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We demonstrate for the first time a four-node trusted-node-free metro network configuration with dynamic discrete-variable quantum key distribution DV-QKD networking capabilities across four optical network nodes. The network allows the dynamic deployment of any QKD link between two nodes of the network, while a QKD-aware centralised software-defined networking (SDN) controller is utilised to provide dynamicity in switching and rerouting. The feasibility of coexisting a quantum channel with carrier-grade classical optical channels where both the quantum and classical channels are in the C-band over field-deployed metropolitan networks and laboratory-based fibres (

We review and discuss the practicalities of integrating Quantum Key Distribution within the service provider fiber network.

Quantum networks scale the advantages of quantum communication protocols to more than just two distant users. Here we present a fully connected quantum network architecture in which a single entangled photon source distributes quantum states to a multitude of users [1] and our work scaling the network to a complete end to end metropolitan quantum network with 8 users [2] . Our network architecture optimises the resources required by each user without sacrificing security or functionality. We established several long-distance loopback connections and demonstrated extended stable operation with high secure key rates. Unlike previous attempts at multi-user networks, which have been based on active components, and thus limited to some duty cycle, our implementation is fully passive. Further, we present our efforts towards coexistence of 100 Gbps classical communication and all quantum channels used in the network over the same deployed optical fibres.

We describe the status of Quantum Key Distribution and highlight the developments required for this technology and describing a full QKD network. We set out the major differences between QKD and the Quantum Internet.

Quantum Key Distribution (QKD) has emerged as the technology to offer ultimate security, posing additional challenges in the physical layer due to its single-photon nature. Co-existence with classical data and switching aspects are discussed in dynamic-QKD applications for inter- data-centre communications and switched entanglement-based quantum distribution.

On the basis of profound understanding of data center (DC) traffic demands and optical switching technologies, we present a hybrid optical network design for future data center network (DCN). Such design integrates optical circuit switching (OCS) and optical packet switching (OPS) schemes via hybrid Top-of-the-Rack (ToR) switches which provide flexible function-switchover between different traffic patterns in the DCN. Simulations of network behaviors under such DC traffic loads indicate that the proposed OPS/OCS DCN can effectively improve the network performance. Moreover, via a preliminary analysis of OCS and OPS network configurations, the construction of hybrid DCN is also proved as the most cost- and energy-efficient way for DCN upgrading while offering a promised quality of service. An experimental demonstration shows a complete implementation of data center virtualization in the proposed hybrid data center network.

Quantum key distribution (QKD) is a state-of-the-art method of generating cryptographic keys by exchanging single photons. Measurements on the photons are constrained by the laws of quantum mechanics, and it is from this that the keys derive their security. Current public key encryption relies on mathematical problems that cannot be solved efficiently using present-day technologies; however, it is vulnerable to computational advances. In contrast QKD generates truly random keys secured against computational advances and more general attacks when implemented properly. On the other hand, networks are moving towards a process of softwarization with the main objective to reduce cost in both, the deployment and in the network maintenance. This process replaces traditional network functionalities (or even full network instances) typically performed in network devices to be located as software distributed across commodity data centers. Within this context, network function virtualization (NFV) is a new concept in which operations of current proprietary hardware appliances are decoupled and run as software instances. However, the security of NFV still needs to be addressed prior to deployment in the real world. In particular, virtual network function (VNF) distribution across data centers is a risk for network operators, as an eavesdropper could compromise not just virtualized services, but the whole infrastructure.We demonstrate, for the first time, a secure architectural solution for VNF distribution, combining NFV orchestration and QKD technology by scheduling an optical network using SDN. A time-shared approach is designed and presented as a cost-effective solution for practical deployment, showing the performance of different quantum links in a distributed environment.

Network infrastructure must support emerging applications, fulfill 5G requirements, and respond to the sudden increase of societal need for remote communications. Remarkably, crowdsourced live video streaming (CLVS) challenges operators’ infrastructure with tides of users attending major sport or public events that demand high bandwidth and low latency jointly with computing capabilities at the networks’ edge. The Metro-Haul project entered the scene proposing a cost-effective, agile, and disaggregated infrastructure for the metro segment encompassing optical and packet resources jointly with computing capabilities. Recently, a major Metro-Haul outcome took the form of a field trial of network function virtualization (NFV) orchestration over the multi-layer packet and disaggregated optical network testbed that demonstrated a CLVS use case. We showcased the average service creation time below 5 min, which met the key performance indicator as defined by the 5G infrastructure public private partnership. In this paper, we expand our field trial demonstration with a detailed view of the Metro-Haul testbed for the CLVS use case, the employed components, and their performance. The throughput of the service is increased from approximately 9.6 Gbps up to 35 Gbps per virtual local area network with high-performance VNFs based on single-root input/output virtualization technology.

