The Ultra-high-speed optical communications (UHSOC) group conducts research on ways to increase the serial data rate in optical communication systems. This work involves all aspects from the physical layer with pulse compression and ultra-fast switching to network issues with development of essential network functionalities.  

The means to achieve ultra-high-speed serial data is to keep the bit rate upgrade in the optical domain, i.e. relying on optical time division multiplexing (OTDM) techniques, as sketched in Figure 1. In particular, we investigate the use of sub-ps pulses interleaved to 100’s Gigabit/s data streams for ultra-fast optical communications. More specifically, the group is currently working with the activities listed below.

Current activities:  

Ultra-fast functionalities for 640 Gbit/s and above:

• Optical switching
• Add/drop multiplexing
• Wavelength conversion
• Clock recovery and transmission
• Optical sampling techniques

All-optical switches based on:

• Functional fibres / highly non-linear fibres (HNLF) (from OFS Fitel Denmark, http://www.ofsoptics.dk/ )
• Semiconductor optical amplifiers (SOAs)
• Chalcogenide waveguides (As2S3) (from CUDOS Australia, http://www.cudos.org.au/ )
• Periodically poled Lithium Niobate (PPLN) (from NIMS Japan, www.nims.go.jp/ )

Pulse shaping:

• Pulse compression using various fibre-based techniques
• Flat-top pulse generation using
• • special filters (e.g. from ORC UK, http://www.orc.soton.ac.uk/ )
  • optical differentiation (du/dt = jw F(u)) with e.g. long-period fibre gratings (from the Academy of Sciences of the Czech Republic, http://www.ufe.cz/ )
  • optical Fourier transformation

Pulse sources:

• Using carbon nano-tubes (CNT) as saturable absorbers in modelocked fibre-based pulse sources
• Nano-structured photonic bandgap filters for synchronisation

Ultra-fast optical Ethernet

• 1 Tbit/s Ethernet issues

640Gbit/s

[Figure 2] Eye diagram of our generated 640 Gbit/s data signal

Track record of group /  some key results:  

• first ever C-band 640 Gbit/s wavelength conversion
• first ever 320 and 640 Gbit/s add/drop multiplexing
• second ever 640 Gbit/s clock recovery (first with PPLN)
• first in Europe to obtain error-free demultiplexing from 640 Gbit/s
• second ever to demonstrate full 640 Gbit/s transmission system

Links to stories in popular media:

http://ing.dk/artikel/85532   article

http://www.computerworld.dk/art/44707  article

http://www.bulletins-electroniques.com/actualites/54449.htm  article

http://www.fotonik.dtu.dk/upload/institutter/com/research/systems/download/640gbpswavelengthconversion_dtuavisen_20080204.pdf   article

http://www.abc.net.au/news/stories/2008/07/10/2299688.htm   article and radio interview (CUDOS)