O-band QKD link over a multiple ONT loaded carrier-grade GPON for FTTH applications.

We have successfully demonstrated the integration of a commercial O-band Quantum Key Distribution (QKD) system over a testbed that replicates a carrier-grade Fiber-to-the-Home (FTTH) optical access network consisting of components and systems installed in real-life FTTH operational deployments. The experiment demonstrated a QKD transmission over a 1:16 user Gigabit Optical Passive Network (GPON) configuration featuring a total of 9 Optical Network Terminals (ONTs) at the premises of the Telecom Operator COSMOTE that followed the operator's standard FTTH divided in two splitting stages. The architecture we implemented was a downstream access network with the quantum transmitter located at the operator's Central Office (CO) and the quantum receiver located on the end user's side.

Photonic Integrated Circuit Based Temperature Sensor forOut-of-Autoclave Composite Parts Production Monitoring.

The use of composite materials has seen widespread adoption in modern aerospace industry. This has been facilitated due to their favourable mechanical characteristics, namely, low weight and high stiffness and strength. For broader implementation of those materials though, the out-of-autoclave production processes have to be optimized, to allow for higher reliability of the parts produced as well as cost reduction and improved production speed.

A Miniature Bio-Photonics Companion Diagnostics Platform for Reliable Cancer Treatment Monitoring in Blood Fluids.

In this paper, we present the development of a photonic biosensor device for cancer treatment monitoring as a complementary diagnostics tool. The proposed device combines multidisciplinary concepts from the photonic, nano-biochemical, micro-fluidic and reader/packaging platforms aiming to overcome limitations related to detection reliability, sensitivity, specificity, compactness and cost issues. The photonic sensor is based on an array of six asymmetric Mach Zender Interferometer (aMZI) waveguides on silicon nitride substrates and the sensing is performed by measuring the phase shift of the output signal, caused by the binding of the analyte on the functionalized aMZI surface.

High performance refractive index sensor based on low Q-factor ring resonators and FFT processing of wavelength scanning data.

We extend our previous simulation study and we present experimental results regarding our Fast Fourier Transform method for the calculation of the resonance shifts in biosensors based on micro-ring resonators (MRRs). For the simulation study, we use a system model with a tunable laser at 850 nm, an MRR with 1.5∙10 quality factor, and a detection system with 50 dB maximum signal-to-noise ratio, and investigate the impact on the system performance of factors like the number of the resonance peaks inside the scanning window, the wavelength dependence of the laser power, and the asymmetry of the transfer functions of the MRRs.

New set of design rules for resonant refractive index sensors enabled by FFT based processing of the measurement data.

It is still a common belief that ultra-high quality-factors (Q-factors) are a prerequisite in optical resonant cavities for high refractive index resolution and low detection limit in biosensing applications. In combination with the ultra-short steps that are necessary when the measurement of the resonance shift relies on the wavelength scanning of a laser source and conventional methods for data processing, the high Q-factor requirement makes these biosensors extremely impractical. In this work we analyze an alternative processing method based on the fast-Fourier transform, and show through Monte-Carlo simulations that improvement by 2-3 orders of magnitude can be achieved in the resolution and the detection limit of the system in the presence of amplitude and spectral noise.

High-gain 1.3 μm GaInNAs semiconductor optical amplifier with enhanced temperature stability for all-optical signal processing at 10 Gb/s.

We report on the complete experimental evaluation of a GaInNAs/GaAs (dilute nitride) semiconductor optical amplifier that operates at 1.3 μm and exhibits 28 dB gain and a gain recovery time of 100 ps. Successful wavelength conversion operation is demonstrated using pseudorandom bit sequence 2-1 non-return-to-zero bit streams at 5 and 10  Gb/s, yielding error-free performance and showing feasibility for implementation in various signal processing functionalities.

Bandpass sampling in heterodyne receivers for coherent optical access networks.

A novel digital receiver architecture for coherent heterodyne-detected optical signals is presented. It demonstrates the application of bandpass sampling in an optical communications context, to overcome the high sampling rate requirement of conventional receivers (more than twice the signal bandwidth). The concept is targeted for WDM coherent optical access networks, where applying heterodyne detection constitutes a promising approach to reducing optical hardware complexity.

Complex monolithic and InP hybrid integration on high bandwidth electro-optic polymer platform.

We report on the monolithic integration of multimode interference couplers, Bragg gratings, and delay-line interferometers on an electro-optic polymer platform capable of modulation directly at 100 Gb/s. We also report on the hybrid integration of InP active components with the polymer structure using the butt-coupling technique. Combining the passive and the active components, we demonstrate a polymer-based, external cavity laser with 17 nm tuning range and the optical assembly of an integrated 100 Gb/s transmitter, and we reveal the potential of the electro-optic polymer technology to provide the next generation integration platform for complex, ultra-high-speed optical transceivers.

Serial 100 Gb/s connectivity based on polymer photonics and InP-DHBT electronics.

We demonstrate the first integrated transmitter for serial 100 Gb/s NRZ-OOK modulation in datacom and telecom applications. The transmitter relies on the use of an electro-optic polymer modulator and the hybrid integration of an InP laser diode and InP-DHBT electronics with the polymer board. Evaluation is made at 80 and 100 Gb/s through eye-diagrams and BER measurements using a receiver module that integrates a pin-photodiode and an electrical 1:2 demultiplexer.

Quaternary TDM-PAM as upgrade path of access PON beyond 10Gb/s.

A 20 Gb/s quaternary TDM-PAM passive optical network with chirped and non-linear optical transmitters is experimentally demonstrated. The migration from legacy TDM-PONs and the implications of using available 10 Gb/s components are analyzed. We show that a loss budget of 27.

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.

0.48Tb/s (12x40Gb/s) WDM transmission and high-quality thermo-optic switching in dielectric loaded plasmonics.

