Showing papers by "Infinera published in 2020"

800G DSP ASIC Design Using Probabilistic Shaping and Digital Sub-Carrier Multiplexing

Abstract: The design of application-specific integrated circuits (ASIC) is at the core of modern ultra-high-speed transponders employing advanced digital signal processing (DSP) algorithms. This manuscript discusses the motivations for jointly utilizing transmission techniques such as probabilistic shaping and digital sub-carrier multiplexing in digital coherent optical transmissions systems. First, we describe the key-building blocks of modern high-speed DSP-based transponders working at up to 800G per wave. Second, we show the benefits of these transmission methods in terms of system level performance. Finally, we report, to the best of our knowledge, the first long-haul experimental transmission – e.g., over 1000 km – with a real-time 7 nm DSP ASIC and digital coherent optics (DCO) capable of data rates up to 1.6 Tb/s using two waves (2 × 800G).

200 Gbps/Lane IM/DD Technologies for Short Reach Optical Interconnects

Abstract: Client-side optics are facing an ever-increasing upgrading pace, driven by upcoming 5G related services and datacenter applications. The demand for a single lane data rate is soon approaching 200 Gbps. To meet such high-speed requirement, all segments of traditional intensity modulation direct detection (IM/DD) technologies are being challenged. The characteristics of electrical and optoelectronic components and the performance of modulation, coding, and digital signal processing (DSP) techniques are being stretched to their limits. In this context, we witnessed technological breakthroughs in several aspects, including development of broadband devices, novel modulation formats and coding, and high-performance DSP algorithms for the past few years. A great momentum has been accumulated to overcome the aforementioned challenges. In this article, we focus on IM/DD transmissions, and provide an overview of recent research and development efforts on key enabling technologies for 200 Gbps per lane and beyond. Our recent demonstrations of 200 Gbps short-reach transmissions with 4-level pulse amplitude modulation (PAM) and discrete multitone signals are also presented as examples to show the system requirements in terms of device characteristics and DSP performance. Apart from digital coherent technologies and advanced direct detection systems, such as Stokes–vector and Kramers–Kronig schemes, we expect high-speed IM/DD systems will remain advantageous in terms of system cost, power consumption, and footprint for short reach applications in the short- to mid- term perspective.

CAPEX Savings Enabled by Point-to-Multipoint Coherent Pluggable Optics Using Digital Subcarrier Multiplexing in Metro Aggregation Networks

Abstract: Acknowledging the predominantly hubbed traffic profile in the metro, we apply digital subcarrier multiplexing techniques to 400Gb/s coherent pluggable optics, enabling a point-to-multipoint architecture which shows TCO savings of 76% over a five-year period compared to a traditional architecture based on ROADMs and point-to-point transponder

Optimized Design and Challenges for C&L Band Optical Line Systems

Abstract: Optical communications are the key enabler for the ever-increasing traffic growth as they allow multiplexing a number of carriers onto a single optical fiber. However, network deployments are becoming more challenging due to the large bandwidth increments. Indeed, the fiber planning process is a slow, costly, and strategic activity for network operators, who must decide where to rent or deploy additional capacity. Depending on the long-term view, the network operator will define a fiber plan which may require high capital expenditure (CAPEX) investments to deploy additional multiple fiber pairs between central offices. During the last few years, C&L-band technologies have evolved to a point where they are now strong candidates to extend the fiber lifetime of these high capacity links. This article aims to present the evolution of C&L-band systems from a network design perspective, covering transmission and optical amplifier capabilities, demand optimization phase, showing a record demonstration of 56.4 Tb/s C&L-band 800 km transmission using commercial C&L-band system technology.

1.6Tbps Coherent 2-Channel Transceiver using a Monolithic Tx/Rx InP PIC and Single SiGe ASIC

Abstract: We present a 1.6Tbps coherent transceiver delivering 800Gbps/wave transmission using integrated Tx/Rx functions with 50GHz bandwidth and 50kHz linewidth tunable lasers on a single 2-channel InP PIC, paired with a SiGe Driver and TIA ASIC.

