This PDF file contains the front matter associated with SPIE Proceedings Volume 10946, including the Title Page, Copyright information, Table of Contents, Introduction, and Author and Conference Committee lists

From subsea fiber cables to short-reach switch interconnects, optoelectronics is a key technology for hyperscale data center networks. As performance requirements increase, photonics moves deeper into the network replacing copper for shorter distances. The next move for photonics is to distances of less than 3m for in-rack applications. This talk will describe how the scale of data-bandwidth growth has challenged what is possible with traditional networks and where the next opportunities for innovation lie.

We present a scalable and novel modular optical metro core node architecture and low cost metro access node architectures with edge computing functionalities employing photonic WDM integrated switches. Photonic integrated switches has been des igned as the building blocks to realize the modular metro node architectures, namely photonic WDM switches with express and add/drop ports, photonic integrated WSS aggregation/disaggregation functions for merging/dropping the network traffic, and photonic integrated multi-cast switch (MCS), as well as bandwidth variable transceivers aggregators to achieve multi-Terabits/second operation. Moreover, a dynamic re-configurable metro-access nodes based on low-cost 2-degree photonic integrated mini-ROADMs will be discussed. The lossless photonic WDM switches are based on InP technology and employ semiconductor optical amplifiers as on -chip gain element and fast switch. The photonic WDM circuits allows to switch multiple format data signals in wavelength, space, and time for full flexibility, scalability of the interconnected network elements as well as capacity. Applications to data center interconnects and 5G will be discussed and experimental results reported.

The demand of ICT information capacity is increasing with unexpected rate, and it becomes extremely urgent issue for 400G and 1T class optical transceivers to put them in practical use. Not only high speed performance but also smaller form factor and lower power consumption capability is required, and therefore the development of the optical integration technology and the fine CMOS process are seriously examined. Under these critical situations, the forum standardization bodies such as IEEE802.3/OIF play important roles in the industry, and this paper reviews the latest status and its future estimated directions from the technical point of view.

This paper presents the integration of multiple silicon photonic (SiP) switches within a high-performance computing environment to enable network reconfigurability in order to achieve optimized bandwidth utilization. We demonstrate a physical testbed implementation that incorporates two fabricated SiP switches capable of switching traffic under real HPC benchmark workloads. The system uses dynamic optical bandwidth steering to match its physical network topology to the traffic characteristics of the application, and achieves up to approximately 40% reduction in application execution time of the high-performance computing benchmark. We present the detailed design of the network architecture and control plane of the system, and discuss the system performance improvements that arises from bandwidth-steering with silicon photonic-based circuit switching.

The use of vertical cavity surface emitting laser (VCSEL) at long wavelengths, especially if characterized by large bandwidth or tunable capability, is appearing as an attractive technology for the implementation of advanced transceivers to be used in optical metro networks at 100G and beyond.

In this work, we report recent promising results on the adoption of different types of VCSEL for the sliceable bandwidth/bitrate variable transceiver (S-BVT) design. Special attention will be devoted to technological aspects and challenges, focusing on the added value of exploiting novel photonic technologies for the implementation of costeffective transceivers, suitable for future optical metro networks targeting high capacity and flexibility.

The cost and complexity of future interconnects create a significant opportunity for emerging photonic tech- nologies such as fibers and switches. These technologies should be evaluated at the system level in order to determine the most efficient way they can be used, as well as provide feedback to photonic developers to better optimize for high-level impact. In this paper, we argue for the need for a systematic methodology to extract system-level models for any emerging photonic component. We then outline our past experience with extracting architectural-level metrics from device demonstrations and conducting architectural-level evaluations. Finally, we discuss qualities for a desirable solution to this problem that requires cross-community collaboration.

Real-time wavelength switching and routing at key access network nodes is an emerging fundamental functionality requirement for transparent content resolution and wavelength assignment towards better utilization of network resources under dynamic traffic patterns. In this paper, we experimentally demonstrate the first vertical cavity surface emitting laser (VCSEL)-based broadband switch for ultra-wide wavelength data traffic routing in Datacom. An 850 nm multimode VCSEL is directly modulated with 8.5 Gbps data and successfully transmitted error free over 100.3 m of OM3 multimode fibre link. At the integration node, the received data signal is used to drive a second VCSEL at 1550 nm, and forwarded over a second network link over 24.7 km of single mode fibre. We therefore achieve the first reported all-optical, real-time, inter-band wavelength switch to C-band. By exploiting wavelength tuneability, the 1550 nm VCSEL-based forwarding node is tuned to over 3.2 nm spectral range, for ultra-wide data routing over the second network link. A receiver sensitivity of -14.28 dBm of the converted signal is achieved at back-to-back analysis at the integration node. An additional penalty of 2.72 dB is introduced over the 24.7 km of single mode fibre transmission link. This work offers a viable enabling development technology for broadband wavelength converters for application real-time wavelength routing in the access network, to address content resolution and wavelength assignment problem for current and future Datacom.

