Showing papers by "Ciena published in 2017"

Beyond 100 Gb/s: capacity, flexibility, and network optimization [Invited]

Abstract: In this paper, we discuss building blocks that enable the exploitation of optical capacities beyond 100 Gb∕s. Optical networks will benefit from more flexibility and agility in their network elements, especially from coherent transceivers. To achieve capacities of 400 Gb∕s and more, coherent transceivers will operate at higher symbol rates. This will be made possible with higher bandwidth components using new electro-optic technologies implemented with indium phosphide and silicon photonics. Digital signal processing will benefit from new algorithms. Multi-dimensional modulation, of which some formats are already in existence in current flexible coherent transceivers, will provide improved tolerance to noise and fiber nonlinearities. Constellation shaping will further improve these tolerances while allowing a finer granularity in the selection of capacity. Frequency-division multiplexing will also provide improved tolerance to the nonlinear characteristics of fibers. Algorithms with reduced computation complexity will allow the implementation, at speeds, of direct pre-compensation of nonlinear propagation effects. Advancement in forward error correction will shrink the performance gap with Shannon’s limit. At the network control and management level, new tools are being developed to achieve a more efficient utilization of networks. This will also allow for network virtualization, orchestration, and management. Finally, FlexEthernet and FlexOTN will be put in place to allow network operators to optimize capacity in their optical transport networks without manual changes to the client hardware.

Channel Power Optimization of WDM Systems Following Gaussian Noise Nonlinearity Model in Presence of Stimulated Raman Scattering

Abstract: The impact of interchannel stimulated Raman scattering (SRS) on optimization of channel powers to maximize the minimum channel margin is examined using a discrete Gaussian noise model for the Kerr nonlinearity. The simultaneous consideration of these two nonlinear effects is found to be incompatible with the goal of a convex SNR expression that can be optimized globally. A sequence of convex optimizations is employed to obtain a locally optimal solution, along with a bound on the degree of suboptimality. Optimization results obtained are most accurate for Gaussian-distributed signals, such as probabilistically shaped high-order-modulated signals. In a dispersion-uncompensated 4000-km fiber system utilizing the full C -band with perfect per-span SRS gain compensation, power optimization yields benefits of 0.25 to 2 dB over optimal spectrally flat power allocations. In systems including both C- and L -band, an optimization method that accounts for both SRS and Kerr nonlinearity effects provides a 0.23 to 0.60 dB margin benefit over a method compensating for SRS gain alone. In a system spanning only the C -band, per-span SRS gain compensation is not critical, as the maximum benefit is a 0.14 dB gain in minimum margin for optimized power allocations. By contrast, in a system spanning both C- and L -band, per-span SRS gain compensation provides a gain of up to 1.23 dB with optimized power allocations and larger gains with suboptimal power allocations.

Linear Large-Swing Push–Pull SiGe BiCMOS Drivers for Silicon Photonics Modulators

Abstract: The analysis, design, and experimental characterization of a novel class of large-swing low output-impedance push-pull SiGe BiCMOS drivers are discussed. The circuits, which employ single- and series-stacked emitter follower (EF) and MOS-HBT cascode topologies, are intended to drive optical modulators with high-order m-pulse-amplitude modulated (PAM) signals, while maximizing energy/bit efficiency. The series-stacked EF version, implemented in a 55-nm SiGe BiCMOS technology with 370 GHz ${f_{\mathrm {MAX}}}$ , achieved the highest linearity with 4.8-Vpp differential output swing, 57.5 GHz bandwidth, and an output compression point of 12 dBm per side. Four-PAM and eight-PAM eye diagrams were measured at 56 GBd for a record data rate of 168 Gb/s. Four-PAM 64-GBd eye diagrams were also demonstrated. The circuit consumes 820/600 mW with/without the predriver and has an energy efficiency of 4.88/3.57 pJ/b.

Fiber Nonlinear Noise-to-Signal Ratio Monitoring Using Artificial Neural Networks

Abstract: An artificial neural network model to estimate fiber nonlinear noise-to-signal ratio based on amplitude noise covariance of received symbols is proposed. Standard deviation of 0.2 dB is obtained in simulation, and estimation error of <0.6 dB is verified in experiment.

