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UNLOC continues strong presence at OFC, the world’s largest fibre communications conference

13 March, 2017

Since the start of the UNLOC programme, UNLOC members have contributed to 34 papers presented at OFC. Our contribution to OFC 2017 is no exception, with another 10 papers involving UNLOC members.

OFC is a highlight in the optical communications calendar as leading researchers gather to share the latest progress towards next-generation optical communications. This year marks the 42nd year of OFC.

UNLOC OFC highlights

Realising superfast data rates

Dr Lidia Galdino, Dr Robert Maher, PhD students Gabriel Saavedra, Daniel Elson and others UNLOC members have worked with Dr David Millar (Mitsubishi Electric Research Laboratories) and colleagues to achieve dual-carrier 1Tb/s transmission using a transceiver suitable for implementation in commercial systems. UNLOC broke the record for data rate at this speed in early 2016; however, this latest work takes the next step by reducing complexity to make such systems economically viable. Realising these next-generation communication systems is key if we are to outpace the growing demand for data.

Reducing complexity to speed up inter-city data connections

UCL Optical Networks Group PhD student, Zhe Li, in collaboration with supervisor Dr Robert Killey, will present two papers with new techniques to improve data transfer at the metro (intra- and inter-city) network scales. Zhe proposes a new technique which will allow 100Gb/s transmission in a single channel over a record distance of 240km - triple the distance current commercial systems achieve, and with low complexity and cost.

Zhe’s second presentation builds on this by testing the effectiveness of a number of digital signal processing techniques in real-world networks. In traditional direct-detection systems, nonlinearity compensation techniques can currently only be applied at the transmitter. This means that when data is sent from one city to multiple destinations, feedback information must be sent from the receiver back to the transmitter, complicating the process. A new compensation technique greatly lowers the complexity and can be applied at the receiver, reducing cost.

Working towards ultra-wide bandwidths

One of the next steps to optimise the capacity of optical communications is to transmit signals over ultra-wide bandwidths. UCL Optical Networks Group PhD student, Gabriel Saavedra Mondaca’s paper will explain how capacity-limiting nonlinearities in optical fibre grow as bandwidth increases. Gabriel’s results match the models for transmitted bandwidth up to 7.3THz, the state-of-the-art for current amplifier technology. The results show that increasing bandwidth increases the nonlinearity of the signal, but that the resulting penalties decrease with larger increases in bandwidth. So using ultra-wide bandwidths in next-generation systems will not cause significant penalties.

Ultra-wide bandwidth transmissions require ultra-broadband lasers. Prof Sergei Turitsyn has collaborated with other Aston University colleagues on just this issue. Their study targets the implementation of an ultra-broadband laser amplifier that could be used for telecom applications and widely tunable lasers. The members of UNLOC team presented a Raman fibre laser with the record tunability of more than 200 nm in the range of 1400-1622 nm with 29-nm gap exploiting only one Raman cascade. Such a demonstration represents a significant advance in the area of tunable fibre lasers, and paves the way towards various new applications, e.g. ultrabroadband amplifiers.

Overcoming fundamental limits of optical fibre transmission

Polarization mode dispersion (PMD) is the random rotation of light polarization in fibre and is one of the fundamental limits in data transfer. UCL Optical Networks Group PhD student, Gabriele Liga, has worked with Cristian Czegledi and other colleagues from Chalmers University of Technology, as well as other UNLOC researchers, to develop an improved digital signal processing algorithm to help account for PMD. This technique results in a 1db gain, a 25% improvement, in the optimum signal to noise ratio (SNR). This work will influence receiver design in next-generation inter-city systems, long-haul links and beyond.

Full list of presentations

M3C.4 - On the Impact of Probabilistic Shaping on SNR and Information Rates in Multi-Span WDM Systems
T. Fehenberger, A. Alvarado, G. Böcherer, and N. Hanik

M3D.2 - A Simplified Dual-Carrier DP-64QAM 1 Tb/s Transceiver 
D.S. Millar, L. Galdino, R. Maher, M. Pajovic, T. Koike-Akino, G. Saavedra, D.J. Elson, D. Lavery, K. Shi, M.S. Erkılınç, E. Sillekens, R.I. Killey, B.C. Thomsen, K. Kojima, K. Parsons, P. Bayvel

M3D.3 - 246 GHz Digitally Stitched Coherent Receiver 
K. Shi, E. Sillekens and B.C. Thomsen

Tu3I.4 - 112 Gb/s/λ WDM Direct-Detection Nyquist-SCM Transmission at 3.15 (b/s)/Hz Over 240 km SSMF Enabled by Novel Beating Interference Compensation 
Z. Li, M.S. Erkılınç, K. Shi, E. Sillekens, L. Galdino, B.C. Thomsen, P. Bayvel, and R.I. Killey

W1F.3 - Ultra-Broadband Tunable Fiber Laser 
V.V. Dvoyrin, N. Tarasov, and S.K. Turitsyn

W1G.1 - Experimental Investigation of Nonlinear Signal Distortions in Ultra-Wideband Transmission Systems
G. Saavedra, M. Tan, D.J. Elson, L. Galdino, D. Semrau, Md. A. Iqbal, I.D. Phillips, P. Harper, N. Mac Suibhne, A. D. Ellis, D. Lavery, B. C. Thomsen, R. I. Killey, and P. Bayvel

W1G.6 - Modified Digital Backpropagation Accounting for Polarization-Mode Dispersion
C.B. Czegledi, G. Liga, D. Lavery, M. Karlsson, E. Agrell, S.J. Savory, and P. Bayvel

Th2A.54 - Spectral efficiency estimation in periodic nonlinear Fourier transform based communication systems
M. Kamalian, J.E. Prilepsky, S.T. Le, and S.K. Turitsyn

Th3D.2 - Performance Improvement of Electronic Dispersion Post-Compensation in Direct Detection Systems Using DSP-Based Receiver Linearization 
Z. Li, M.S. Erkılınç, K. Shi, E. Sillekens, L. Galdino, B.C. Thomsen, P. Bayvel, and R.I. Killey

Th4C.4 - Achievable Information Rates of Square MQAM Modulation Formats after Carrier Phase Estimation 
M. Paskov, D. Lavery, A. Alvarado and P. Bayvel