Publisher's Note: This paper was published in error on 1 February 2019 by the publisher and was withdrawn on 15 March 2019. SPIE regrets this error.

We have developed an InAs/InP quantum dot (QD) mode-locked laser (MLL) with the channel spacing of 50 GHz. Its 3-dB bandwidth covering from 1546.89 nm to 1560.69 nm is 13.8 nm to provide 35 wavelength channels. We have investigated the relative intensity noises (RINs), phase noises, pulse duration and RF beating signals. By using this QD MLL we have successfully obtained the clear PAM-4 eye diagrams from any one of the filtered individual channels of the 50-GHz QD C-band MLL to demonstrate 2.24 Tbit/s (35x64 Gbit/s) PAM- 4 transmission bandwidth.

We present a symmetric-key direct data encryption technique utilizing signal masking by quantum noise, called Y-00 quantum stream cipher. Physical encryption of phase-shift-keying (PSK) Y-00 quantum stream cipher is achieved by our proposed extremely high-order phase modulation. Two cascaded phase modulators are driven with two synchronized digital-to-analog converters for coarse-to-fine modulations, resulting in a record 2¹⁷ phase levels for the quantum noise masking. Decryption of the cipher is implemented in digital signal processing after intra-dyne coherent detection with a free-running local oscillator. We experimentally demonstrate transmission of 10-Gbaud digital-coherent PSK Y-00 cipher with 2¹⁷ levels over a 240-km field-installed single-mode fiber.

Optical-path networks based on wavelength-selective switches (WSSs) can cost-effectively process wavelength-divisionmultiplexed (WDM) signals. To deal with the continuously increasing network traffic, the spectral efficiency must be improved by minimizing guardband bandwidths. Quasi-Nyquist WDM systems are seen as offering the highest spectral efficiency. However, such highly dense WDM systems suffer from signal-spectrum narrowing induced by the nonrectangular passbands of WSSs. Furthermore, widely deployed WSSs cannot process quasi-Nyquist WDM signals since the signal-alignment granularity does not match the passband resolution of the WSSs. In this paper, we propose a network architecture that enables quasi-Nyquist WDM networking. First, multiple channels are bundled so that the total channel bandwidth matches the WSS-passband resolution. Second, the number of spectrum-narrowing events of each path is limited by our restriction-aware algorithm. These proposals allow a 100-GHz bandwidth to accommodate three 100-Gbps DP-QPSK signals aligned with 33.3-GHz spacing and a 200-GHz bandwidth to accommodate three 400-Gbps dual-carrier DP-16QAM signals aligned with 66.6-GHz spacing. Intensive network analyses confirm that the spectral efficiency is improved by up to 46.4%. Feasibility is verified by transmission experiments using 69-channel 400-Gbps dual-carrier DP-16QAM signals aligned with 66.6-GHz spacing in the extended C-band. The fiber capacity of 27.6 Tbps and the transmission distance of 800 km are attained by our proposed quasi-Nyquist WDM networking.

The paper addresses the detection of malicious attacks targeting service disruption at the optical layer as a key prerequisite for fast and effective attack response and network recovery. We experimentally demonstrate the effects of signal insertion attacks with varying intensity in a real-life scenario. By applying data analytics tools, we analyze the properties of the obtained dataset to determine how the relationships among different optical performance monitoring (OPM) parameters of the signal change in the presence of an attack as opposed to the normal operating conditions. In addition, we evaluate the performance of an unsupervised learning technique, i.e., a clustering algorithm for anomaly detection, which can detect attacks as anomalies without prior knowledge of the attacks. We demonstrate the potential and the challenges of unsupervised learning for attack detection, propose guidelines for attack signature identification needed for the detection of the considered attack methods, and discuss remaining challenges related to optical network security.

We experimentally demonstrate a photonics-based radio-over-fiber orthogonal-frequency-division-multiplexing (ROFOFDM) system located within the terahertz-wave (THz-wave) frequency range from 350GHz to 510GHz. In our demonstrated system, 4.46-GHz-bandwidth OFDM quadrature-phases-shift-keying (OFDM-QPSK) THz-wave signal within the frequency range from 350GHz to 510GHz, can be generated and delivered over 2.5-inch wireless transmission distance, with a bit-error ratio (BER) under the hard-decision forward-error-correction (HD-FEC) threshold of 3.8×10-3. In our demonstrated system, 4.46-GHz-bandwidth OFDM-QPSK THz-wave signal at 450GHz is delivered over up to 35-km fiber transmission distance and 2.5-inch wireless transmission distance, with a BER of 3.8×10^-3.