SiGe BiCMOS linear modulator drivers with 4.8-V pp differential output swing for 120-GBaud applications

Abstract: Two linear, large-swing distributed amplifiers (DAs) are reported for future 120-GBaud fiber-optic systems. The measured differential gain and bandwidth are over 20 dB and 70 GHz, respectively, and the P 1dB is −2.5 dBm. Eye diagram measurements with at least 4.8-V pp differential swing were performed for NRZ signals up to a record 120 Gb/s, and with 4-PAM and 8-PAM signals up to 64 GBaud, with the symbol rate limited by the speed and ENOB of the arbitrary waveform generator. As well, a bit error rate better than 10−12 is demonstrated at 64 Gb/s.

Probabilistic Design of Optical Transmission Systems

Abstract: Traditionally, optical fiber nonlinearity is considered a limiting factor for transmission systems. Nevertheless, from a system design perspective this nonlinearity can be exploited to minimize the impact of uncertainty on the system performance. A consequence of this is that it becomes beneficial to consider the uncertainty at the design stage, resulting in a probabilistic design, rather than conventional design approaches whereby uncertainty is added by way of system margins to a deterministic design. In this paper, we conduct extensive experimental measurements to quantify the impact of uncertainty for a multispan wavelength division multiplexed system transmitting 100 GbE or 200 GbE as dual polarization quadrature phase-shift keying (QPSK) or 16 quadrature amplitude modulation (16QAM), respectively. The impact of uncertainty in the power launched into a span is assessed for a 10 × 80 km link. For dual polarization (DP)-QPSK, the intralink power deviation with the probabilistic design with 100% reliability is $\pm$ 1.3 dB falling to 99% reliability with $\pm$ 1.6 dB. In contrast, for DP-16QAM maximum deviation for 100% reliability is $\pm$ 0.5 dB falling to 99% for $\pm$ 0.6 dB. Following this, we consider the interplay between polarization dependent loss (PDL) and fiber nonlinearity over an 8 $\times$ 80 km system again for both DP-QPSK and DP-16QAM. A system Q variation of less than 0.15 dB due to the interaction between PDL and fiber nonlinearity is observed for 99.9% of examined PDL values for DP-QPSK and DP-16QAM, thereby allowing the two effects to be considered separately.

Nonlinear Compensation in Optical Communications Systems With Normal Dispersion Fibers Using the Nonlinear Fourier Transform

Abstract: We investigate the computational cost of the nonlinear Fourier transform (NFT) based on the Zakharov–Shabat scattering problem as a nonlinear compensation technique for quadrature-phase-shift keyed (QPSK) signals with raised cosine frequency characteristic in optical fiber transmission systems with normal dispersion fibers. We show that the primary sources of computational errors that arise from the use of the NFT is the finite eigenvalue resolution of the left and the right reflection spectra. We show that this effect and, consequently, the computational cost of the NFT as a nonlinear mitigation technique in the normal dispersion regime increases exponentially or faster with both the channel power and the number of symbols per data frame even using the most efficient NFT algorithms that are currently known. We find that the computational cost of this approach becomes unacceptably large at data frame lengths and powers that are too small for this approach to be competitive with standard transmission methods. We explain the physical reasons for these limits.

Phase noise characterization of a QD-based diode laser frequency comb

Abstract: We measure, simultaneously, the phases of a large set of comb lines from a passively mode locked, InAs/InP, quantum dot laser frequency comb (QDLFC) by comparing the lines to a stable comb reference using multi-heterodyne coherent detection. Simultaneity permits the separation of differential and common mode phase noise and a straightforward determination of the wavelength corresponding to the minimum width of the comb line. We find that the common mode and differential phases are uncorrelated, and measure for the first time for a QDLFC that the intrinsic differential-mode phase (IDMP) between adjacent subcarriers is substantially the same for all subcarrier pairs. The latter observation supports an interpretation of 4.4ps as the standard deviation of IDMP on a 200µs time interval for this laser.