Quantum Key Distribution (QKD) has been identified as a secure method for providing symmetric keys between two parties based on the fundamental laws of quantum physics, making impossible for a third party to copy the quantum states exchanged without being detected by the sender (Alice) and receiver (BoB) and without altering the original states. However, when QKD is applied in a deployed optical network, physical layer intrusions may occur in the optical links by injecting harmful signals directly into the optical fibre. This can have a detrimental effect on the key distribution and eventually lead to its disruption. On the other hand, network architectures with software defined networking (SDN) benefit from a homogeneous and unified control plane that can seamlessly control a QKD enabled optical network end-to-end. There is no need for a separate QKD control, a separate control for each segment of an optical network and an orchestrator to coordinate between these parts. Furthermore, SDN allows customised and application tailored control and algorithm provisioning, such as QKD aware optical path computation, to be deployed in the network, independent of the underlying infrastructure. Therefore, in this manuscript, we investigate the integration of the application, SDN and QKD infrastructure layers and confirm capability for flexible supervision and uninterrupted key service provisioning in the event of link level attacks. An experimental demonstrator is used, for the first time, to verify the architecture proposed, considering real-time monitoring of quantum parameters and fiber-optic link intruders to emulate real-world conditions. Furthermore, attacks on a standard single-mode fiber (via a 3dB coupler) and a multicore fiber (via an adjacent core) are undertaken to explore different connectivity between QKD units. Results show an additional attacker identification and switching time of less than 60ms for the link cases investigated, being negligible compared to the total (re)-initialization time of 14 minutes of the QKD units.

We successfully demonstrate coexistence of record-high 11.2 Tb/s (56x200Gb/s) classical channels with a discrete-variable-QKD channel over a multicore fibre. Continuous secret key generation is confirmed together with classical channel performance below the SDFEC limit and a minimum quantum channel spacing of 17nm in the C-band.

First demonstration of quantum-secured end-to-end VNS composition through dynamic chaining of VNFs from multiple-domains. We rely on a novel quantum-switched flexi-grid WDM network and q-ROADM for inter-connectivity and on-demand selection of transport functions for quality-of-service.

A software-defined IoT network is integrated with fibre-based QKD technology to provide the IoT devices with quantum-secure keys to enhance their battery lifetime. Experimental demonstration reveals an 18% energy efficiency improvement compared to the standard device key generation.

A coordinated optical power optimisation strategy over per-fibre-span and ROADMs is proposed to increase the network throughput. The simulation shows the strategy can improve network throughput by 15%. The experiment demonstration verifies 0.7 dB SNR improvement per lightpath.

This paper reports all-optical, function programmable, transparent, intra- and inter-data center networking (DCN) using space and time-division multiplexing (SDM/TDM) within data centers and wavelength division multiplexing (WDM) between data centers. A multielement fiber is used for SDM transmission to provide a large quantity of optical links between the top-of-racks (ToRs) and the function programmable cluster switch. Beam-steering large-port-count fiber switches, used as central cluster switches and intercluster switch, provide a single hop optical circuit switching solution, and also enable network function programmability for DCN to support variable traffic patterns and different network functions. A TDM switch as a plug-in function provides intra-cluster communication with variable capacity and low latency. The flat-structured intra data center architecture, with a circuit-switched SDM and TDM hybrid network enables scalable, large-capacity and low-latency DCN communication. In addition, all-optical ToR-to-ToR inter-DCN is realized through metro/core networks. A highly-nonlinear fiber based all-optical SDM-to-WDM converter transfers three SDM signals to three-carrier spectral superchannel signals, which are transmitted to the destination DCN, through the metro/core networks. The all-optical ToR-ToR cross-DCN connections enable the geographically distributed DCNs to appear as one big data center.