Network slicing with Quality of Experience/Quality of Service (QoE/QoS) guarantees is seen as one of the key enablers of future 5G networks. Nevertheless, it poses several challenges in both resource provisioning and management that need to be addressed for the efficient end-to-end service delivery. In particular, network slice deployments considering operation across several domains and network segments, require of inter-domain configurations, continuous monitoring, potential actuations, inter-slice isolation, among other, in order to be provisioned and maintained, looking forward to guaranteeing their assured Key Performance Indicators (KPIs). In such scenario, optical networks are of prime importance, enabling the inter-connectivity between multiple far away segments and Points of Presence (PoPs). In light of this, in this paper we present an architecture design enabling network slice provisioning for 5G service chaining in multi-segment/multi-domain optical network scenarios. The presented design is enriched with a policy-based monitoring and actuation framework able to maintain the desired QoS for the provisioned end-to-end (E2E) network slice. We experimentally validated the proposal against real slice deployments and traffic generation, providing a proof of concept for the presented architecture, with special emphasis in the demonstration of the actuation framework as a key element for quality guarantees.

5G mobile networks will be utilized not only for mobile broadband services but also for other vertical sectors such as automotive, manufacturing and so on. Therefore, network operators are required to provide dedicated communication network services satisfying a variety of requirements. To realize that flexibly and quickly, technologies for constructing slices, which are dedicated virtual networks meeting each service’s requirements, are being widely studied. One crucial issue is the management and control of heterogeneous physical resources across the entire network. One key solution for addressing this is resource abstraction technology. It is important to adjust the resource abstraction level to achieve both reasonable resource allocations and efficient management. In this paper, we propose an abstracted resources model for mobile fronthaul and backhaul of 5G Radio Access Networks (RAN), and a method for abstracting resources from many types of physical network resource. Evaluation results show that the proposed method can reduce the processing step to half and enhance network efficiency.

Millimeter wave (mm-wave) and microwave frequency has become a hot research topic in recent years. Comparing to traditional wireless communication frequency, microwave possesses larger available bandwidth, which is up to tens of gigahertz, so that it can support advanced digital services with ultra-high bit rate. To support the transmission rate over 100Gbit/s in an optical wireless system, forward error correction (FEC) is adopted in real-time communication systems to correct bit errors. Polar code is a kind of FEC which can theoretically achieve channel capacity as the code length tends to infinity. In this paper, we experimentally demonstrate a photonics-aided microwave communication system at K-band. With polar coding, 20-Gbit/s signal is transmitted over 20m wireless link. Our experimental results show that BER performance of such optical wireless system can be improved largely after we employ polar coding.

The intensity modulation and direct detection (IM/DD) systems have been widely investigated and demonstrated to fulfil the requirement of short reach data communication links with simple implementation. DMLs are a low cost solution for IM/DD systems due to their low power dissipation, small footprint and high output optical power. However, for DMLs, the driving current can influence the optical density at its active region, hence the intrinsic chirp affects the generated optical carrier and results in distortions of the signals, which reduces transmission rates and signals decision accuracy. We propose a machine learning-based decision technique to mitigate nonlinear distortions of the DMLs without using any nonlinear processing, and demonstrate a 60-Gb/s PAM-8 IM/DD system using a DML. About 0.6-dB receiver sensitivity improvement is achieved after 2km transmission.

With the popularization of data center and other bandwidth hungry inter-connect applications, the desired capacity of short reach optical network has exponentially increased. In order to realize high-speed transmission, a few modulation formats or schemes, such as PAM4 and DMT are proposed and experimentally demonstrated. However, these modulation formats need expensive DAC and ADC as well as DSP procession. OOK modulation has simple architecture and high receiver sensitivity. Duo-binary signal is a special OOK signal. Here we experimentally demonstrate a record bit rate of 160-Gb/s OOK electrical signal generation, and realize a duobinary optical signal at a bit rate of 160Gb/s transmission and detection.

A significant amount of R&D effort has been expended recently in finding Shannon capacity-approaching modulation schemes for optical communications. Probabilistic shaping (PS) of QAM constellations has emerged as a particularly attractive solution, allowing fine-grain adjustment of bit-loading, which can be traded off for transmission reach; this approach is ideal for realizing flexible, bandwidth-variable transceivers. PS-QAM, as well as other techniques such as digital subcarrier multiplexing (DSCM), pose significant challenges for the design of transceivers. In particular, the resolution of the digital-to-analog and analog-to-digital converters (DACs/ADCs) becomes critical, if the full benefits of advanced formats are to be obtained.