We demonstrate Wavelength Division Multiplexed (WDM)-enabled transmission of 480Gb/s aggregate data traffic (12x40Gb/s) as well as high-quality 1x2 thermo-optic tuning in Dielectric-Loaded Surface Plasmon Polariton Waveguides (DLSPPWs). The WDM transmission characteristics have been verified through BER measurements by exploiting the heterointegration of a 60 μm-long straight DLSPPW on a Silicon-on-Insulator waveguide platform, showing error-free performance for six out of the twelve channels. High-quality thermo-optic tuning has been achieved by utilizing Cycloaliphatic-Acrylate-Polymer as an efficient thermo-optic polymer loading employed in a dual-resonator DLSPPW switching structure, yielding a 9 nm wavelength shift and extinction ratio values higher than 10 dB at both output ports when heated to 90°C.

Fabrication and experimental demonstration of the first 160 Gb/s hybrid silicon-on-insulator integrated all-optical wavelength converter.

We present a hybrid integrated photonic circuit on a silicon-on-insulator substrate that performs ultra high-speed all-optical wavelength conversion. The chip incorporates a 1.25 mm non-linear SOA mounted on the SOI board using gold-tin bumps as small as 14 μm.

Multi-format all-optical processing based on a large-scale, hybridly integrated photonic circuit.

We investigate through numerical studies and experiments the performance of a large scale, silica-on-silicon photonic integrated circuit for multi-format regeneration and wavelength-conversion. The circuit encompasses a monolithically integrated array of four SOAs inside two parallel Mach-Zehnder structures, four delay interferometers and a large number of silica waveguides and couplers. Exploiting phase-incoherent techniques, the circuit is capable of processing OOK signals at variable bit rates, DPSK signals at 22 or 44 Gb/s and DQPSK signals at 44 Gbaud.

20-GHz broadly tunable and stable mode-locked semiconductor amplifier fiber ring laser.

We present an actively mode-locked fiber ring laser that uses a single active semiconductor optical amplifier device to provide both gain and gain modulation from an external optical pulse train. The laser source generated 4.3-ps pulses at 20 GHz over a 16-nm tuning range and is stable against environmental changes and simple to build.

Optical clock repetition-rate multiplier for high-speed digital optical logic circuits.

Repetition-rate multiplication has been shown by use of a fiber ring oscillator with a semiconductor optical amplifier as the gain medium and by use of fast saturation and recovery of the amplifier from an external optical pulse train. Repetition-frequency multiplication up to 6 times and up to 34.68-GHz frequency have been achieved.

Packet clock recovery using a bismuth oxide fiber-based optical power limiter.

We demonstrate an optical clock recovery circuit that extracts the line rate component on a per packet basis from short data packets at 40Gb/s. The circuit comprises a Fabry-Perot filter followed by a novel power limiting configuration, which in turn consists of a 5m highly nonlinear bismuth oxide fiber in cascade with an optical bandpass filter. Both experimental and simulation-based results are in close agreement and reveal that the proposed circuit acquires the timing information within only a small number of bits, yielding a packet clock for every respective data packet.

40 Gb/s 2R Burst Mode Receiver with a single integrated SOA-MZI switch.

We demonstrate a novel scheme for 2R burst mode reception capable of operating error-free with 40 Gb/s variable length, asynchronous optical data packets that exhibit up to 9 dB packet-to-packet power variation. It consists of a single, hybrid integrated, SOA-based Mach-Zehnder Interferometer (SOA-MZI) with unequal splitting ratio couplers, configured to operate as a self-switch. We analyze theoretically the power equalization properties of unequal splitting ratio SOA-MZI switches and show good agreement between theory and experiment.

Packet-level synchronization scheme for optical packet switched network nodes.

We demonstrate an all-optical, self-synchronization scheme for optical packet switched network nodes. It provides both the packet clock signal and the packet beginning, marker pulse. The circuit uses two hybridly integrated MZI switches and has been evaluated with synchronous, asynchronous and variable length, data packets at 10 Gb/s.

Compact all-optical packet clock and data recovery circuit using generic integrated MZI switches.

We present and evaluate a compact, all-optical Clock and Data Recovery (CDR) circuit based on integrated Mach Zehnder interferometric switches. Successful operation for short packet-mode traffic of variable length and phase alignment is demonstrated. The acquired clock signal rises within 2 bits and decays within 15 bits, irrespective of packet length and phase.

40 Gb/s all-optical packet clock recovery with ultrafast lock-in time and low inter-packet guardbands.

We demonstrate a 40 Gb/s self-synchronizing, all-optical packet clock recovery circuit designed for efficient packet-mode traffic. The circuit locks instantaneously and enables sub-nanosecond packet spacing due to thelow clock persistence time. A low-Q Fabry-Perot filter is used as a passive resonator tuned to the line-rate that generates a retimed clock-resembling signal.

Generation of 40-GHz control signals from flag pulses for switching all-optical gates for use with optical packets.

We demonstrate an all-optical circuit capable of generating 40-GHz control signals from flag pulses that can be used to define the switching state of all-optical gates for use with optical packets. The circuit comprises a Fabry-Perot filter and a semiconductor optical amplifier, and with a single pulse it can generate 12 control pulses with 0.64-dB amplitude modulation.

Sagnac fiber logic gates and their possible applications: a system perspective.

The Sagnac all-optical fiber logic gate functions as a two-input AND gate, a two-input AND gate with one inverting input, or both. The fiber logic gate is pipelined and has a fixed latency. This latency has no effect on feed-forward combinatoric circuits.

Addressable fiber-loop memory.

Optical bits are selectively and nondestructively read out of an all-optical recirculating fiber-loop memory by using a synchronized probe signal at a second wavelength.