Optical Ethernet gains great success in varied optical domains. Ethernet while providing the elastic allocation of bandwidth per flow is currently restricted to being transported over fixed-rate fixed-grid optical channels. However, as data transmission and switching in optical networks is becoming more flexible, the current Ethernet to optical interface with fixed functions and fixed design face great challenges for applications in an elastic optical network. In addition, the coexisted Ethernet standards in optical networks also need a converter to transform low-capacity Ethernet signals to high-capacity Ethernet signals. In this paper, we propose a real-time Ethernet to software-defined programmable sliceable transponder based on network function programmable Ethernet to elastic optical networks (ETH-EON) interface, multiformat supported transmitter and architecture-on-demand (AoD)-based superchannel signal processor. The transponder parses the Ethernet traffic and then transports it over a number of optical carriers with the appropriate baud-rate, modulation format and associated spectral bandwidth. Software-defined reconfigurability of both electronic (i.e., FPGA) and optics (AoD) allow for a flexible transponder to offer high Ethernet to optical transport efficiency. Ethernet capacities from 40 Gbit/s to 2.88 Tbit/s can be provided by reconfiguring the modulation formats and the used optical carrier number. The modulation format adaptability also provides a tradeoff between transmission capacity and transmission distance, to optimize network performance. The designed software-defined sliceable elastic transponder aggregate multiple Ethernet traffic flows and send spectral-efficient signals through the elastic optical network with simple Ethernet protocols, avoiding using complex and expensive OTN technologies. Finally, we demonstrate the converter in elastic optical networks for several application scenarios.

A scheme for the conversion of spatially multiplexed channels to a wavelength superchannel is presented and characterized. The viability of deployment of this scheme at network nodes located at the boundaries between spatial-division-multiplexed and standard single-mode fiber wavelength division multiplexed networks is demonstrated.

This article reports the work on next generation transponders for optical networks carried out within the last few years. A general architecture supporting super-channels (i.e., optical connections composed of several adjacent subcarriers) and sliceability (i.e., subcarriers grouped in a number of independent super-channels with different destinations) is presented. Several transponder implementations supporting different transmission techniques are considered, highlighting advantages, economics, and complexity. Discussions include electronics, optical components, integration, and programmability. Application use cases are reported.

We experimentally demonstrate, for the first time, DDoS mitigation of QKD-based networks utilizing a software defined network application. Successful quantum-secured link allocation is achieved after a DDoS attack based on real-time monitoring of quantum parameters, Comment: Accepted for presentation in OFC 2018 Conference. M2A.6

Record-high 13.625 Gb/s real-time end-to-end dual-band optical orthogonal frequency division multiplexing (OFDM) transmissions are experimentally demonstrated over intensity modulation and direct detection-based 25 km standard single-mode fibres utilising 1.125 GHz reflective semiconductor optical amplifier (RSOA) intensity modulators. The 7.375 Gb/s OFDM baseband (0–2 GHz) and 6.25 Gb/s OFDM passband (4.125–8.125 GHz) are adaptively modulated independently and sampled at 4 GS/s. Experimental results show that strongly saturated RSOAs can intensity-modulate adaptive bit- and power-loaded radio frequency (RF) OFDM signals having bandwidths approximately eight times higher than the 3 dB small-signal modulation bandwidths of the RSOAs.

In aggregated 11.25 Gb/s over 25 km SSMF intensity-modulation and direct-detection (IMDD) optical OFDM multiple access passive optical networks (OOFDMA PONs) incorporating colorless ONUs based on reflective semiconductor optical amplifier (RSOA) intensity modulators, excellent agreements are obtained between real-time upstream experimental measurements and numerical simulations for various system operating conditions. Making use of experimentally verified theoretical models and component/system parameters, extensive numerical explorations are undertaken, for the first time, of the impact of the number of ONUs on both upstream optical power budget and minimum ONU wavelength spacing required for eliminating the optical beat interference effect. It is shown that the minimum ONU wavelength spacing is independent of the number of ONUs, and that doubling the number of ONUs simultaneously accommodated in the aforementioned PON architectures gives a 1.9 dB reduction in upstream power budget. Results also show that the utilization of an optimum frequency-offset super-Gaussian optical filter at an order of 5 immediately after the RSOA intensity modulator in each ONU can significantly improve the upstream power budget by >5.3 dB, and simultaneously enhance the upstream power budget robustness to variations in the number of ONUs.

