VPIphotonics

Berlin, Germany

VPIphotonics

Berlin, Germany
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Bilal S.M.,VPIphotonics | Goroshko K.,VPIphotonics | Louchet H.,VPIphotonics | Koltchanov I.,VPIphotonics | Richter A.,VPIphotonics
Optics InfoBase Conference Papers | Year: 2016

We demonstrate the effectiveness of digital nonlinear pre-compensation for Ramanamplified transmission of single-carrier 28 Gbaud PM-16QAM. Our simulation results show that by applying transmitter side digital backpropagation and carefully selecting forward and backward Raman pump powers, unrepeated transmission over 300 km can be achieved. © OSA 2016.


Bilal S.M.,VPIphotonics | Goroshko K.,VPIphotonics | Louchet H.,VPIphotonics | Koltchanov I.,VPIphotonics | Richter A.,VPIphotonics
Optical Fiber Technology | Year: 2017

In this work we investigate different nonlinearities compensation and mitigation techniques for an unrepeated Raman-amplified link over 420 km of ultra-low loss (ULL) optical fiber. For such long links (over 400 km) fiber nonlinearities become very significant as high forward pump power is needed to ensure sufficient optical-signal-to-noise-ratio (OSNR) to acquire a bit-error-rate (BER) not exceeding the forward-error-correction (FEC) threshold. Such nonlinearities will significantly limit the performance. Through numerical simulations, we show successful net 200 Gb/s single carrier and 1 Tb/s superchannel transmission using PM-QPSK and symbol-rate-optimization (SRO). First we implement single carrier 200 G transmission either using 28 Gbaud PM-16QAM or 56 Gbaud PM-QPSK. Nonlinearities are compensated by either using digital-back-propagation (DBP) or phase-conjugated twin waves (PCTWs). We compare the performance of DBP and PCTWs based single carrier 28 Gbaud PM-16QAM, at the same transmission distance and capacity, with single carrier PM-QPSK and find that PM-QPSK does not require any nonlinearity compensation to give better performance than 28 Gbaud PM-16QAM. Following this result, we show a successful unrepeated transmission of net 1 Tb/s PM-QPSK Nyquist-spaced superchannel with an intra-superchannel net spectral efficiency (SE) of ∼3.6 b/s/Hz, over 420 km of Raman amplified ULL fiber without using any nonlinearity compensation. To improve the performance of this superchannel we implement nonlinearity mitigation scheme based on SRO. We investigate 5 × 56 Gbaud, 10 × 28 Gbaud, 20 × 14 Gbaud and 40 × 7 Gbaud PM-QPSK channels and found that the best performance is shown by 20 × 14 Gbaud superchannel. For PM-16QAM, successful transmission is only possible either using DBP or PCTWs based transmission link. DBP has a very high computational complexity whereas PCTWs halves the overall link spectral efficiency. Even then both schemes do not outperform PM-QPSK for the same transmission distance and capacity. So for practical realization the nonlinearity robust modulation format PM-QPSK using SRO has been identified as the most promising approach for superchannel implementation of unrepeated Raman amplified links. © 2017


Goroshko K.,VPIphotonics | Louchet H.,VPIphotonics | Richter A.,VPIphotonics
Asia Communications and Photonics Conference, ACPC 2015 | Year: 2015

We investigate the PMD-induced penalty on digital back propagation by means of numerical simulations and show that its mean and standard deviation correlate with the accumulated link DGD. An analytical model supports our numerical results. © 2015 OSA.


Goroshko K.,VPIphotonics | Louchet H.,VPIphotonics | Richter A.,VPIphotonics
International Conference on Transparent Optical Networks | Year: 2016

In this paper, we investigate the impact of the stochastic nature of local fiber birefringence on nonlinear compensation techniques in non-dispersion managed transmission links. We describe the beneficial mechanism of a low-complex modification of the well-known digital back propagation (DBP) technique, which is based on single measurements of accumulated differential group delay (DGD) and principal states of polarization (PSP) at the receiver. Furthermore, we discuss limits of the DBP capability to increase spectral efficiency and reach distance, and compare exemplary application cases. © 2016 IEEE.


