE signal back to the ONT through the second CFP8 module. The optical spectrum, eye diagram, receiver sensitivity, long time soaking results, and internal digital diagnosis monitoring (DDM) result are fully characterized. The pre-FEC bit error rate (BER) is well below the KP4 FEC threshold of 2.2 × 10−4. After KP4 FEC, error-free performance over 30 km of SMF is achieved. In this way, we demonstrate both the interoperation between the PIC and the ONT, as well as the interoperation between the two CFP8 modules. This demonstration represents the successful implementation of the 400GE interface in the core IP/MPLS router.

scholarly journals Experimental Study on 25 Gbps C-Band PON over up to 25 km SMF Using a 10G-Class DML + APD IM-DD System

Photonics ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 328
Author(s):  
Haoyi Wang ◽  
Pablo Torres-Ferrera ◽  
Valter Ferrero ◽  
Roberto Gaudino
Keyword(s):  
Amplitude Modulation ◽  
Direct Detection ◽  
Chromatic Dispersion ◽  
Optical Network ◽  
Single Mode ◽  
Pulse Amplitude ◽  
Single Mode Fiber ◽  
Passive Optical Network ◽  
Pulse Amplitude Modulation ◽  
Modulation Formats

In this paper we present an experimental analysis of several modulation formats (pulse amplitude modulation (PAM-2), quaternary pulse amplitude modulation (PAM-4) and electrical duobinary (EDB)) for passive optical network (PON) applications at 25 Gbps bit rate in a C-band 10G-class directly modulated lasers (DML) and avalanche photodiode (APD) intensity modulation and direct detection (IM-DD) system over a single mode fiber (SMF) of up to 25 km, optimizing DML operations and demonstrating that PAM-2 is a promising choice. We also theoretically and experimentally analyzed the channel frequency response of DML and SMF affected by DML chirp and SMF chromatic dispersion.

scholarly journals Influence of Even-Order Dispersion on Super-Sech Soliton Transmission Quality under Coherent Crosstalk

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
Aleksandra Panajotovic ◽  
Daniela Milovic ◽  
Anjan Biswas ◽  
Essaid Zerrad
Keyword(s):  
Fourth Order ◽  
Optical Network ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Higher Order ◽  
Trailing Edges ◽  
Even Order ◽  
Transmission Quality ◽  
The Impact ◽  
Order Dispersion

The transmission speed of optical network strongly depends on the impact of higher order dispersion. In presence of coherent crosstalk, which cannot be otherwise controlled by optical filtering, the impact of higher order dispersions becomes more pronounced. In this paper, the general expressions, that describe pulse deformation due to second- and fourth-order dispersions in a single-mode fiber, are given. The responses for such even-order dispersions, in presence of coherent crosstalk, are characterized by waveforms with long trailing edges. The transmission quality of optical pulses, due to both individual and combined influence of second- and fourth-order dispersions, is studied in this paper. Finally, the pulse shape and eye diagrams are obtained.

scholarly journals Nonlinearities Diminution in 40 Gb/s 256 QAM Radio over Fiber Link via Machine Learning Method

2019 ◽  
Author(s):  
Muhammad Usman Hadi
Keyword(s):  
Machine Learning ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Radio Over Fiber ◽  
Support Vector ◽  
Potential Candidate ◽  
Input Signal Power ◽  
Quadrature Phase ◽  
Fiber Link ◽  
Mach Zehnder Modulator

Machine learning (ML) methodologies have been looked upon recently as a potential candidate for mitigating nonlinearity issues in optical communications. In this paper, we experimentally demonstrate a 40-Gb/s 256-quadrature amplitude modulation (QAM) signal-based Radio over Fiber (RoF) system for 50 km of standard single mode fiber length which utilizes support vector machine (SVM) decision method to indicate an effective nonlinearity mitigation. The influence of different impairments in the system is evaluated that includes the influences of Mach-Zehnder Modulator nonlinearities, in-phase and quadrature phase skew of the modulator. By utilizing SVM, the results demonstrated in terms of bit error rate and eye linearity suggest that impairments are significantly reduced and licit input signal power span of 5dBs is enlarged to 15 dBs.