Optimized virtual network function service chaining with hardware acceleration

Abstract: Systems and methods for Virtual Network Function (VNF) service chain optimization include, responsive to a request, determining placement for one or more VNFs in a VNF service chain based on a lowest cost determination; configuring at least one programmable region of acceleration hardware for at least one VNF of the one or more VNFs; and activating the VNF service chain. The lowest cost determination can be based on a service chain cost model that assigns costs based on connectivity between switching elements and between hops between sites. The activating can include a Make-Before-Break (MBB) operation in a network to minimize service interruption of the VNF service chain.

Agile filterless optical networking

Abstract: Filterless optical networks based on broadcast-and-select nodes equipped with coherent transceivers can be considered as very attractive solutions for cost-effective and flexible capacity allocation in terrestrial and submarine applications. In this paper, we present an overview of the research on filterless optical networking in the last 10 years.

770-Gb/s PDM-32QAM Coherent Transmission Using InP Dual Polarization IQ Modulator

Abstract: We experimentally demonstrate 770-Gb/s (77-Gbd PDM-32QAM) transmission on a single wavelength using an indium phosphide dual polarization IQ modulator over 320 km of standard single mode fiber, which is suitable for low-cost metro networks and datacenter interconnects. Moreover with the same setup, we also demonstrate transmissions of 84-Gbd polarization division multiplexed (PDM)-16QAM and 84-Gbd PDM-8QAM signals over 960 and 1980 km distances, respectively, for regional and long-haul networks.

57.5GHz bandwidth 4.8Vp p swing linear modulator driver for 64GBaud m-PAM systems

Abstract: A novel series-stacked large swing push-pull MOS-HBT driver was implemented in 55nm SiGe BiCMOS technology. The circuit achieves 4.8Vpp differential swing, 57.5GHz band-width and has an output compression point of 12 dBm per side. 4-PAM and 8-PAM eye diagrams were measured at 56 GBaud for a record data rate of 168 Gb/s. 4-PAM 64GBaud eye diagrams were also demonstrated. The circuit consumes 820/600 mW with/without the predriver, for an energy efficiency of 4.88/3.57 pJ/b.

DC-62 GHz 4-phase 25% duty cycle quadrature clock generator

Abstract: A process-, temperature-and supply-insensitive DC-to-62GHz 4-phase quadrature generator for clock signals with 25% duty cycle was manufactured in a production 55-nm SiGe BiCMOS technology. The purely digital circuit is based on a 2.5 V bipolar-CML static divider, AND gates and inverter stages, and operates with input signals from DC to 124 GHz while consuming 178 mW. Measurements were conducted with 63-GHz and 100-GHz bandwidth real-time oscilloscopes. The measured self-oscillation frequency of the static divider in the generator was 98.8 GHz, compared to 93 GHz in simulation. The measured output signals remained in quadrature up to 62 GHz. The measured duty cycle is 25–26% up to 30 GHz and increases up to 33% at 50 GHz, beyond which measurements are impacted by the limited bandwidth of the oscilloscope. The simulated duty cycle was lower than 28% up to 62 GHz.

280-Gb/s 320-km transmission of polarization-division multiplexed QAM-PAM with stokes vector receiver

Abstract: We propose a novel three-dimensional modulation scheme on Stokes space for metro and regional optical transmissions. Based on this scheme, 320-km transmission of 280-Gb/s 160AM-PAM2 signals using a Stokes vector receiver is experimentally demonstrated.

Flexible Ethernet chip-to-chip inteface systems and methods

Abstract: A Chip-to-Chip (C2C) interface utilizing Flexible Ethernet (FlexE) includes circuitry configured to provide a packet interface on a single card or over backplane/fabric links between two devices, wherein the circuitry comprises flow control and channelization for the FlexE. Each of the two devices can include any of a Network Processor (NPU), a Fabric Interface Card (FIC), a framer, and a mapper. A rate of the FlexE can be increased to support additional information for the flow control and the channelization.

