Hercules Avramopoulos

• Phd, MSc and BSc in Physics, Imperial College, London, UK
• Professor (Full) at National Technical University of Athens

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...

This paper presents an in-depth satellite-to-ground Quantum Key Distribution (QKD) feasibility analysis between a Low Earth Orbit (LEO) satellite and a 0.28 m small-sized Optical Ground Stations (OGSs) located in urban areas, over nighttime. Both Prepare & Measure (P&M) and Entanglement (ENT)- based QKD protocols are employed and compared in terms...

We demonstrate solid-state optical beam-steering utilizing polymer waveguides as edge emitters to form optical phased arrays (OPAs) for operation at 1550 nm. Waveguide spacing below the wavelength is hindered in low index contrast OPAs by cross-coupling, leading to the formation of unwanted grating lobes in the far field. We employ non-uniform spac...

We have successfully integrated an O-band commercial Quantum-Key-Distribution (QKD) system over a lit GPON testbed that replicates a carrier-grade Fiber-to-the-Home (FTTH) optical access network with multiple ONTs to emulate real-life FTTH operational deployments.

This paper presents a hybrid photonic integration concept based on the use of a polymer motherboard, InP EML arrays and InP PD arrays to realize WDM and SDM Terabit optical engines operating at 100-Gb/s or even at 200-Gb/s per lane. The optical engines are aligned with the Ethernet roadmap, are cost-efficient by design and can find their place in t...

Silicon Photonics enables the manufacturing of high-speed, low power integrated optical circuits with compact foot-prints, and recent studies have also shown it to have high tolerance to radiation. The technology has, therefore, been identified as an excellent candidate for the development of the next generation of radiation-tolerant optical links...

We demonstrate a compact heterodyne Laser Doppler Vibrometer (LDV) based on the realization of optical frequency shift in the silicon nitride photonic integration platform (TriPleX). We theoretically study, and experimentally evaluate two different photonic integrated optical frequency shifters (OFSs), utilizing serrodyne and single-sideband (SSB)...

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, high stiffness and strength. For broader implementation of those materials though, the out-of-autoclave production processes have to be optimized, to allow for hi...

This paper presents the end-to-end integration of a software defined network (SDN) reconfigurable real-time analog-intermediate frequency-over-fiber (A-IFoF)/millimeter wave (mmWave) layout into a real mobile network operator (MNO) infrastructure. The key part of the presented infrastructure is the fully programmable gateway array (FPGA)-based A-IF...

A novel O-band polarization splitter-rotator based on mode conversion and coupling is proposed. The device is broadband, tolerant to fabrication imperfections and compatible with DUV lithography MPW processes, requiring single-step etching. Simulations show TM0→TE0 efficiency greater than 89% across the O-band with peak value of 96.3%, and TE0-TE0...

Optoelectronic technology is expected to be the cornerstone of sub-THz communication systems, enabling access to and use of the vast frequency resources found in this portion of the spectrum. In this work we demonstrate a photonics-enabled sub-THz wireless link operating in real-time settings, using a PIN-PD-based THz emitter, and a THz receiver ba...

The current work presents the first experimental demonstration of real-time Ethernet (ETH) trial services and 4K-Ultra High Definition (UHD) video application transmission over a 2λ Wavelength Division Multiplexing (WDM) analog Fiber-Wireless (FiWi) mmWave X-haul network, supporting dynamic flexible capacity allocation through an integrated silicon...

Bit-pattern matching is an important technological capability, used in many fields such as network intrusion detection (NID) and packet classification systems. Essentially, it involves the matching of an input bit pattern to a bit-pattern entry of a memory structure inside the system. Contemporary methods focus on the decomposition of the input bit...

Photonic integrated circuits (PICs) are one of the key enablers for beyond 5G networks. A novel generation of fully integrated photonic-enabled transceivers operating seamlessly in W- D- and THz-bands is developed within the EU funded project TERAWAY. Photonic integration technology enables key photonic functionalities on a single PIC including pho...