Demonstration of C-band 112G PAM-4 transmission over 80-km stand-single mode fiber based on direct-detection

2018 ◽  
Vol 424 ◽  
pp. 32-36
Author(s):  
Yiran Wei ◽  
Jianjun Yu ◽  
Jianyang Shi ◽  
Junwen Zhang ◽  
Jing He ◽  
...  
Keyword(s):  
Direct Detection ◽  
Single Mode ◽  
Single Mode Fiber

Efficient Blind Adaptive CSE to Reduce Cyclic Prefix Length in Direct Detection Optical OFDM Systems

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Asmaa Benieddi ◽  
Sid Ahmed Elahmar
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Group Velocity Dispersion ◽  
Signal To Noise Ratio ◽  
Single Mode ◽  
Optical Signal ◽  
Single Mode Fiber ◽  
Cyclic Prefix ◽  
Ofdm Systems ◽  
Blind Adaptive

AbstractDirect detection optical orthogonal frequency division multiplexing (DDO-OFDM) systems for a long-reach of standard single mode fiber (SSMF) require a large length of cyclic prefix (CP) to avoid the inter-symbol interference (ISI) effect caused by group velocity dispersion (GVD). Unfortunately, this method is inefficient due to the energy wasted in CP samples. In order to reduce the CP length and to mitigate the residual ISI, a novel blind adaptive channel shortening equalizer (CSE) is proposed in this paper. Based on the orthogonality between subcarriers in the fast Fourier transform (FFT) property, the proposed algorithm attempts to minimize the sum-squared correlation (SSCM) between each sample located in a well-defined window to update the CSE coefficients. Thus, the combined channel-CSE response is shortened. Therefore, it can cancel the residual ISI effect due to the GVD and the short CP length. The performance of the system is evaluated on basis of bit error rate (BER) versus optical signal to noise ratio (OSNR) for different CP lengths. The simulation results validate the new algorithm SSCM and show that it can reduce the CP length with a much better system improvement than existing algorithms.

scholarly journals 137 Gb/s PAM-4 Transmissions at 850 nm over 40 cm Optical Backplane with 25 G Devices with Improved Neural Network-Based Equalization

2019 ◽  
Vol 9 (23) ◽  
pp. 5095
Author(s):  
Qianwu Zhang ◽  
Yuntong Jiang ◽  
Hai Zhou ◽  
Chuanlu Deng ◽  
Shuaihang Duan ◽  
...  
Keyword(s):  
Neural Network ◽  
Forward Error Correction ◽  
Optical Power ◽  
Pulse Amplitude ◽  
Performance Comparison ◽  
Decision Feedback ◽  
Bit Rate ◽  
Optical Backplane ◽  
The Impact ◽  
Equalization Method

An improved neural network-based equalization method is proposed and experimentally demonstrated. The up-to-137 Gb/s transmission of four level pulse amplitude modulation (PAM-4) signals with 25 G class 850 nm optical devices is achieved over an in-house fabricated 40 cm optical backplane. An in-depth investigation is conducted regarding the impact of delayed taps and spans on equalization performance. A performance comparison of the proposed method with the traditional maximum likelihood sequence estimation (MLSE) and decision feedback equalization (DFE) is also undertaken. For the bit rate from 80 to 100 Gb/s, the proposed method achieves an adopted hard-decision forward error correction (HD-FEC) requirement at a received optical power (RoP) of −9 and −8 dBm, while DFE and MLSE cannot meet the HD-FEC requirement. When the bit rate increases from 120 to 137 Gb/s, the proposed equalization method still successfully maintains the acceptable system performance at an RoP of −4 and −2.5 dBm. Furthermore, the specific bit error rate (BER) performances for varied maximum achievable bit rate under different RoPs by applying MLSE and the proposed method are also analyzed. This provides an important potential solution to realize the future data centers.

A 75-km single-mode fiber transmission experiment at 565 Mbit/s using cost-effective constituents

1984 ◽  
Vol 2 (4) ◽  
pp. 406-414 ◽  
Author(s):  
J. Bernard ◽  
L. Jeunhomme ◽  
M. Jurczyszyn ◽  
G. Lavanant ◽  
S. Landais ◽  
...  
Keyword(s):  
Single Mode ◽  
Cost Effective ◽  
Single Mode Fiber ◽  
Transmission Experiment ◽  
Fiber Transmission
Sign in / Sign up

Export Citation Format

Share Document