The Eindhoven University of Technology has a vacancy for a  

PhD student for Photonic integrated flexible WDM optical cross-connect nodes with on chip flow control for Petabit/s all-optical Data Center Networks 

in the Electro-Optical Communication Systems (ECO) group, Department of Electrical Engineering 

Work environment
Eindhoven University of Technology (https://www.tue.nl/en/) is one of Europe's top technological universities, situated at the heart of a most innovative high-tech region. Thanks to a wealth of collaborations with industry and academic institutes, our research has real-world impact. In 2015, TU/e was ranked 106th in the Times Higher Educational World University ranking and 49th in the Shanghai ARWU ranking (engineering). TU/e has around 3,000 employees and 2,300 PhD students (half of which international, representing about 70 nationalities).

The candidate will work at the Department of Electrical Engineering (https://www.tue.nl/en/university/departments/electrical-engineering/). Within the Department of Electrical Engineering at TU/e, research and education is done in the areas of Telecommunication, Signal processing, and energy transfer. The Interfaculty institute COBRA (Communication technology: Basic Research and Applications) as of 2017, which is now known as the Institute for Photonic Integration (IPI) performs research in the area of broadband telecommunication techniques, encompassing optical communication as well as radio communication. As a key member of IPI, the Electro-Optical Communication Systems (ECO) group focuses its research on optical communication system techniques, ranging from systems for ultra-high capacity long reach single mode transmission links, multi-mode and multi-core transmission systems, ultra-fast (all-) optical packet switching nodes, to multi-service flexible access and in-building networks.  ECO is has also participated in several national and international projects in the area of access, metro and core transmission networks, as well as data center networks. 

The COBRA Research Institute has recently won a prestigious NWO Zwaartekracht research grant for interdisciplinary research into integrated photonics, including research into novel photonic materials, devices and systems. The PhD student will participate in this research program and will collaborate intensely with the Photonic Integration group, also part of the COBRA Research Institute. The aim of his/her PhD research project is to investigate novel photonic integrated circuit concepts for elastic WDM optical cross-connect nodes with on chip flow control for Petabit/s all-optical Data Center Networks. 

Research challenges
One of the most challenging issues when upscaling a data centre is the network infrastructure which provides interconnection and aggregation of the servers. The overall network capacity of the data centre network (DCN) is expected to increase by a factor 1000 per decade, , growing into the multi Petabit/s range. This poses a number of critical technical challenges in terms of power consumption, connectivity, bandwidth density, and end-to-end latency (many applications impose harsh requirements < 1 microsecond). Next-generation DCNs based on high capacity optical cross-connects switches (OXCs) capable to switch high speed packets transparently in the optical domain can overcome those challenges. The transparency to data-rate and data-format eliminates massive optical-electronic-optical conversions, while the high capacity helps to flatten the network topology in order to avoid bandwidth bottlenecks and large latency caused by hierarchical architectures. Additionally, statistical time and wavelength multiplexing can provide high-degree connectivity, flexibility, and programmability. Despite the multiple advantages of fast OXCs, there are still several challenges to be solved both at the device level (material, design, and fabrication) and at the system level (photonic integration of scalable OXC architecture with fast and efficient nanoseconds control of the switch and network synchronization). Fast control of the OXCs remains one of the main challenges. To fully exploit the nanoseconds operation of the OXC, an efficient and fast optical control system that provides the routing information to the optical switches should be implemented. Critical functionalities for realizing an efficient optical control system are the optical flow control, synchronization and clock distribution between the OXCs and the large amount of edge nodes. 

In this research project, the PhD candidate will design, fabricate, and experimentally assess an innovative flexible photonic integrated WDM OXCs with on chip optical fast flow control interfaces, synchronization, and clock distribution. Innovative broadband switching elements with low drive control voltage (ideally controlled directly from the FPGA) will be investigate to minimize the overall power consumption and simplify the control interfaces. The work comprises analytical, simulation and experimental activities. The student will be working in close collaboration with leading researchers from the ECO, PhI, and PSN groups as well as experts from the NanoLab@TU/e cleanroom.

Candidates for this challenging project must have a Master of Science degree in Electrical Engineering or in Applied Physics, with a strong affinity with optical communication techniques and/or for photonic devices and circuits. He/she must be familiar with optical and electronic laboratory measurement equipment, optical fiber system and components, semiconductor devices, and electronic circuits. Knowledge of integration technologies is appreciated. He/she must have good communication skills, must be fluent in English, both in speaking and in writing, and must have good team-working capabilities.

The appointment is for four years. As an employee of the university you will receive a competitive salary as well as excellent secondary benefits (holiday allowance, etc.). The research in this project must be concluded with the attainment of a PhD degree. A salary is offered starting at Euro 2222,-  per month (gross) in the first year and increasing up to Euro 2840,- per month (gross) in the last year. Moreover 8% bonus share (holiday supplement) is provided annually. Assistance for finding accommodation can be given.