Use of Extreme Value Statistics to Assess the Performance Implications of Cascaded ROADMs

Abstract: The performance implications of passband impairments and bandwidth narrowing caused by the cascading of optical filters are investigated using a 100 Gb/s dual polarization, quadrature-phase-shift-keyed (DP QPSK) transceiver. The overall responses for cascades of filters are emulated using the combination of a programmable optical filter and variable bandwidth optical filter. The statistical variations in the responses for a cascade are addressed by considering 1000 realizations that result from randomly selected responses for each of the individual filters. To determine the impact on system margins, a methodology based on extreme value statistics is presented. The signal-to-noise ratios (SNRs) that correspond to real-time estimates of the pre-forward error correction bit error ratio (pre-FEC BER) are quantified in terms of the probability that the minimum of $n$ observations of the SNR is less than a specified value (maximum pre-FEC BER exceeds a specified value). This approach improves the reliability of predicting the impact of cascaded filtering on system performance by removing the uncertainty about the underlying statistical distribution of the SNR.

Methods and apparatus for pre-programming layer-0 service turn up speeds for photonic service provisioning or restoration

Abstract: Pre-programming Layer-0 optical protection path restoration speeds is provided based on available path margin. Higher layer routers and switches can be made aware of the expected Layer-0 restoration time, and their switch time can be programmed accordingly. The proposed method can provide users an option to program a restoration speed for a specific photonic service on a per restoration path basis. The method can highlight which services will potentially be impacted by the selected restoration speed on that path. The user can proceed with the selected speed for restoring high priority layer-0 services even if that means the fast restoring event can potentially impact other low priority services already in-service on the restoration path.

Artificial Neural Networks for Fiber Nonlinear Noise Estimation

Abstract: OSNR monitoring techniques are reviewed and a use of machine learning to estimate the nonlinear noise and thereby monitor the OSNR is described. High monitoring accuracy is demonstrated for a wide range of link conditions using an artificial neural network.

Optical modulator with improved efficiency

Abstract: An optical modulator circuit includes first and second electrodes, first and second p-n junction segments (PNJSs), and first and second optical waveguides. The first PNJS includes a first modulating p-n junction (MPNJ) in series with a first non-modulating device (NMD) that are connected to the first and second electrodes, respectively, where the first NMD includes a first substantially larger capacitance than the first MPNJ. The second PNJS includes a second NMD in series with a second MPNJ that are connected to the first and second electrodes, respectively, where the second NMD includes a second substantially larger capacitance than the second MPNJ. The first and second optical waveguides superimpose the first and second MPNJs, respectively, where the first and second MPNJs are configured to modulate a refractive index of the first and second optical waveguides, respectively, based on the substantially larger capacitance of the first NMD and the second NMD.

Resource Savings in Submarine Networks Using Agility of Filterless Architectures

Abstract: Filterless submarine networks based on broadcast-and-select nodes equipped with coherent transceivers are promising solutions for flexible capacity allocation. This letter shows how the agility allowed by filterless architectures can save resources through lightpath reconfiguration in subsea networks.

Dynamic adjustment of connection priority in networks

Abstract: Systems and methods for dynamic adjustment of a connection's priority in a network include configuring the connection with a dynamic priority and setting a current priority based on one or more factors, wherein the connection is a Layer 0 connection, a Layer 1 connection, and a combination thereof; detecting an event in the network requiring a change to the current priority, wherein the event changes the one or more factors; and causing a change in the current priority of the connection based on the event.

Optical clock recovery using feedback phase rotator with non-linear compensation

Abstract: A method for clock recovery that may include obtaining an output signal from a phase locked loop (PLL) device. The method may further include determining, using a digital phase detector, the output signal, and a transmitter clock signal, an amount of phase difference between the output signal and the transmitter clock signal. The method may further include filtering, using a phase rotator and a digital accumulator, a portion of the amount of phase difference from the output signal to generate a filtered signal.

Systems and methods for modular deployment and upgrade of multiple optical spectrum bands in optical transmission systems

Abstract: An optical node supporting a modular deployment and upgrade of optical spectrum includes one or more C+L-Band amplifier modules; and a modular base module configured to interface one or more C-Band optical modems; wherein, in an initial deployment configuration, the modular base module provides channelized Amplified Spontaneous Emission (ASE) loading for select channels in the C-Band via a first ASE noise source coupled to a multiplexer for the C-Band, bulk ASE loading over the L-Band via a second ASE noise source coupled to an L-Band output, and an upgrade port for connection to an L-Band upgrade module The L-Band upgrade module can selectively connect to the upgrade port to provide an L-Band upgrade configuration where the L-Band upgrade module and the modular base module coordinate transition of the bulk ASE loading to L-Band channelized ASE loading via a third ASE noise source

Touch and pressure sensitive surface with haptic methods for blind probe alignment

Abstract: A method may include detecting a position of a first probe based on a placement of the first probe relative to a first zone on a surface of a device, obtaining a first target position for the first probe in the first zone, comparing the position of the first probe to the first target position, and generating a first haptic response to guide the first probe toward the first target position when the position of the first probe is outside a first predetermined tolerance relative to the first target position. The first haptic response may vary with the position of the first probe.