Edge Data Centres (EDC) are often managed by a single administrative entity with logically centralized control. The architectural split of control and data planes and the new control plane abstractions have been touted as Software-Defined Networking (SDN), where the OpenFlow protocol is one common choice for the standardized programmatic interface to data plane devices. However, in the design of an SDN architecture, there is no clear distinction between functional network parts such as core and edge elements. It means that all switches require to support lookups over hundreds of bits with complex actions that have to be specified by multiple tables. In this paper, we propose a new programmable architecture for EDC networks, named Residues Defined Networks (RDN). In RDN, a controller defines a network policy (e.g. connectivity protection) setting flow entries at the edges. Based on these entries, the edge switches assign route-IDs to flows. A route is defined as the remainder of the division (Residue) between a route-ID and a set of switch-IDs within RDN core. In case of failures, emergency routes are compactly encoded as programmable residues forwarding paths written into the packets. RDN scalability is evaluated considering 2-tier Clos topologies which cover mostly EDC deployments supporting up to 2304 servers. A RDN proof-of-concept prototype is implemented in Mininet for network emulation. Also, to increase the accuracy on latency measures, we implement RDN in NetFPGA that is validated in a testbed with 10Gbps Ethernet boards. RDN offers ultra-fast failure recovery (sub-milliseconds carrier grade), achieves low latency with RDN switching time per hop ( 0.6 microseconds) and no jitter within the RDN core.

We show experimentally, for the first time, that an increasing subcarrier order in m-CAP optical-links does not result in proportional data-rate gain. We show that 10-CAP offers similar performance to 20-CAP with substantially less complexity.

For future multi-dimensional optical networks, vast network resources provided by space division multiplexing and wavelength division multiplexing technologies, require new network architectures to scale up current network functions. The huge switch-granularity range requires a more dynamic way to deploy network resources. In this paper, we proposed a hardware-programmable optical network which deploys network resources according to incoming trac requests. The proposed network supports node function programmability and node architecture adaptability, which are critical for dynamic function and resources deployments. Architecture-on-Demand based node architecture adapts node architectures and also enables network function programmability by incorporating with several exible node functions. Other enabling technologies, such as ubiquitous power monitoring and dynamic optical power management, assures the programmable optical node work properly. Based on all these technologies, we established a hardware-programmable optical network testbed. Several use cases were demonstrated successfully, such as dynamic power equalization and optical debugging. Theseworks veried the feasibility of hardware-programmable optical network, which dynamically allocate network resources for service provision. The proposed hardware programmable optical network will lead to a betterhardware utilization and provide a possible solution for the future multi-dimensional optical network.

In directly modulated vertical cavity surface-emitting laser (DM-VCSEL)-based, end-to-end real-time, 11.25-Gb/s optical orthogonal frequency division multiplexing (OOFDM) systems utilizing legacy OM1/OM2 multimode fibers (MMFs), as well as simple intensity-modulation and direct-detection (IMDD) detailed experimental explorations, are undertaken, for the first time, for the effectiveness of various optical launching conditions, including center launching and conventional offset launching in maximizing the transmission distances of the legacy MMF systems. It is shown that, in the aforementioned legacy MMF systems, center launching enables an adaptive power-loaded OOFDM transmission at a raw signal bit rate of 11.25 Gb/s over an unprecedented distance of 2000 m with an optical power penalty as low as 0.8 dB. When center launching is replaced by conventional offset launching, the transmission distance of the legacy MMF system is reduced to 300 m, and the corresponding optical power penalty is increased to 2.3 dB. Comparisons of measured maximum achievable transmission distances of various MMF IMDD system configurations subject to different launching conditions show that DM-VCSEL-based, adaptive power-loaded OOFDM at center launching is a viable and cost-effective solution for use in legacy MMF systems. This work may have great potential for upgrading installed MMF local area networks to 10 Gb/s and beyond.

Detailed investigations of dynamic negative power penalty characteristics of optical orthogonal frequency division multiplexing (OOFDM) signal transmissions are undertaken, for the first time, in directly modulated distributed feedback (DFB) laser (DML)-based intensity modulation and direct detection (IMDD) systems incorporating negative dispersion fibers such as MetroCor fibers. Excellent agreements between numerical simulations and real-time experimental measurements are obtained over a wide diversity of transmission conditions of the aforementioned systems. The physical mechanism underpinning the occurrence of negative power penalties is the reduction in subcarrier intermixing impairment due to the compensation between DML positive frequency chirps and MetroCor negative chromatic dispersions. It is also shown that the negative power penalty is independent of both cyclic prefix and signal modulation format and, more importantly, controllable when adaptive modulation and/or appropriate adjustments of DML operating conditions are applied.

