Nicola Calabretta

Eindhoven University of Technology | TUE · Research Program Electro-Optical Communications (ECO)

Metro-access networks exploiting wavelength division multiplexing (WDM) to cope with the ever-growing bandwidth demands are sensitive to cost and need to be fast-configurable to meet the requirements of many new network services. Optical add-drop multiplexers (OADMs) are a key component in enabling fast dynamic wavelength allocation and optimizatio...

Managing insertion losses, polarizations and device footprint is crucial in developing large-scale photonic integrated circuits (PICs). This paper presents a solution to these critical challenges by designing a semiconductor optical amplifier (SOA) in the O-band with reduced polarization sensitivity, leveraging the ultra-compact InP Membrane on Sil...

We assess the performance of an O-band integrated optical 4x4 switch using the broadcast and select architecture with 100 Gbit/s PAM-4 signals. We measured a power penalty of <1 dB at the FEC-limit for multiple optical paths.

Enabled by digital subcarrier multiplexing and filter-less architectures based on semiconductor optical amplifiers, our point-to-multipoint scheme can cover distances of up to 350 km with OSNR margins > 9.3 dB in typical BT horseshoe networks.

We demonstrate a flexible metro-access network exploiting SOA-based OADM nodes and digital subcarrier multiplexing with power loading. Results show that at least 4 nodes can be supported for 40-Gb/s transmission with bandwidth allocation on demand.

We present the network architecture of Alibaba Cloud DCs and investigate their traffic characteristics based on statistical data and captured traces. The statistical coarse-grained data are in the granularity of one minute, while the captured traces are fine-grained data that are in the granularity of one packet. We study the traffic features from...

Optical wireless data center networks (OW-DCNs), which employ optical wireless technology and optical wired switching technology, are gaining interest as they promise to eliminate cable complexity, as well as to create high bandwidth interconnections and a low-cost and power-efficient system. In particular, the incorporation of optical tunable tran...

Disaggregation in optical networks is particularly relevant to be considered for the deployment of 5G services and towards the support of 6G. Particularly in the metro area network (MAN), this is especially crucial, as is the adoption of suitable photonic technologies enabling dense integration to design a sustainable network architecture. Furtherm...

We experimentally demonstrate a 1x4 WDM polarization-insensitive wavelength selective switch based on bulk SOAs co-integrated with AWGs. Results show a net gain, broadband, and error-free operation with 0.6 dB power penalty up to 25Gbps NRZ-OOK.

We fabricated and assessed a wideband (C-/L- band) nanosecond 1×2 electro-optic switch in 3-µm thick silicon. Results show 2.5dB lowest insertion loss, 16dB averaged extinction ration, 2.5dB polarization dependent loss and 6-ns switching time.

We propose a micro buffer fast optical switch (MFOS) fabric for a data center network. MFOS highly improves the network performance, and achieves 6.7 µs latency and 99.9% throughput at a load of 0.8.

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.

Exploiting a supervisory channel we demonstrate fast FPGA-based control and switching for transparently photonically connected edge data centers. Results show microsecond-time control, time-slotted operation and deterministic latency with nanosecond jitter supporting time sensitive applications.

Semiconductor optical amplifiers (SOAs) are building blocks of several active photonic integrated circuits such as lasers and all optical switches. However, the optimization of SOAs is a computationally expensive task due to the high dimensionality of the problem (i.e SOA length, Recombination Parameters, gain coefficient, among others) and the rel...

We have designed, fabricated, and characterized a low polarization dependent multicast and select (MCS) switch based on a newly developed novel bulk SOA co-integrated with passive waveguides. The proposed new bulk SOA-based MCS switch requires the co-integration of active SOAs (gate and booster) with several passive InP elements. First, we have pre...

A 40-channels 100 GHz spaced (de-)multiplexer (Demux/Mux) based on cascaded planar Echelle gratings (PEGs) with low crosstalk and insertion loss is designed and fabricated on 3-μm Silicon-on-Insulator (SOI) platform. The low crosstalk level 40-channels Demux/Mux is effectively achieved by cascading one 1×8 100 GHz spacing cyclic PEG with 800 GHz fr...

