Miguel Iglesias Olmedo

Time: Fri 2017-04-07 10.00 - 12.00

Lecturer: Miguel Iglesias Olmedo

Location: Sal "B", Electrum, Kistagången 16, Kista

Title: Impairment Mitigation in High Capacity and Cost-efficient Optical Data Links
Candidate: Miguel Iglesias Olmedo
Time: Friday April 7, 2017, at 10:00
Location: Sal "B", Electrum, Kistagången 16, Kista
Opponent: Prof. Marco Santagustina, University of Padova, Italy

Abstract:  The work presented in this thesis fits within the broader area of fiber optics communications. This is an important area of research as it provides a breeding ground for the present and future technologies supporting the Internet. Due to the ever-increasing bandwidth demands worldwide, the network infrastructures that make up the Internet are continuously being upgraded. This thesis aims to identify key segments of the Internet that are deemed to become the Internet’s bottleneck if new technology does not replace the current one. These are datacenter intra and inter-connects, and metropolitan core area networks. In each category, we provide a comprehensive overview of the state of the art, identify key impairments affecting data transmission, and suggest solutions to overcome them. For datacenter intra and inter-connects, the key impairments are lack of bandwidth from electro-optic devices, and dispersion. Solutions attempting to tackle these impairments must be constrained by cost and power consumption. The provided solution is MultiCAP, an alternative advance modulation format that is more tolerable to dispersion and provides bandwidth management features such as those found in more complex alternatives like discrete multitoned (DMT) modulation, while being flexible enough to sacrifice performance in order to gain simplicity. MultiCAP was the first advance modulation format to achieve over 100 Gb/s in 2013 for a data-center interconnect and set the world record on data transmission over a single vertical cavity surface-emitting laser (VCSEL) in 2014 for a short reach data link. In the case of metro-core networks, the challenge is to efficiently mitigate carrier induced frequency noise generated by monolithically integrated semiconductor lasers. By investigating semiconductor laser frequency noise profiles we show that carrier induced frequency noise plays an important role in system performance. We point out that, when such lasers are employed, the commonly used laser linewidth fails to estimate system performance, and we propose an alternative figure of merit we name "Effective Linewidth". We derive this figure of merit analytically, explore it by numerical simulations and experimentally validate our results by transmitting a 28 Gbaud DP-16QAM over an optical link. Our investigations cover the use of semiconductor lasers both in the transmitter side and as a local oscillator at the receiver. The obtained results show that our proposed effective linewidth is easy to measure and represents more accurately the amount of frequency noise, and hence the penalties associated to phase noise in the received signal.

2017-04-07T10:00 2017-04-07T12:00 Miguel Iglesias Olmedo Miguel Iglesias Olmedo
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