Solutions for 100/400-Gb/s Ethernet Systems Based on Multimode Photonic Technologies

In this paper, we experimentally demonstrate the transmission of 112 Gb/s four-level pulse amplitude modulation over 100-m OM4 multimode fiber employing a multimode 850-nm vertical-cavity surface-emitting laser (VCSEL) at the transmitter side and equalization techniques at the receiver's digital signal processing (DSP). The penalties imposed by the strong bandwidth limitations due to the optical components as well as the low modal bandwidth of the fiber are compensated by three variant DSP schemes at the receiver, i.e., 1) a finite-impulse response (FIR) filter, 2) a maximum likelihood sequence estimation equalizer (MLSE), and 3) an FIR filter followed by an MLSE equalizer (FIR/MLSE) in a cascaded form. We evaluate all three aforementioned equalization schemes under two different transmitter implementations, i.e., employing a 30-GHz arbitrary waveform generator and a lower bandwidth 15-GHz commercially available digital-to-analog converter and we infer about the applicability of each DSP scheme under these implementations. We show that the hybrid implementation of an FIR followed by a 16-state MLSE can enable the 100-m transmission below the 7% hard decision (HD) forward error correction (FEC) threshold limit and outperforms its other two counterparts for the back-to-back case as well as after 100-m transmission for the high-bandwidth transmitter implementation. On the other hand, lower bandwidth DAC implementations, i.e., 15 GHz, require an increased state MLSE without the need for a preceding FIR filter to bring the bit error rate (BER) below the HD-FEC limit after 100-m OM4 fiber transmission. DSP complexity versus BER performance is assessed for all the aforementioned scenarios evaluating the impact of the transmitter's bandwidth on the overall system's performance. Our proposed solutions show that 112 Gb/s 100-m OM4 multimode links based on VCSELs and standard OM4 fiber can enable next generation 100 and 400 Gb/s wavelength division multiplexed optical interconnects.

[1]  Enbo Zhou,et al.  112-Gb/s duobinary 4-PAM transmission over 200-m multi-mode fibre , 2015, 2015 European Conference on Optical Communication (ECOC).

[2]  Milton Feng,et al.  850 nm Oxide-VCSEL With Low Relative Intensity Noise and 40 Gb/s Error Free Data Transmission , 2014, IEEE Photonics Technology Letters.

[3]  Stephen E. Ralph,et al.  Requirements and results for practical VCSEL transmission using PAM-4 over MMF , 2016, 2016 Optical Fiber Communications Conference and Exhibition (OFC).

[4]  Peter A. Andrekson,et al.  70 Gbps 4-PAM and 56 Gbps 8-PAM Using an 850 nm VCSEL , 2014, Journal of Lightwave Technology.

[5]  J. Conradi,et al.  Multilevel signaling for increasing the reach of 10 Gb/s lightwave systems , 1999 .

[6]  107.5 Gb/s 850 nm multi- and single-mode VCSEL transmission over 10 and 100 m of multi-mode fiber , 2016, 2016 Optical Fiber Communications Conference and Exhibition (OFC).

[7]  A. Lender Correlative Digital Communication Techniques , 1964 .

[8]  J.-R. Kropp,et al.  Accelerated aging of 28 Gb s−1 850 nm vertical-cavity surface-emitting laser with multiple thick oxide apertures , 2015 .

[9]  S. Nelson,et al.  SWDM strategies to extend performance of VCSELs over MMF , 2016, 2016 Optical Fiber Communications Conference and Exhibition (OFC).

[10]  C. Schulien,et al.  Digital equalisation at 10.7Gb/s using maximum likelihood sequence estimation- a present and future technology , 2005 .

[11]  Nevio Benvenuto,et al.  Algorithms for Communications Systems and their Applications , 2021 .

[12]  Ming C. Wu,et al.  Silicon oxide-planarized single-mode 850-nm VCSELs with TO package for 10 Gb/s data transmission , 2005 .

[13]  Nevio Benvenuto,et al.  Channel Equalization and Symbol Detection , 2003 .

[14]  Stanley J. Simmons,et al.  Sorting-based VLSI architectures for the M-algorithm and T-algorithm trellis decoders , 1995, IEEE Trans. Commun..

[15]  Changsong Xie,et al.  Modified Gardner phase detector for Nyquist coherent optical transmission systems , 2013, 2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC/NFOEC).

[16]  G. David Forney,et al.  Maximum-likelihood sequence estimation of digital sequences in the presence of intersymbol interference , 1972, IEEE Trans. Inf. Theory.

[17]  K. Suzuki,et al.  4 $\times$ 10 Gb/s WDM Transmission Over a 5-km-Long Photonic Crystal Fiber in the 800-nm Region , 2007, IEEE Photonics Technology Letters.

[18]  Wei Chen,et al.  140-Gb/s 20-km Transmission of PAM-4 Signal at 1.3 $\mu \text{m}$ for Short Reach Communications , 2015, IEEE Photonics Technology Letters.

[19]  James A. Lott,et al.  Arrays of 850 nm photodiodes and vertical cavity surface emitting lasers for 25 to 40 Gbit/s optical interconnects , 2012 .

[20]  R. Lingle,et al.  51.56 Gb/s SWDM PAM4 transmission over next generation wide band multimode optical fiber , 2016, 2016 Optical Fiber Communications Conference and Exhibition (OFC).