As the global internet protocol (IP) traffic volume growth puts more pressure on network connectivity, bandwidth and latency requirements, crucial network elements such as switches need continuous improvement. To this end, we report a monolithically integrated, ultra-compact 8×8 optical space switch based on semiconductor optical amplifier (SOA) ga...

Low polarization-dependent semiconductor optical amplifiers (SOAs) with an easy fabrication process and the capability to be co-integrated with passive elements are crucial in photonic integrated circuits. In this work, we design, simulate, and optimize a low polarization-dependent bulk SOA based on a novel layerstack with an unstrained bulk active...

We experimentally demonstrate the emulation of scaling of the semiconductor optical amplifier (SOA) based integrated all-optical neural network in terms of number of input channels and layer cascade, with chromatic input at the neuron and monochromatic output conversion, obtained by exploiting cross-gain-modulation effect. We propose a noise model...

Optical wireless data center networks (OW-DCNs), featuring no cable complexity, low latency, and high throughput, are highly attractive for the next generation of DCNs, while photonic integration provides a compact, low-power, and low-cost solution. In this Letter, we propose a novel, to the best of our knowledge, OW-DCN architecture using photonic...

Internet-generated traffic growth is forcing the development of new low-cost solutions in metropolitan area networks (MANs), in particular in the transceiver and network node architectures. Semiconductor optical amplifier (SOA)-based wavelength blockers can be used as fundamental building blocks to add and drop optical channels in the node architec...

Optical switches are fundamental building blocks for high‐speed optical networks and basic blocks towards all‐optical networks for future communications that utilize wavelength division multiplexing (WDM) with high‐speed multiple modulation formats to boost the single‐channel data rate to hundreds of Gbps. Photonic switching based on semiconductor...

The ever-expanding growth of internet traffic enforces deployment of massive Data Center Networks (DCNs) supporting high performance communications. Optical switching is being studied as a promising approach to fulfill the surging requirements of large scale data centers. The tree-based optical topology limits the scalability of the interconnected...

To overcome the bandwidth bottleneck of electrical switches in data center networks (DCNs), switching the traffic in the optical domain has been much investigated as a future‐proof solution supplying ultra‐bandwidth. To date, many optical switch solutions have been investigated, exploiting various building blocks, such as 3D MEMS, LCoS display matr...

An ultrawide-band (UWB), O- to L- band, polarization insensitive (PI) 1 × 12 100 GHz channel spacing arrayed waveguide grating (AWG) is designed and realized in 3-μm Silicon-on-Insulator (SOI) platform. PI and UWB operations are achieved by directly exploiting the UWB 3-μm PI silicon waveguide as the arrayed waveguide. The PI AWG can be employed as...

Switching the traffic in the optical domain has been considerably investigated as a future-proof solution to overcome the intrinsic bandwidth bottleneck of electrical switches in data center networks (DCNs). However, due to the lack of fast and scalable optical switch control mechanism, the lack of optical buffers for contention resolution, and the...

Electrical switching based data center networks have an intrinsic bandwidth bottleneck and, require inefficient and power-consuming multi-tier switching layers to cope with the rapid growing traffic in data centers. With the benefits of ultra-large bandwidth, high-efficient cost and power consumption, switching traffic in the optical domain has bee...

In order to meet the massively increasing requirements of big-data applications, data centers (DCs) are key infrastructures to cope with the associated demands, such as high performance, easy scalability, low cabling complexity and low power consumption. Many research efforts have been dedicated to traditional wired data center networks (DCNs). How...

Optical switching, which benefits from high bandwidth and low latency, promises to revolutionize data center networks that suffer from a bandwidth bottleneck and hierarchical structure. However, the lack of adaptable and fast optical switch control schemes, the lack of optical buffers for contention resolution, and the high cost of clock and data r...

We demonstrate the use of a wavelength converter (WC), based on cross-gain modulation in a semiconductor optical amplifier (SOA), as nonlinear function co-integrated within an all-optical neuron realized with SOA and WDM technology. We investigate the impact of fully monolithically integrated linear and nonlinear functions on the all-optical neuron...

We experimentally demonstrate a disaggregated metro area network that includes new photonic devices, node architectures, and sliceable bandwidth/bitrate variable transceiver, transmitting up to 8 × 11=88 spatial/spectral channels for a total capacity of 1.676Tb/s.