We show the first hitless 100Gbit/s real-time bandwidth-variable transmitter integrated with restful server and OTN switching matrix. Between 10.7Gbit/s and 107Gbit/s, the transmitter reconfigures in less than 450μs without packet loss and additional penalty.

Theoperation of multidomain and multivendorEONs can be achieved by interoperable sliceable bandwidth variable transponders (S-BVTs), a GMPLS/BGP-LS-based control plane, and a planning tool. The control plane is extended to include the control of S-BVTs and elastic cross connects, which combine a large port-count fiber-switch (optical backplane) and bandwidthvariable wavelength-selective switches, enabling the end-to-end provisioning and recovery of network services. A multipartner testbed is built to demonstrate and validate the proposed end-toend architecture. Interoperability among S-BVTs is experimentally tested between different implementations. In this case, transponders are configured using the proposed control plane. The achieved performance with hard-decision and soft-decision FECs using only the information distributed by the control plane is measured against the performance of the single-vendor implementation, where proprietary information is used, demonstrating error-free transmission up to 300 km. © 2016 IEEE.

A common Transport API is proposed for joint cloud/network orchestration, allowing interworking of heterogeneous control planes to provide provisioning/recovery of QoS-aware E2E services. We present its first demonstration in a multi-partner testbed including data-plane monitoring.

An adaptive optical data center network architecture is, for the first time, proposed and simulated. Data center traffic loads are efficiently accommodated by FTP solution, supported by synthetic optical packet/circuit switching scheme and dynamic function-topology management.

The flexibility and trade-offs of node subsystems are evaluated for the first time under different design configurations. The proposed method presents a direct approach to identify the impact of various key subsystems figures of merit for add/drop networks and EONs.

Due to the large transmission speeds and enormous volumes of transferred data, network availability performance is one of the key issues in optical long-haul networks, comprising nodes implemented by optical cross-connects (OXCs). In this context, the design of OXCs is becoming very challenging since they have to support both legacy lower bit-rates and future highspeed super-channels by means of flexible allocation of spectral resources, and at the same time provide high availability of established connections. In this paper we study the availability and power consumption of different node architectures. We focus on the design of the new generation of synthetic programmable OXCs based on the Architecture on Demand concept which can reduce the number of utilized node components when a certain part of signals is switched at the fibre level, resulting in lower mean down time and power consumption compared to traditional node architectures.

A multi-domain optical infrastructure with end-to-end Ethernet transport capability can deliver Ethernet services over a large scale and provide a promising solution for inter data center networks (DCN) communication. The already existed metro and core networks should be evolved both in data plane and control plane towards to support the heterogeneous and dynamic Ethernet traffic environment. In this paper, we report the work carried out in the ICT STRAUSS project to provide Ethernet connections for intra-DCN and inter-DCN over metro and core networks. The key technologies for intra- and inter- DCN communications are reported with experimental validation.

Record-high 25.25-Gb/s real-time end-to-end optical orthogonal frequency-division multiplexing transmissions over an intensity-modulation and direct-detection-based 300-m OM2 multi-mode fiber links are achieved with a tri-sub-band transceiver architecture. A 9.75-Gb/s baseband signal is RF multiplexed with two 7.75-Gb/s sub-bands, which are IQ modulated onto a 6.125-Gdirect-detectionHz RF carrier. The adaptive bit/power-loaded, independently power-optimized sub-bands sampled at 4 GS/s are multiplexed to intensity modulate an EML. Similar BERs and optical penalties are observed for all sub-bands.

We demonstrate a real-time Elastic Interface for future flex-grid networks with a software-defined symbol rate transmission. Using PDM-QPSK modulation, live experiments show a line rate adaptation from 10.7 to 107Gbit/s with a sub-millisecond reconfiguration time.

We show an all-optical ultra-low latency server-to-remote memory/storage data center interconnection, exploiting programmable, flexible, bi-directional and data-rate transparent 4×16 Spectrum Selective Switches and supporting elastic WDM/TDM services using fast nanosecond tunable lasers.