We present results of our investigation on applying intentionally nonuniform quantization in optical transceivers, as a means of relaxing DAC resolution requirements. By matching the quantizer’s transfer function to the distribution of the signal amplitudes, quantization noise can be minimized. This novel approach can lower component cost and power consumption, potentially bringing advanced modulation formats to short-haul/metro links. Moreover, transceivers in the less cost-sensitive long-haul market segment can also profit from increased performance, due to higher signal-toquantization noise ratio (SQNR). We show how to derive the nonuniform levels for any given modulation format, and quantify by means of extensive simulations the performance gain of the overall coherent system.

In this paper, a study of the influence and compensation of electroabsorption and Mach-Zehnder modulator non-linarites is made for the PAM-4, PAM-5 and PAM-8 modulation formats. The compensation is made with a level adjustment by a digital to analog converter (DAC) for which number of bits exceeds the minimal requirements for evaluated modulation schemes. As figures of merit, the level distribution and eye-opening corresponding to each level is used. The results show that compensation increases the signal quality by leveraging the modulator’s static extinction ratio.

We have developed a semiconductor optical amplifier (SOA) based incoherent light source for a co-propagating distributed Raman amplifier. By utilizing the incoherent light source as a 1st-order pump of the Raman amplifier, we have experimentally verified the reduction of RIN transfer regardless of the presence of simultaneous amplification by 2nd-order coherent pumps. In addition, improved Q-factor has been demonstrated by 22.5 Gbaud polarization-division multiplexing 16 quadrature amplitude modulation (PDM-16QAM) transmission experiment over 2720 km in a re-circulating fiber loop. From subsequent experimental study, we have redesigned wavelength shifted 1st-order incoherent pump and measured at Raman gains in L-band wavelength.

In this paper an intermediate solution to pulse amplitude modulation with 4 levels (PAM-4) and PAM-8, namely PAM-6 is presented. The generation of the signal is based on a constellation from 32-quadrature amplitude modulation (32-QAM) and assumes the I and Q components to be interleaved, which allows its application in intensity modulation/direct detection systems. The PAM-6 modulation shows higher resistance to noise than PAM-8 and increased by 25% the bitrate for constant bandwidth when compared to PAM-4. In the paper, experimental results and a comparison of PAM-6 modulation to PAM-4 and PAM-8 is made for an electrical interface, a directly modulated 850nm VCSEL and an externally modulated 1310nm DFB laser.

Advanced metro-access WDM optical fibre telecommunication networks employ integrated wavelength switching nodes to provide efficient, flexible wavelength allocation along the link. Recent developments, together with the increase in bandwidth intense applications, have sparked great interest in flexible, grid-like optical network systems. Flexible spectrum optical network systems with non-static channel bandwidth, wavelength allocation, switching and routing permit the optimum distribution of data with variable rates and modulation formats. This paper describes a unique technique for all-optical wavelength reservation at a forwarding flex spectrum node. The outgoing signal is locked to the incoming signal at the node, thereby guaranteeing automatic wavelength reservation and allocation. A saturated EDFA is used to erase data from the incoming signal, which is then used to lock the wavelength of the forwarding node through VCSEL injection. The EDFA is shown to reduce the extinction ratio of the incoming signal from 7.3 dB to less than 1 dB (560 mdB). We show automatic wavelength reservation over 1.68 nm within the C-band, with 25.5 km transmission over G. 655 single mode fibre. Considering 50 GHz per-channel bandwidth allocations, this technique translates to 4-channel operation in a typical metro-access type configuration.

The exponential growth of data traffic in current optical communication networks require higher capacity for the bandwidth demands at a reduced cost per bit. All-optical signal processing is a promising technique to improve network resource utilization and resolve wavelength contention associated with flexible spectrum. This is achieved without necessarily employing optical to electrical signal conversions. In this paper, we experimentally present a novel, spectral efficient technique for defragmentation and wavelength switching on a cascade of vertical cavity surface emitting lasers (VCSELs). This is based on cross gain modulation of the optical transmitter. A 10 Gbps intensity modulated master VCSEL lasing at 1549 nm was used for optical power injection into the side modes of two slave VCSELs. The injection results in energy transfer between the lasing modes, causing data inversion on the transmission wavelength. The master lasing wavelength was tuned from 1546.5 to 1551.7 nm resulting in a 5.2 nm or 650 GHz spectral width by varying the bias current. A total of 9 continuous 50 GHz spaced WDM channels with nonoverlapping nominal frequencies and uniform guard bands were generated. This can be used to attain seamless defragmentation and bandwidth optimization for effective spectral resource management. The novel technique is flexible in terms of modulation formats and accommodates various formats with spectrally continuous channels, thereby fulfilling the future bandwidth demands with transmissions beyond 100 Gbps per channel while maintaining spectral efficiency.

This is an invited paper - 250-word abstract is not required.