In this paper, we present the development of a miniaturized Laser Doppler Vibrometer (LDV) system, based on the 3D hybrid integration of the Si3N4 platform of LioniX (TriPleX) and the polymer platform of Fraunhofer HHI (PolyBoard). The photonic integrated circuit (PIC) supports all the functionalities of an LDV system including the splitting of the...

We demonstrate a ball-lens based optical interface for coupling between a single mode fiber and a silicon grating coupler from the back side of a photonic integrated circuit (PIC). This allows compact packaging solutions and keeps the PIC top side accessible, e.g. for interacting with the environment in case of sensing applications. Different confi...

We propose a novel co-packaged optical transceiver architecture capable of operating at 112 Gbaud per lane and scalable to 1.6 Tb/s capacity and beyond for next generation 51.2T and 102.4T digital switches.

Coexistence of weak coherent pulses and intense light is experimentally demonstrated in a practical 5G X-haul scenario. Acceptable QBER measurements were obtained over 5 km fiber transmission by optimizing the parameters of single-photon sender/receiver stations.

We present a real-world Gigabit Passive Optical Network (GPON)-based Fiber to the Home (FTTH) network serving up to 32 users, installed in COSMOTE laboratories in Athens. The deployment relies on the use of fiber optics and GPON telecom equipment which are identical to those found in the currently deployed FTTH infrastructure. We describe real-life...

We propose an optical pre-equalizer which relaxes the need for power-hungry DSP in IM/DD applications. A reservoir computing-based approach is pursued demonstrating under FEC performance up to 6km at 50Gbaud NRZ outperforming digital FFE.

The immense growth of data traffic that traverses modern networks, calls for immediate solutions to tackle the challenges that arise in terms of speed, capacity, cost and energy efficiency. This manuscript outlines the key technological aspects of the PICaboo project, that aims to develop novel building blocks and Photonic Integrated Circuits (PICs...

We demonstrate the generation, of a mmWave signal via the injection of an optical frequency comb (OFC) into an integrated tunable dual distributed Bragg reflector (DBR) laser as well as the fiber transmission and the processing of this signal by an optical beamforming network (OBFN). The dual DBR laser is based on a hybrid indium phosphide (InP) –...

The 5G and beyond advancements will impact significantly the evolution of many vertical industries such as the Public Protection and Disaster Recovery (PPDR) sector. To this end, the requirements posed by PPDR operations and services can be satisfied to a certain great degree by 5G network capabilities associated with network slicing and incorporat...

The 5G and beyond advancements will impact significantly the evolution of many vertical industries such as the Surveillance and Safety sector. To this end, the requirements posed by its associated services can be satisfied to a certain degree by 5G network slicing and by control and user plane separation -allowing for exploitation of edge computing...

A novel thermally tunable polarization rotator based on mode hybridization, is presented. The proposed component features a compact device footprint of 15.5 μm, insertion loss of 2.25 dB, and PER value above 13 dB across the entire C-band. By exploiting a thermal tuning mechanism, PER higher than 30.5 dΒ over 15 nm range is achieved with 3.5 mW/nm...

The deployment of the new 5G system and ultra-broadband access networks, on one side, and the advent of network disaggregation and cloudification paradigms, on the other, are producing disruptive changes in metropolitan area networks (MANs). The new central offices will be more like small data centers than traditional Telco-type central offices. Th...

In future mobile networks, the evolution of optical transport architectures enabling the flexible, scalable interconnection of Baseband Units (BBUs) and Radio Units (RUs) with heterogeneous interfaces is a significant issue. In this paper, we propose a multi-technology hybrid transport architecture that comprises both analog and digital-Radio over...

Benes/Clos networks constitute a particularly important part of interconnection networks and have been used in numerous areas, such as multi-processor systems, data centers and on-chip networks. They have also attracted great interest in the field of optical communications due to the increasing popularity of optical switches based on these architec...

The first successful demonstration of real-time Ethernet trial services over an analog 2λ-WDM Fiber-Wireless mmWave X-haul is experimentally reported, controlled through Open Daylight SDN controller for flexibly allocating capacity via a low-loss Si 3 N 4 ROADM.

