PhD defence by Lau Frejstrup Suhr

Sensing and Transmission over Short Range Optical Links

Principal supervisor: Associate Professor Anders Clausen, DTU Fotonik
Co-supervisor: Professor Idelfonso Tafur Monroy, TU Eindhoven
Co-supervisor: Juan José Vegas Olmos, Mellanox Technologies 

Evaluation Board:
Associate Professor Darko Zibar, DTU Fotonik
Professor Joachim Oberhammer, KTH, Sweden
Professor Magnus Karlsson, Chalmers, Sweden

Master of the Ceremony:
Professor Karsten Rottwitt, DTU Fotonik

This thesis present three different applications for Intensity Modulated Direct Detection (IM/DD) fiber optical systems. The first part verifies that fiber optic can be used as a transparent means to extend the reach of two types of radars. These radars can be used to accurately track the breathing of human subjects which can help monitor the health of both patients and smart home residents.


The second part investigates the feasibility for high-speed intensity modulated transmission over 200-300 km standard single-mode fiber with wellknown equalizer techniques in the receiver to mitigate residual fiber impairments. This transmission length is an important range for inter data center connections that continue to need more and more bandwidth to support our highly connected world with ever increasing data center sizes. Furthermore, by extending IM/DD reach, intra data center communication could seamlessly be extended to connect data center to data center without remodulating the data, thereby reducing the complexity.


The third part investigates the performance of a 25 Gbps quasi coherent receiver (QCR) that utilizes Digital Signal Processing (DSP)-free coherent reception of Intensity Modulated (IM) signals. This receiver targets the next generation passive optical networks (PON)s that increases the bit rate from the previously standardized 10 Gbps. As the receiver has a bandwidth limitation feed forward and decision feedback equalizers are used to improve the signal quality, and thereby also enabling transmission over 20 km fiber links. PONs are becoming increasingly important with more households moving away from traditional TV to online streaming. Furthermore, PONs are expected to supply the link between base stations and the backbone in the future 5G mobile network. At the same time the PON components must be low cost in order to be competitive with other technologies, such as wireless or copper connections. Therefore, high speed, low cost receivers are needed to support the future PON expansion, where the QCR could be a promising technique.


Thu 01 Mar 18
13:30 - 16:30


Lyngby Campus
Bld. 308, aud. 11