Nikos Iliadis

A 64 Gb/s PAM-4 linear optical receiver

We present a linear optical receiver realized on 130 nm SiGe BiCMOS. Error-free operation assuming FEC is shown at bitrates up to 64 Gb/s (32 Gbaud) with 165mW power consumption, corresponding to 2.578 pJ/bit.

Bandwidth and Wavelength-Selective MUX/DEMUX Microresonator Elements for Flexible-Grid Applications

We propose a novel concept for a MUX/DEMUX array based on microresonators with reconfigurable bandwidth and wavelength response. Initial experimental results on a single MR element prove its suitability for flexible-grid applications.

Bringing High-Performance GaInNAsSb/GaAs SOAs to True Data Applications

We experimentally demonstrate the high-speed data processing capabilities of a GaInNAsSb semiconductor optical amplifier operating at 1.55 μm. The investigated structure exhibits good thermal characteristics and fast gain dynamics with 10%-90% recovery time of 55 ps. Successful wavelength conversion of 10-Gb/s signals is reported. A maximum power penalty of <;2.4 dB for return to zero formatting and of 1.9 dB for nonreturn to zero is demonstrated.

Photonic integration enabling new multiplexing concepts in optical board-to-board and rack-to-rack interconnects

New broadband applications are causing the datacenters to proliferate, raising the bar for higher interconnection speeds. So far, optical board-to-board and rack-to-rack interconnects relied primarily on low-cost commodity optical components assembled in a single package. Although this concept proved successful in the first generations of opticalinterconnect modules, scalability is a daunting issue as signaling rates extend beyond 25 Gb/s. In this paper we present our work towards the development of two technology platforms for migration beyond Infiniband enhanced data rate (EDR), introducing new concepts in board-to-board and rack-to-rack interconnects. The first platform is developed in the framework of MIRAGE European project and relies on proven VCSEL technology, exploiting the inherent cost, yield, reliability and power consumption advantages of VCSELs. Wavelength multiplexing, PAM-4 modulation and multi-core fiber (MCF) multiplexing are introduced by combining VCSELs with integrated Si and glass photonics as well as BiCMOS electronics. An in-plane MCF-to-SOI interface is demonstrated, allowing coupling from the MCF cores to 340x400 nm Si waveguides. Development of a low-power VCSEL driver with integrated feed-forward equalizer is reported, allowing PAM-4 modulation of a bandwidth-limited VCSEL beyond 25 Gbaud. The second platform, developed within the frames of the European project PHOXTROT, considers the use of modulation formats of increased complexity in the context of optical interconnects. Powered by the evolution of DSP technology and towards an integration path between inter and intra datacenter traffic, this platform investigates optical interconnection system concepts capable to support 16QAM 40GBd data traffic, exploiting the advancements of silicon and polymer technologies.

16×1 dual polarization SOI MUX/DEMUX for flexible-grid optical networks

We demonstrate a bandwidth selective and wavelength flexible 16×1 MUX/DEMUX device with on-chip polarization multiplexing functionality. Experimental demonstration on data traffic conditions revealed excellent performance for operation in Flex-Grid application scenarios.

1.55-μm Dilute Nitride SOAs with low temperature sensitivity for coolerless on-chip operation

The temperature dependence of GaAs and InP SOA materials is investigated experimentally in this work. The direct comparison study verified that Dilute Nitrides are less temperature sensitive showing enhanced thermal stability on ASE spectrum and gain measurements in CW mode. Wavelength Conversion experiment at 10 Gb/s verified that GaAs SOA keeps up with the fast gain dynamics and the proper data processing at elevated temperatures while the performance of InP material is drastically degraded by heating the SOA device.

High gain 1.3-μm GaInNAs SOA with fast-gain dynamics and enhanced temperature stability

Semiconductor optical amplifiers (SOAs) are a well-established solution of optical access networks. They could prove an enabling technology for DataCom by offering extended range of active optical functionalities. However, in such costand energy-critical applications, high-integration densities increase the operational temperatures and require powerhungry external cooling. Taking a step further towards improving the cost and energy effectiveness of active optical components, we report on the development of a GaInNAs/GaAs (dilute nitride) SOA operating at 1.3μm that exhibits a gain value of 28 dB and combined with excellent temperature stability owing to the large conduction band offset between GaInNAs quantum well and GaAs barrier. Moreover, the characterization results reveal almost no gain variation around the 1320 nm region for a temperature range from 20° to 50° C. The gain recovery time attained values as short as 100 ps, allowing implementation of various signal processing functionalities at 10 Gb/s. The combined parameters are very attractive for application in photonic integrated circuits requiring uncooled operation and thus minimizing power consumption. Moreover, as a result of the insensitivity to heating issues, a higher number of active elements can be integrated on chip-scale circuitry, allowing for higher integration densities and more complex optical on-chip functions. Such component could prove essential for next generation DataCom networks.

Optical PAM-4 generation through polarization multiplexing in single-polarization single-mode VCSELs

PAM-4 modulation is considered a key enabler for scaling capacity in datacenter networks, due to its bandwidth efficiency and implementation simplicity. We propose a novel technique for optical generation of four-level signals by means of polarization multiplexing, leveraging the single-polarization operation of a double-mesa single-mode VCSEL with 20.5 GHz 3-dB bandwidth. The scheme obviates the need for linear electronic drivers and circumvents the requirement for driving the VCSEL in its linear regime. Experimental results verify the scheme, exhibiting BER within FEC standards at 28 Gb/s. Comparison with an electrical PAM-4 modulated VCSEL demonstrates superior performance of the proposed concept.

Dilute Nitride SOAs for high-speed data processing in variable temperature conditions

We present the first experimental study of a Dilute Nitride SOA with high-speed gain dynamics and attractive thermal characteristics as a data processing element at 10Gb/s and at different operating temperatures.