Convolutional neural network (CNN) is one of the best neural network structures for solving classification problems. The convolutional processing of the network dominates processing time and computing power. Parallel computing for convolutional processing is essential to accelerate the computing speed of the neural network. In this paper, we introd...

We present efficient titanium dioxide-TiO 2 directional coupler integrated with single mode waveguide as an effective solution for switching and splitting at 1550nm wavelength. The 100/0 and 50/50 directional coupler show efficiency of 96.65% and 98.58%, respectively, which is so far reported the highest with TiO 2 based directional coupler.

Future optical metro access networks will connect heterogeneous access technologies like beyond 5G radio access networks and edge computing interconnections. These access networks and their diversified use cases will impose significant challenges on network capacity, wavelength resource and network synchronization. In this paper, we present and inv...

Low polarization-dependent semiconductor optical amplifiers (SOA) co-integrated with passive circuits via an easy fabrication process are highly demanded in optical communication systems. However, despite several SOAs have been reported, co-integration of polarization-independent bulk SOA with passive waveguides in the InP platform to generate comp...

We present an ultra-wide band photonic integrated ${{4}} \times {{4}}$ 4 × 4 polymer cross-bar switch matrix based on total internal reflection and the thermo-optic effect. The photonic integrated polymer switch owns low insertion loss, low power consumption, wavelength, and polarization-independent operation for all switching paths. The experiment...

The rapid increasing traffic in data centers (DCs) puts tremendous pressure to the present multi-tier network architectures and electrical switching techniques. Switching traffic in the optical domain featuring ultra-high bandwidth, therefore, has been intensively investigated to build the high capacity data center networks (DCNs). To handle the va...

Optical networks based on fast optical switches (FOSes) could potentially solve the latency, bandwidth, cost and power consumption challenges in current electrical switches (ESes) based high performance computing (HPC) networks. In this work, we present a novel HPC network which employs distributed FOS interconnecting by removing ES (Firefly). In F...

As fiber-optic systems turn toward multi-band transmission (MBT), exploiting the complete low loss window of optical fibers, novel optical components, able to operate in bands other than the conventional C-band, become necessary. In light of this, we report on a multi-band photonic integrated 1 x 2 wavelength selective switch (WSS) operating in the...

We investigate the scalability and performance of a novel optical wireless data center network (OW-DCN) based on passive diffractive optics and fast tunable transmitters. The proposed OW-DCN architecture consists of two parallel inter- and intra- cluster networks to implement a flat communication between the top of racks within the DCN with at most...

We demonstrate an optical wireless DCN architecture employing fast switches and reconfiguration with FPGA-based ToRs and SOA-based wavelength switch. Experimental investigation indicates 13.3ns switching time and 1E-5 packet loss by SDN-assisted reconfiguration with automatic reallocation.

The computing industry is rapidly moving from a programming to a learning area, with the reign of the von Neumann architecture starting to fade, after many years of dominance. The new computing paradigms of non-von Neumann architectures have started leading to the development of emerging artificial neural network (ANN)-based analog electronic artif...

The explosive traffic growth of emerging cloud, augmented/virtual reality, artificial intelligence, and 5G applications along with the inherent need for high-bandwidth transport of big data has fueled the expansion of the Ethernet switch market for data centers (DCs), high-performance computers (HPCs), and 5G fronthaul networks. As such, next-gener...

Maintaining high-performance operation under dynamic and nonuniform network traffic has been a technical challenge in current data center networks (DCNs). With the aim to provide better quality of service (QoS) for diverse applications, this work presents a dynamic and adaptive DCN reconfiguration framework based on deep reinforcement learning (DCR...

In elastic optical inter-datacenter networks, multiple software-defined networking (SDN) controllers have been used to improve scalability and reliability. The static controller deployment faces the problem of controller load imbalance under dynamic changes in network traffic. In response to this problem, existing research works proposed to use dyn...

The upcoming 5G and beyond 5G heterogeneous applications with different quality of service (QoS) will impose strict latency, bandwidth, and flexibility requirements on the optical metro access network. The conventional cloud computing is gradually unable to fulfill the application requirements, especially on latency due to the distance causing prop...

