EOS Experimental Platform for Optical OFDM Systems
Within the ADRENALINE testbed we have also implemented an experimental platform for optical OFDM systems (EOS). Specifically, the design of flexible, optical OFDM (O-OFDM) transmission schemes are studied and assessed. The experimental validation of the investigated modulation schemes based on multicarrier technology is enabled by our testbed equipment and it comprises two different parts. One is a photonic mesh network of 4 nodes with links of up to 150 km that is used to experimentally assess the different optical OFDM systems. The other one encompasses the different setups, including optical and optoelectronic systems and subsystems, for multicarrier modulation (either OFDM or DMT) transmission and reception based on offline processing.
On one hand, either an arbitrary waveform generator (up to 24 GSa/s and 9.6 GHz) or a high-speed digital to analog converter (up to 64 GSa/s and 13 GHz) provide an analog signal (from a digital one) to be modulated and transmitted on an optical link. On the other hand, with a real-time digital phosphor oscilloscope (up to 100 GSa/s, 20 GHz bandwidth) placed on the reception side, the resulting electrical signals after optical reception are acquired and further processed. Different digital signal processing (DSP) modules are available and can be conveniently designed for software-defined optical transmission.
Additionally, the EOS platform can be suitably configured by integrating several options of optical, electro-optical and electrical devices required to implement DSP-enabled sliceable bandwidth variable transponders (S-BVT). The multiple rate, multiple format, multiple reach, and multiple flow transmitters and receivers with sub and super-wavelength granularity can find application in different network segments, particularly for elastic optical networks and flexgrid technologies, possibly being SDN-enabled. Broadband interferometric modulators (Mach-Zehnder up to 40 GHz), based on different technologies (LiNbO3, GaAs) with the corresponding linear drivers are available to generate the optical signals from the analog electrical one. The platform is equipped with tunable laser sources with picometer resolution and several optical reception options, namely simple PIN photo-detection (capable to detect signals with bandwidth up to 50 GHz) or coherent reception front-end featuring phase diversity. In order to setup the desired transceiver/system configurations, other optical and electrical devices are available, including tunable optical filters with variable bandwidth and high power optical amplifiers.