We are developing the first optical OFDM transceiver operating at 10 Gbit/s using real-time DSP.

Multicarrier modulation (MCM) schemes such as orthogonal frequency division multiplexing (OFDM) are being adopted for wireless applications (e.g. WiFi) and are attracting increasing attention for optical interconnects. Transmitting on N carriers simultaneously reduces the symbol rate to one Nth of the original symbol rate of the serial data, reducing the impact of fiber dispersion and other bandwidth limitations.

However, real-time digital signal processing (DSP) for OFDM at multi-gigabit/s data rates has not yet been developed or shown to be feasible. Our goal is to dbuild such a system that demonstrates a throughput > 10 Gbit/s.

The diagram shows the basic system. OFDM is a MCM scheme in which adjacent subcarriers are separated in frequency by 1/T, where T is the symbol period. The optical signal waveform is generated using an inverse fast Fourier transform (IFFT). Adjacent subcarriers overlap, but are orthogonal, and can be recovered at the receiver using FFT.

The bottleneck is the forward and inverse FFT. These FFTs are provided by the Spiral DFT IP generator.

This work is a collaboration between a research group at the University College London, Intel Lab Pittsburgh, and the CMU Spiral group. Specifically:

**UC London (EE)**- Rachid Bouziane
- Yannis Benlachtar
- Robert Killey

**Intel Lab Pittsburgh**- Madeleine Glick

**CMU (ECE)**- Christian Berger
- James Hoe
- Robert Koutsoyannis
- Peter Milder
- Markus Pueschel

- Yannis Benlachtar, Rachid Bouziane, Robert I. Killey, Christian Berger, Peter A. Milder, Robert Koutsoyannis, James C. Hoe, Markus Püschel and Madeleine Glick

**Optical OFDM for the Data Center**

submitted for publication - Rachid Bouziane, Peter A. Milder, Robert Koutsoyannis, Yannis Benlachtar, Christian Berger, James C. Hoe, Markus Püschel, Madeleine Glick and Robert I. Killey

**Design Studies for an ASIC Implementation of an Optical OFDM Transceiver**

to appear in Proc. European Conference on Optical Communication (ECOC), 2010 - Yannis Benlachtar, Philip M. Watts, Rachid Bouziane, Peter A. Milder, Robert Koutsoyannis, James C. Hoe, Markus Püschel, Madeleine Glick and Robert I. Killey

**Real-Time Digital Signal Processing for the Generation of Optical Orthogonal Frequency Division Multiplexed Signals**

to appear in IEEE Journal of Selected Topics in Quantum Electronics, 2010

- Yannis Benlachtar, Philip M. Watts, Rachid Bouziane, Peter A. Milder, Deepak Rangaraj, Anthony Cartolano, Robert Koutsoyannis, James C. Hoe, Markus Püschel, Madeleine Glick and Robert I. Killey
**Generation of Optical OFDM Signals Using 21.4 GS/s Real Time Digital Signal Processing**

Optics Express, Vol. 17, No. 20, pp. 17658-17668, 2009

- Yannis Benlachtar, Philip M. Watts, Rachid Bouziane, Peter A. Milder, Robert Koutsoyannis, James C. Hoe, Markus Püschel, Madeleine Glick and Robert I. Killey

**21.4 GS/s Real-Time DSP-Based Optical OFDM Signal Generation and Transmission Over 1600 km of Uncompensated Fibre**

Proc. European Conference on Optical Communication (ECOC), 2009