We propose a novel optical wireless data center network based on passive diffractive optics and fast tunable transmitters. Transmission performance of the proposed network with 8×8 racks is assessed with 20-Gb/s NRZ-OOK. Results show a maximum power penalty of 1dB.

We design and numerically analyze low polarization sensitive bulk-SOA in the O-band suitable for co-integration with passive waveguides/circuits. Low polarization dependent gain (<1.5dB) is achieved with 20dB average gain and 11dBm output saturation power.

For the first time we have designed and demonstrated polarization insensitive, high gain and broadband 1×8 broadcast and select switch suitable for optical packet switching system based on bulk SOAs integrated with passive elements.

We demonstrate the first optical processing of up to 9-bit/symbol multi-level modulated channels on a complete all-optical SOA-based neuron, with an error of 0.08. A higher number of modulation levels and inputs can improve accuracy.

C- and L-band polarization insensitive 1×12 AWG with 100GHz channel-spacing is fabricated on SOI. Results show <3.8dB loss, <-30dB crosstalk, <2.6dB polarization dependent loss, <0.1nm polarization dependent wavelength shift and <0.3dB BER penalty at 10Gbps.

We experimentally evaluate an InP 1×8 photonic integrated wavelength selective switch based on SOA optical gates. Results show error-free operation with a limited penalty at 10 and 40 Gb/s NRZ-OOK, on-chip gain >7 dB and cross-talk <−45 dB.

A fast switch and control system is developed for the practical deployment of optical switches in DCNs. Implemented label control and OFC technique experimentally achieve zero packet-loss and 5µs server-to-server latency at 0.5 traffic load.

We demonstrate 4×35 Gbps error-free WDM data routing in a lossless compact 8×8 InP optical space switch with 2 dB worst-case penalty. 10 dB IPDR within 1.5 dB power penalty is measured at 12.5 Gbps.

A disaggregated DCN prototype based on nanoseconds optical switch is experimentally assessed. Results show a network latency of 122.3ns, no packet loss, and error-free operation with power penalty of 0.5dB at BER of 1E-9.

We have experimentally demonstrated a 1x8 WDM polarization-insensitive multicast switch based on bulk SOAs. Results show net gain of 11dB, broadband and error-free operation with 0.55dB power penalty at 10GBps NRZ-OOK, and crosstalk <-39dB.

We propose a traffic r ate m atrix d ecomposition ( TRMD) b ased c onflict free scheduling for a fast optical switching network and show that TRMD outperforms a flow con- trol protocol with < 10µs latency and > 92% throughput at load of 1.

Nanoseconds WDM optical switch is exploited to implement a rack-scale memory disaggregated datacenter network (DCN). Numerical and experimental results validate the disaggregated DCN architecture prototype with 122.3ns network latency, zero packet loss, and error-free operation.

An ultra-wide band (O to L) 4×4 polymer switch matrix is experimentally demonstrated. Results show <0.6dB polarization-dependent loss, >36dB switching ratio, <6.5dB fiber-to-fiber loss, and error-free operation with <0.15dB power penalty at 10Gb/s and 50Gb/s.

The effect of SOA-based MAN node crossing on DMT high-capacity transmission is experimentally evaluated. A capacity of more than 50 Gb/s per channel is demonstrated for a multi-hop multi-channel transmission up to 116 km SSMF.

We report a multicast switch PIC serving as a transponder aggregator. Successful data transmission through InP multicast switch and reception in a fully packaged coherent receiver demonstrates the drop traffic flow of a ROADM node.

We experimentally verify the noise modeling of SOA-based all-optical neural networks on the OSNR degradation of the neuron: The photonic neural network can scale up to 16×16 neurons per layer, resulting in NRMSE <0.10.

We present an efficient titanium dioxide-TiO 2 grating coupler integrated with single mode waveguide, which allows fiber-to-chip coupling efficiency of 50%. This is so far reported the highest coupling efficiency with TiO 2 based grating coupler.

Loss-less nodes based on semiconductor optical amplifiers to enable add/drop functionalities are studied in order to preserve the traffic throughput when adopting high-capacity multicarrier signal formats in metropolitan area networks.