Louchet H.,VPIphotonics | Kuzmin K.G.,Development Center | Richter A.,VPIphotonics
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

The need for software-defined transmissions raises new challenges for the transceiver design: multiple modulation formats have to be supported to accommodate for varying bandwidth demand and physical characteristics of different optical paths. In order to keep the receiver complexity and cost low, most of the digital signal processing functionalities should be shared by the different formats. In this paper we address the problems of carrier frequency and phase recovery as well as the tracking of fast polarization rotations for arbitrary constellations in two or four dimensions. We first report how not only carrier frequency recovery but also ADC sampling error correction can be performed using a modulation-format independent frequency-domain approach. We then report a framework where the combined impact of phase error and fast polarization rotation can be described by a rotation in a four-dimensional space and show how to efficiently estimate and compensate this rotation. We finally investigate the dynamic performance of the reported algorithms for polarization-switched QPSK and 4D 32QAM constellations using numerical simulations. © 2014 Copyright SPIE.


Louchet H.,VPIphotonics | Richter A.,VPIphotonics
Asia Communications and Photonics Conference, ACP | Year: 2014

We show how the Importance Sampling method can be used to accurately estimate the bit-error-rate of coherent transmission systems including digital signal processing and forwarderror-correction under non-AWGN channel assumption. © 2014 OSA.


Andre N.S.,VPIphotonics | Habel K.,Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institut | Louchet H.,VPIphotonics | Richter A.,VPIphotonics
Optics Express | Year: 2013

We report experimental validations of an adaptive 2nd order Volterra equalization scheme for cost effective IMDD OFDM systems. This equalization scheme was applied to both uplink and downlink transmission. Downlink settings were optimized for maximum bitrate where we achieved 34Gb/s over 10km of SSMF using an EML with 10GHz bandwidth. For the uplink, maximum reach was optimized achieving 14Gb/s using a low-cost DML with 2.5GHz bandwidth. © 2013 Optical Society of America.


Andre N.S.,VPIphotonics | Louchet H.,VPIphotonics | Habel K.,Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institut | Richter A.,VPIphotonics
IEEE Photonics Technology Letters | Year: 2014

In multicarrier direct modulation direct detection systems, interaction between laser chirp and fiber group velocity dispersion induces subcarrier-to-subcarrier intermixing interferences (SSII) after detection. Such SSII become a major impairment in orthogonal frequency division multiplexing-based access systems, where a high modulation index, leading to large chirp, is required to maximize the system power budget. In this letter, we present and experimentally verify an analytical formulation to predict the level of signal and SSII and estimate the signal to noise ratio of each subcarrier, enabling improved bit-and-power loading and subcarrier attribution. The reported model is compact, and only requires the knowledge of basic link characteristics and laser parameters that can easily be measured. © 2014 IEEE.


Louchet H.,VPIphotonics | Kuzmin K.,Development Center | Richter A.,VPIphotonics
IEEE Photonics Technology Letters | Year: 2014

We introduce a framework where the combined impact of phase noise and fast polarization rotation can be described by a rotation in a four-dimensional space. Based on this outcome, we propose an equalization scheme performing joint carrier-phase and polarization rotation recovery that can be applied to arbitrary two- or four-dimensional signal constellations. After discussing practical implementation issues for this scheme, we show by means of numerical simulations that the performance of the proposed scheme is comparable with state-of-the-art equalization algorithms for the DP-QPSK, PS-QPSK, and 4D-32QAM modulation formats. © 1989-2012 IEEE.


Andre N.S.,VPIphotonics | Louchet H.,VPIphotonics | Filsinger V.,Siemens AG | Hansen E.,Siemens AG | Richter A.,VPIphotonics
Optics Express | Year: 2016

We compare OFDM and PAM for 400G Ethernet based on a 3-bit high baudrate IM/DD interface at 1550nm. We demonstrate 27Gb/s and 32Gb/s transmission over 10km SSMF using OFDM and PAM respectively. We show that capacity can be improved through adaptation/equalization to achieve 42Gb/s and 64Gb/s for OFDM and PAM respectively. Experimental results are used to create realistic simulations to extrapolate the performance of both modulation formats under varied conditions. For the considered interface we found that PAM has the best performance, OFDM is impaired by quantization noise. When the resolution limitation is relaxed, OFDM shows better performance. © 2016 Optical Society of America.

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