We demonstrate a dynamically reconfigurable optical switching node interconnecting both Digital and Analog RoF interfaces. Successful optical/wireless transmission is verified, and real-world services are showcased over the deployed WDM infrastructure. © 2022 The Author(s)

Quantum key distribution (QKD) has gained a lot of attention over the past few years, but the implementation of quantum security applications is still challenging to accomplish with the current technology. Towards a global-scale quantum-secured network, satellite communications seem to be a promising candidate to successfully support the quantum co...

We propose a novel concept for the implementation of 2-dimensional (2D) optical phased arrays (OPAs) with end-fire waveguides as antenna elements (AEs), and we present its theoretical model and experimental proof. The concept is based on the use of 3-dimensional (3D) photonic integrated circuits (PICs) with multiple waveguiding layers on the PolyBo...

We demonstrate a broadband and continuously tunable 14 optical beamforming network (OBFN), based on the hybrid integration of indium phosphide (InP) components in the silicon nitride (Si3N4) platform. The photonic integrated circuit (PIC) comprises a hybrid InP-Si3N4 external cavity laser, a pair of InP phase modulators, a Si3N4 optical single-side...

We propose a novel concept for the implementation of 2-dimensional (2D) optical phased arrays (OPAs) with end-fire waveguides as antenna elements (AEs), and we present its theoretical model and experimental proof. The concept is based on the use of 3-dimensional (3D) photonic integrated circuits (PICs) with multiple waveguiding layers on the PolyBo...

We propose a novel concept for the implementation of 2-dimensional (2D) optical phased arrays (OPAs) with end-fire waveguides as antenna elements (AEs), and we present its theoretical model and experimental proof. The concept is based on the use of 3-dimensional (3D) photonic integrated circuits (PICs) with multiple waveguiding layers on the PolyBo...

div>We demonstrate a broadband and continuously tunable 1×4 optical beamforming network (OBFN), based on the hybrid integration of indium phosphide (InP) components in the silicon nitride (Si3N4) platform. The photonic integrated circuit (PIC) comprises a hybrid InP-Si3N4 external cavity laser, a pair of InP phase modulators, a Si3N4 optical single...

div>We demonstrate a broadband and continuously tunable 1×4 optical beamforming network (OBFN), based on the hybrid integration of indium phosphide (InP) components in the silicon nitride (Si3N4) platform. The photonic integrated circuit (PIC) comprises a hybrid InP-Si3N4 external cavity laser, a pair of InP phase modulators, a Si3N4 optical single...

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, sensi...

We study the way that chromatic dispersion affects the visibility and the synchronization on quantum key distribution (QKD) protocols in a widely used setup based on the use of two fiber-based Mach–Zehnder interferometers at transmitter/receiver stations. We identify the necessary conditions for the path length difference between the two arms of th...

We present a novel technique for dispersion compensation by exploiting the filtering properties of a fully reconfigurable serially coupled microring resonator (MRR) structure in analog intermediate frequency-over-fiber/mmWave (IFoF/mmWave) fiber/wireless 5G and beyond 5G(B5G)-oriented mobile fronthaul. To this extend, we demonstrate simulation and...

We propose and experimentally demonstrate a photonic integrated circuit (PIC) that operates as an optical equalizer (OE) with multi-rate and multi-channel capability. The OE has the structure of a 3-tap direct form finite impulse response (FIR) filter and is based on the use of micro-ring resonators (MRRs) for the tuning of its delay lines. The PIC...

There is considerable interest in predicting the efficiency of Quantum Key Distribution (QKD) protocols when one of their implementation quantities is modified. One significant imperfection that affects the efficiency of the setup is the afterpulse phenomenon which consists in the spontaneous detections triggered by trapped carriers after previous...

A research contribution focusing on the Quantum Key Distribution (QKD)-enabled solutions assisting in the security framework of an optical 5G fronthaul segment is presented. We thoroughly investigate the integration of a BB84-QKD link, operating at telecom band, delivering quantum keys for the Advanced Encryption Standard (AES)-256 encryption engin...

