Dimitrios Apostolopoulos

Optical Static RAM Cell

We demonstrate an optical static random access memory cell that provides read and write functionality at 5 Gb/s. The circuit comprises a hybridly integrated semiconductor optical amplifier-Mach-Zehnder interferometer (SOA-MZI) flip-flop serving as the memory unit and two additional SOA-based cross-gain modulation switches for controlling access to the memory cell.

Active plasmonics in WDM traffic switching applications

With metal stripes being intrinsic components of plasmonic waveguides, plasmonics provides a “naturally” energy-efficient platform for merging broadband optical links with intelligent electronic processing, instigating a great promise for low-power and small-footprint active functional circuitry. The first active Dielectric-Loaded Surface Plasmon Polariton (DLSPP) thermo-optic (TO) switches with successful performance in single-channel 10 Gb/s data traffic environments have led the inroad towards bringing low-power active plasmonics in practical traffic applications. In this article, we introduce active plasmonics into Wavelength Division Multiplexed (WDM) switching applications, using the smallest TO DLSPP-based Mach-Zehnder interferometric switch reported so far and showing its successful performance in 4×10 Gb/s low-power and fast switching operation. The demonstration of the WDM-enabling characteristics of active plasmonic circuits with an ultra-low power × response time product represents a crucial milestone in the development of active plasmonics towards real telecom and datacom applications, where low-energy and fast TO operation with small-size circuitry is targeted.

Interfacing Dielectric-Loaded Plasmonic and Silicon Photonic Waveguides: Theoretical Analysis and Experimental Demonstration

A comprehensive theoretical analysis of end-fire coupling between dielectric-loaded surface plasmon polariton and rib/wire silicon-on-insulator (SOI) waveguides is presented. Simulations are based on the 3-D vector finite element method. The geometrical parameters of the interface are varied in order to identify the ones leading to optimum performance, i.e., maximum coupling efficiency. Fabrication tolerances about the optimum parameter values are also assessed. In addition, the effect of a longitudinal metallic stripe gap on coupling efficiency is quantified, since such gaps have been observed in fabricated structures. Finally, theoretical results are compared against insertion loss measurements, carried out for two distinct sets of samples comprising rib and wire SOI waveguides, respectively.

Data Transmission and Thermo-Optic Tuning Performance of Dielectric-Loaded Plasmonic Structures Hetero-Integrated on a Silicon Chip

We demonstrate experimental evidence of the data capture and the low-energy thermo-optic tuning credentials of dielectric-loaded plasmonic structures integrated on a silicon chip. We show 7-nm thermo-optical tuning of a plasmonic racetrack-resonator with less than 3.3 mW required electrical power and verify error-free 10-Gb/s transmission through a 60-μm-long dielectric-loaded plasmonic waveguide.

Enabling Tb/s Photonic Routing: Development of Advanced Hybrid Integrated Photonic Devices to Realize High-Speed, All-Optical Packet Switching

We present recent advances in photonic integration introduced by integration-related European research project IST-MUFINS. The contribution of the project in the progress of a functional photonic integration is outlined, from device fabrication to device application focusing on photonic routing using multielement photonic chips. Specifically, we report on the transition from single-element to multielement photonic devices with the fabrication of hybrid integrated arrays of optical switches exploiting and upgrading the silica-on-silicon hybrid photonic integration. We demonstrate how the enhanced processing power and capacity of these components can be exploited to implement key functionalities required in next-generation fully integrated terabits per second photonic routers.

40 Gb/s NRZ Wavelength Conversion Using a Differentially-Biased SOA-MZI: Theory and Experiment

We present theoretical and experimental performance analysis of 40 Gb/s Non-Return-to-Zero (NRZ) All-Optical Wavelength Conversion (AOWC) using a differentially-biased SOA-MZI. A frequency domain transfer function model for both the standard single-control SOA-MZI-based AOWC and for the differentially-biased SOA-MZI is analytically derived, exploiting first order perturbation theory techniques and showing that only the differentially-biased scheme can yield an almost flat low-pass filtering response enabling wavelength conversion at 40 Gb/s. The theoretically obtained results are also confirmed through experiments that demonstrate successful 40 Gb/s AOWC functionality for NRZ data signals only when a differentially-biased SOA-MZI configuration is employed, whereas an error-floor is obtained when 40 Gb/s NRZ AOWC with the standard single-control SOA-MZI scheme is attempted. The 1.7 dB negative power penalty obtained by the differentially-biased SOA-MZI architecture confirms its enhanced regenerative properties and its potential for extending 40 Gb/s optical transparent network dimensions by means of cascaded 2R AOWC stages.

A 40 Gb/s 3R Burst Mode Receiver with 4 integrated MZI switches

We demonstrate for the first time a 40 Gb/s all-optical 3R burst-mode receiver error-free operation for 9,3 dB power fluctuation between short bursty packets. It consists of a sequence of four integrated MZI switches.

An SOA-MZI NRZ Wavelength Conversion Scheme With Enhanced 2R Regeneration Characteristics

We present a novel scheme for all-optical nonreturn-to-zero (NRZ) wavelength conversion with enhanced 2R regenerative characteristics. It employs a hybridly integrated semiconductor optical amplifier Mach-Zehnder interferometer using bidirectional data injection and an additional external continuous-wave signal for differentially biasing the interferometer arms, optimizing gain and phase conditions during the switching functionality. Experimental verification of its superior 2R regenerative capabilities are demonstrated for 10-Gb/s NRZ data signals.

All-Optical T-Flip-Flop Using a Single SOA-MZI-Based Latching Element

The authors demonstrate a novel all-optical T-flip-flop (TFF) layout utilizing a single optical latching element that comprises an integrated semiconductor optical amplifier and Mach-Zehnder inteferometer and a feedback loop. Experimental proof-of-concept verification is presented at 8 Mb/s using off-the-shelf bulk components and a fiber-based feedback implementation. The proposed TFF architecture requires the minimum number of active components and just a single toggling signal as input. Its simple circuit design is amenable with photonic integration and holds the credentials for operation at multi-Gb/s speeds.

Active Plasmonics in True Data Traffic Applications: Thermo-Optic On/Off Gating Using a Silicon-Plasmonic Asymmetric Mach–Zehnder Interferometer

We present the first system-level demonstration of an active plasmonic device in 10-Gb/s data traffic conditions. An asymmetric silicon-plasmonic Mach-Zehnder interferometer with dielectric-loaded plasmonic waveguides serving as the electrically controlled arms, operates as thermo-optic On/Off gating element with 2.8- μ s response time and 10.8-mW power consumption.