Real-Time Demonstration of 2.4Tbps (200Gbps/λ) Bidirectional Coherent DWDM-PON Enabled by Coherent Nyquist Subcarriers

Abstract: We demonstrate real-time 2.4Tbps bidirectional coherent DWDM-PON (12λ×200Gbps/λ) over 100km SMF, enabled by multiplexing Nyquist subcarriers. Further, through proof-of-concept experiments, we show the advantage of coherent subcarrier aggregation in next-generation point-to-multipoint bidirectional access networks.

A Monolithically Integrated Racetrack Colliding-Pulse Mode-Locked Laser With Pulse-Picking Modulator

Abstract: We present a novel photonic integrated circuit (PIC) that monolithically integrates a racetrack colliding-pulse mode-locked laser with a pulse-picking electro-absorption modulator and a semiconductor optical amplifier on Indium Phosphide. We present detailed characterization of this PIC that includes optical pulse characterization, phase noise and long term stability under passive and hybrid mode-locking conditions. Allan deviation measurements made on the optical pulse train from the PIC show a fractional frequency instability of $8\times 10 ^{-11}$ at 1 second and follow a 1/ $\tau $ trend. We also demonstrate repetition rate reduction from ~10 GHz to ~500 MHz with an extinction ratio of ~14.65 dB using an on-chip pulse-picking electro-absorption modulator.

Improved Jitter Distribution Tail-Fitting Algorithm for Decomposition of Random and Deterministic Jitter

Abstract: An improved method for decomposition of random and deterministic jitter measurements using tail fitting of the probability density function of total jitter is proposed. The currently employed techniques assume that the tails of the probability density function tend to a Gaussian function. We show that to be inaccurate by deriving analytical expressions for the accurate asymptotic form of the probability density and cumulative distribution functions. In doing so, we prove that the tails approach a Gaussian function multiplied by a term that is inversely proportional to the total jitter. Monte Carlo simulations of jitter consisting of a combination of random and deterministic components are performed and nonlinear least squares fits to the derived asymptotic forms are used to estimate the root mean square of the random component and the bounds of the deterministic component for a few examples.

Recent advances in stabilization of mode-locked quantum dash lasers at 1.55 µm by dual-loop optical feedback

Abstract: This paper reports the effectiveness of a variety of single- and dual-loop optical feedback arrangements on stability of self-mode-locked two-section quantum dash lasers emitting at ≈1.55 µm and operating at 21 GHz repetition rate. We describe reduction of RF linewidth and timing jitter using five distinct schemes, including single and dual loops with symmetric and asymmetric lengths, and with balanced and unbalanced feedback ratios. All feedback schemes described are effective in stabilizing the pulse trains from SML QDash lasers, but some require precisely tuned resonance between loop delay and laser cavity. We show balanced asymmetric dual-loop optical feedback is the most robust, cost-effective and low-noise method to stabilize and control pulses from mode-locked lasers and optoelectronic oscillators.

Demonstration of Extensible Threshold-Based Streaming Telemetry for Open DWDM Analytics and Verification

Abstract: A novel and practical threshold-based extension of streaming telemetry that advances open WDM analytics and introduces network verification, is demonstrated employing an extensible NOS application agent combined with standard NETCONF/YANG and open-source software technologies.

Record Ultra-High Full-Fill Capacity Trans-Atlantic Submarine Deployment Ushering in the SDM Era

Abstract: A record capacity of 24 Tbps on a 6,644 km trans-Atlantic deployment using 16QAM is enabled by synthesized subcarriers, FEC gain sharing, multi-carrier wavelocking, and large-area, high dispersion fiber. Computer assisted optimization and automated protection facilitate full-fill deployments becoming prevalent as submarine cables enter the SDM era.

Modulation format dependence on transmission reach in phase-sensitively amplified fiber links.

Abstract: We quantify the maximum transmission reach for phase-insensitive amplifier (PIA) and phase-sensitive amplifier (PSA) links with different modulation formats and show that the maximum transmission reach increase (MTRI) when using PSAs compared to PIAs is enhanced for higher-order modulation formats. The higher-order modulation formats are more susceptible to smaller phase rotations from nonlinearities, and PSAs are efficient in mitigating these smaller phase distortions. Numerical simulations were performed for single- and multi-span PIA and PSA links with single and multiple wavelength channels. We obtain a significant enhancement in the MTRI with PSAs compared to PIAs when using higher-order modulation formats for both the single- and multi-channel systems in single- and multi-span links. We verify the enhancement with a single-span, single-channel system experiment. We also demonstrate, for the first time, a 64-QAM modulation format fiber transmission in phase-sensitively amplified link, with a 13.3-dB maximum allowable span loss increase compared to a phase-insensitively amplified link.