The transformation of datacentres to support the increasing traffic growth requires the development of new technologies to migrate to 1.6T optical transceivers and to ultra-fast high radix optical space switches. In this work, an outline of the technological perspectives of TWILIGHT project is provided in accordance with research updates and indust...

The NEPHELE hybrid electro-optical datacenter network (DCN) architecture is proposed as a dynamic network solution to provide high capacity, scalability, and cost efficiency in comparison to the existing DCN infrastructures. The details of the NEPHELE DCN architecture and its various key parts are introduced, and the performance of its implementati...

We present a fixed mobile convergence topology for analog intermediate frequency over fiber (A-IFoF)/millimeter-wave (mmWave) transmission, benefiting from the reuse of the deployed passive optical network (PON) infrastructure, towards future mobile fronthaul architectures. Powerful fully programmable gate array boards located inside the access nod...

We study the way that chromatic dispersion affects the error detection probability and the synchronization on Quantum Key Distribution (QKD) protocols in a widely-used setup based on the use of two fiber-based Mach-Zehnder (MZ) interferometers at transmitter/receiver stations. We identify the necessary conditions for the path length difference betw...

We experimentally demonstrate two Analog Mobile Fronthaul concepts exploiting coherent optical systems technology. Single Sideband generation and coherent detection of a 12 Gb/s signal with 6 subcarriers using an IQ modulator is presented along with an extended reach Fiber-Wireless transmission concept using IQM-DD system and V-band radio.

5G advances the wireless communications by providing a significant improvement to the data rate, capability of connected devices and data volumes compared to the previous generations. While these advantages combine along with a wider range of applications to merit the end-user, the technologies to be used are not specified. Considering this problem...

Existing transceiver technology inside data centers will soon reach its limits due to the enormous traffic growth rates driven by new, bandwidth-hungry applications. Efforts to develop the next generation of 800Gbps and 1.6Tbps transceivers for intra-DC optical interconnects have already kicked-off to address the demands in traffic, the exhaustion...

Addressing spectrum related parameters of filtering nodes can assist in enhanced monitoring of WDM-enabled networking. We introduce methods to assess the impact of LCoS-based WSS node impairments based on the QBER/SKR metrics from QKD stations.

The Institute of Accelerating Systems and Applications (IASA) is pursuing research and facilitates postgraduate studies in traditional and cross-disciplinary areas where accelerators play an important role. The first major facility of IASA, now under construction, is a 246 MeV two-stage CW Cascade microtron. The planned experimental programs and fa...

A Wavelength Division Multiplexing (WDM)-enabled analog mobile fronthaul architecture is presented supporting enhanced flexibility by exploiting the fine filtering properties of a fully reconfigurable, silicon photonics-based filtering element. Numerical studies are presented emphasizing on the flexibility, low-energy consumption, and the compatibi...

We present an extensive study on the quantum link multiplexed with intense classical signal in a WSS-based node. Theoretical results on QBER and SKR performance revealed the dependence of BB84-QKD link on passband spectral response.

A Wavelength Division Multiplexing (WDM)- enabled analog mobile fronthaul architecture is presented supporting enhanced flexibility by exploiting the fine filtering properties of a fully reconfigurable, silicon photonics-based filtering element. The use of Photonic Integrated Circuit (PIC)- based elastic optical circuitries to support wavelength se...

Optical networks have historically been designed to be operated statically. Connections are overprovisioned so that they remain uninterrupted over several (e.g., 10) years, using high physical-layer margins to cover the evolution of the physical conditions and modeling uncertainties. As a first step, we can increase the efficiency without sacrifici...

The soaring demand for higher speeds in datacenters to address the relentless growth of the global IP traffic places optical interconnects in the spotlight. In this manuscript, we present a high-speed optical transceiver for intra-datacenter connectivity. The transceiver is based on single-mode, single-polarization high-speed vertical-cavity surfac...

We present simulation and characterization results for the design of a two-port grating coupler with achievable coupling efficiency up to 54% together with simulation and characterization results of three different multimode interference (MMI) coupler structures, 1x2, 1x4 and 1x8 with insertion loss and output power imbalance as low as 0.2 dB and 0...