Synthesis, placement and configuration of SSS and EDFAs for different power balance scenarios is presented, for the first time, for function programmable optical node architectures. Comparison on device's number and OSNR performance are reported.

We quantitatively measure and evaluate the flexibility of key optical devices of ROADMs considering maximum system entropy. We analyze the dependency and trade-offs between flexibility, connectivity, capacity, granularity and spectral efficiency, key design performance indicators.

This paper describes the general architecture for a sliceable bandwidth variable transponder as identified within the IDEALIST European project. The capability of generate super-channels (optical connections with several adjacent optical sub-carriers) and the slice-ability (super-channels generated together but independently routed in the network towards different destinations) are the key elements of the considered architecture.

The fastest ever 11.25-Gb/s real-time end-to-end optical orthogonal frequency-division-multiplexing (OOFDM) transmission over 500-m multimode fibers (MMFs) with a high electrical spectral efficiency of 5.625 bit/s/Hz is experimentally demonstrated, for the first time, in a simple intensity modulation and direct detection (IMDD) system employing a directly modulated distributed-feedback (DFB) laser. An optical power budget as high as 12 dB is achieved with a minimum received optical power of -6.3 dBm for a total channel bit-error rate of 1 × 10-3. The field programmable gate array (FPGA)-based OOFDM transceivers also have functionalities including variable power loading, performance monitoring, and on-line parameter adjustment.

This study looks into network planning issues for synthetic MCF-based SDM networks implemented through programmable ROADMs. The results show that significant savings in switching modules and energy ...

© 2014 Systematic Paris Region Systems and ICT Cluster. A real-time Ethernet to reconfigurable superchannel data converter is demonstrated in a flexigrid EON network. Ethernet packets are aggregated and groomed by an FPGA-based optoelectronics to a reconfigurable superchannel signal with variable capacity from 160Gbit/s to 2.56Tbit/s.

The paper demonstrates the concept of optical networks with nodes implemented by the architecture on demand (AoD) and proposes a procedure for finding out possible benefits of AoD application, related to node and network availability. AoD node structure enables efficient failure management by creating a set of redundant components, which can be used for self-healing of optical nodes after failure. Availability evaluation procedure is based on Monte Carlo simulation of times to failure/repair of network components. A case study network with AoD nodes is compared to the network with hard-wired nodes in regard to availability performance, and results are presented.

Optical injection locking (OIL) is an effective approach for significantly enhancing the modulation bandwidths of VCSELs. The frequency responses of OIL-VCSELs are, however, very sensitive to the applied OIL conditions. This brings about strong difficulties in practically utilizing the OIL-enhanced modulation bandwidths to achieve highly robust transmission performances of directly modulated OIL-VCSEL-based multi-mode fibre (MMF) links for cost-sensitive application scenarios such as data-centers. In this paper, directly modulated OIL-VCSEL-based real-time dual-band optical OFDM (OOFDM) transceivers with tunability in both the electrical and optical domains are experimentally demonstrated, for the first time, utilizing DACs/ADCs at sampling speeds as low as 4GS/s. The transceivers can support 15.125Gb/s adaptive OOFDM transmissions over 100m OM2 MMF links based on intensity modulation and direct detection. More importantly, the adaptability and tunability of the demonstrated transceivers enable the achievement of excellent robustness of the aggregated OOFDM transmission capacity to OIL condition variations. It is shown that, over a large diversity of OIL conditions that give rise to significantly different system frequency responses, the aggregated OOFDM transmission capacity only vary by

The 7.5-Gb/s real-time end-to-end optical orthogonal frequency-division-multiplexing (OOFDM) transceivers incorporating variable power loading on each individual subcarrier are demonstrated experimentally using a live-optimized reflective semiconductor optical amplifier intensity modulator having a modulation bandwidth as narrow as 1 GHz. Real-time OOFDM signal transmission at 7.5 Gb/s over 25-km standard single-mode fiber is achieved across the C-band in simple intensity modulation and direct detection systems without in-line optical amplification and dispersion compensation.

Utilizing 1GHz RSOAs and 4GS/s DACs/ADCs, record-high 17.125Gb/s real-time dual-band OOFDM transmissions with 7dB receiver sensitivity improvements over IMDD-based 25km SSMFs are experimentally demonstrated, which show excellent robustness to 20dB variations in RSOA-injected optical powers.