Individually routable digital subcarriers

Abstract: Consistent with an aspect of the present disclosure, electrical signals or digital subcarriers are generated in a DSP based on independent input data streams. Drive signals are generated based on the digital subcarriers, and such drive signals are applied to an optical modulator, including, for example, a Mach-Zehnder modulator. The optical modulator modulates light output from a laser based on the drive signals to supply optical subcarriers corresponding to the digital subcarriers. These optical subcarriers may be received by optical receivers provided at different locations in an optical communications network, where the optical subcarrier may be processed, and the input data stream associated with such optical subcarrier is output. Accordingly, instead of providing multiple lasers and modulators, for example, data is carried by individual subcarriers output from an optical source including one laser and modulator. Thus, a cost associated with the network may be reduced. Moreover, each of the subcarriers may be detected by a corresponding one of a plurality of receivers, each of which being provided in a different location in the optical communication network. Thus, receivers need not be co-located, such that the network has improved flexibility.

System innovations in open WDM DCI networks

Abstract: We review the most important WDM system innovations motivated by the evolution of DCI transport. State-of-the-art coherent transmission has already exceeded 6 b/s/Hz in transatlantic deployments. Moreover, the adoption of software innovations in automation and programmability, which DCI pioneered in transport networks, has also simplified operations and enables the emergence of open transport architectures. Combining these advances with emerging network analytic frameworks allows exciting innovations in network design and management optimization.

$2\times 800$ Gbps/wave Coherent Optical Module Using a Monolithic InP Transceiver PIC

Abstract: We report on the development of a $2\times 800$ Gbps/wave coherent module based on a monolithic InP transceiver PIC and real-time 7nm DSP ASIC capable of 800Gbps data transmission over record 1000km SMF-28 link using a 96Gbaud, PCS-64QAM modulation format.

Method and system to synchronize remote defect signaling and wavelength selective switch controls

Abstract: A system and method is disclosed in which circuitry of a first controller of a first node on a first path within a transport network receives a first signal indicating a failure within the first path from a second controller. The first node is an end node of the first path. A first client signal failure clear signal is received from a second node upstream of the first node on the first path. The first client signal failure clear signal indicates that a non-restorable fault has been resolved such that the first path can be considered for carrying data traffic. The non-restorable fault is a failure at the source. Subsequent to receiving the first signal indicating the failure within the first path, a backward defect indication clear signal is transmitted to the second node, the backward defect indication clear signal indicating an absence of a failure in the first path.

Coming of Age of AI-Assisted Network Management & Control

Abstract: The utilization of AI/ML techniques in transport networks is a current area of focus of the research community and industry alike. Leveraging the availability of data to improve how networks are operated holds the promise of simplified network operation and enhanced network optimization. However, materializing the promise of AI/ML will demand a joint effort and close cooperation between system vendors and network operators as it can only be achieved through a shift in long standing operational paradigms. That change is already well under way in the transition from Central Office centric networks towards Datacenter networking. This paper discusses the adoption of AI/ML in production networks as part of this ongoing transformation.

Maximizing Throughput Via Vertical Optimization of the Coherent MODEM

Abstract: Vertical optimization of DSP algorithms, analog electronics, optical components and PCB design is critical to maximize the SNR limit of the digital coherent MODEM. We demonstrate a record net ISD of 10.82b/s/Hz for a vertically optimized 256QAM transceiver operating at a symbol rate >50GBd.

Method and apparatus for rapid recovery of optical power after transient events in C+L band optical networks

Abstract: An optical device having an amplifier and a controller is described. The amplifier is configured to amplify an optical signal in at least one of the C-Band or the L-Band. The controller includes a processor and a non-transitory computer readable medium. The non-transitory computer readable medium storing computer executable code that when executed by the processor causes the processor to: select a target tilt and gain setting from a plurality of target tilt and gain settings stored in the non-transitory computer readable medium based on the type of fault event message responsive to a fault event message affecting the C-band or the L-Band. The selected and pre-calculated target tilt and gain settings are applied to the amplifier.