High capacity coherent optical transceiver for short reach applications

Abstract: An optical transceiver includes a transmitter including transmitter signal processing circuitry configured to receive a transmit signal and provide two drive voltage signals V 1 , V 2 to a modulator configured to modulate a laser based thereon; and a receiver including i) optical couplers configured to coherently combine received signals with a Local Oscillator (LO) formed by the laser and provide the combined signals to photodetectors for balanced detection, and ii) receiver signal processing circuitry configured to demodulate outputs from the balanced detection, wherein the receiver signal processing circuitry comprises an analog front-end and digital back-end.

Virtualized sections for sectional control of optical links

Abstract: Systems and methods are implemented at an Optical Add/Drop Multiplexer (OADM) node using virtual sections to provide sectional control over an optical link over a foreign-controlled optical network. The systems and methods include virtually splitting the optical link at a shelf processor associated with the OADM node; in a non-fault condition, obtaining and storing a power snapshot of the optical link and associated virtual sections thereon, from an optical spectrum monitor; responsive to a fault on one or more virtual sections of the virtual sections, obtaining a current power snapshot of the optical link and the associated virtual sections; and comparing the stored power snapshot and the current power snapshot of the one or more virtual sections and providing a fault alarm for the one or more virtual sections based on the comparing to a control plane for management thereof.

Power Control in an Optical Fiber Network

Abstract: Multiple receivers are comprised in a flexible coherent transceiver of a multi-span optical fiber network. Each of the multiple receivers is operative to handle communications on a respective channel. The multiple receivers measure optical characteristics. For each of the multiple receivers, the optical characteristics include optical nonlinear interactions on the respective channel, the optical nonlinear interactions being at least partially dependent from one span to another span. An optical power of a signal on each of the multiple channels is adjusted as a function of the optical characteristics.

Adjustment of control parameters of section of optical fiber network

Abstract: A processor of an apparatus is configured to apply one or more control algorithms using estimated data to adjust the one or more control parameters of a section of an optical fiber network. The estimated data are derived from measurements of optical signals in the section and from knowledge of the section. The estimated data is a function of optical nonlinearity and of amplified spontaneous emission.

Fiber kerr nonlinear noise estimation

Abstract: A method of fiber Kerr nonlinear noise estimation in an optical transmission system comprises recovering received symbols from a received signal, isolating a noise component of the received signal, estimating coefficients of a matrix based on cross-correlations between the isolated noise component and the fields of a triplet of received symbols or training symbols or estimated transmitted symbols, estimating doublet correlations of the product or the quotient of the isolated noise component and the field of a received symbol or of a training symbol or of an estimated transmitted symbol, and estimating one or more parameters related to nonlinear noise based on the estimated coefficients of the matrix and based on the estimated doublet correlations.

Port congestion resiliency in a multi-card and multi-switch link aggregation group

Abstract: Systems and methods for port congestion resiliency in a Link Aggregation Group (LAG) including a multi-card LAG and/or a multi-switch LAG. A method includes receiving a packet for egress over the LAG; responsive to determining no congestion over internal ports not part of the LAG, hashing with all member ports in the LAG in a distribution state; and, responsive to determining congestion over the internal ports, hashing with only member ports on a local card in which the packet was received, wherein the hashing determines which member port the packet egresses from in the LAG. The multi-card LAG includes multiple cards where packets ingress and egress from, and the cards communicate via a backplane port which is not part of the LAG. The multi-switch LAG includes multiple chassis where packets ingress and egress from, and the chassis communicate via an inter-switch connectivity port which is not part of the LAG.