Nonlinearity mitigation dependence on modulation format in phase-sensitively amplified fiber links

Abstract: We show that the transmission reach increase with phase-sensitive amplifiers (PSAs) compared to phase-insensitive amplifiers is significantly enhanced for higher-order modulation formats in single-channel, single-span transmission experiments.

Input-distribution-aware successive cancellation list decoding of polar codes

Abstract: Polar codes are linear block codes that can achieve channel capacity at infinite code length. Successive cancellation list (SCL) decoding relies on a set of parallel decoders; it yields good error-correction performance at finite code length, at the cost of increased implementation complexity and power consumption. Current efforts in literature focus on design-time decoder complexity reduction, while lacking practical run-time power reduction methods. In this work, input-distribution-aware SCL (IDA-SCL) decoding is proposed, that allows to determine the parallelism to adopt by performing simple observations on the input of the decoder. This technique guarantees fixed, short latency and allows hardware SCL decoders to dynamically shut down part of the internal parallelism before each decoding process. It can be combined with existing complexity- and power- reduction techniques. Simulation results show that IDA-SCL can reduce the run-time complexity of SCL of up to 50\%.

Digital nonlinear phase compensator for legacy submarine cables

Abstract: A method and system are herein disclosed. A coherent optical receiver receives a first optical data carrier signal at a first instant of time and a second optical data carrier signal at a second instant of time, generates at least four first data streams from the first optical data carrier signal and at least four second data streams from the second optical data carrier signal; and circuitry calculates a first aggregate power of the first data streams and a second aggregate power of the second data streams; applies an adjustable temporal low pass filter to the first aggregate power and the second aggregate power resulting in a compensation power, the adjustable temporal low pass filter adjusted to achieve a performance metric; and phase-rotates the first data streams and the second data streams proportional to the compensation power.

Synchronization of a mm-Wave Frequency Comb to a Chip-Scale Mode-Locked Laser via Harmonic Injection Locking

Abstract: A mm-Wave frequency comb with 240GHz spacing is synchronized to a MLL-PIC using harmonic injection locking, this represent optical frequency division of 24x. The Allan Deviation on the repetition rate stability is 10−10 at 1s.

Apparatus and method to reduce the impact of coherent crosstalk in optical networks

Abstract: Optical networks, nodes and methods are disclosed. To solve the aggressor issue and to reduce the cross-talk caused by the aggressors in colorless, directionless and contentionless reconfigurable optical add drop multiplexer nodes, the present disclosure configures a first broadcast module to supply only non-adjacent wavelengths to a first input port of a wavelength selective switch, and a second broadcast module to supply only non-adjacent wavelengths to a second input port of the wavelength selective switch.

InP-based Transceivers for Generation and Transmission of 800 Gbit/s Signals

Abstract: We present our recent progress in coherent transmitters (Tx) and receivers (Rx) based on Photonic Integrated Circuits (PIC) on the InP platform. We demonstrate signal generation and transmission at 800 Gbit/s per optical channel.

Systems and methods for decoupled optical network link traversal

Abstract: Methods and systems are disclosed for optical network link traversal, including a method comprising the steps of receiving, by a traverser software module for an optical network, from a first node in a network link defining a path in the optical network, one or more node sets indicative of one or more of a second node also in the network link; determining, with the traverser software module, an order of traversal of the one or more node sets; traversing the network link using the determined order of traversal; communicating, by the traverser software module, information with a feature manager software module for a first software feature, the first software feature configured to perform a function specific to a specific node; and triggering, by the feature manager software module, the first software feature to execute one or more computer executable instruction based on information from the traverser software module.

Challenges in Coding, DSP and Parallel Operation of Quantum Key Distribution and Coherent Data Transmission

Abstract: We discuss challenges and recent progress on coding, digital signal processing and joint transmission with classical data channels, for quantum key distribution.

Optical synchronization between a 300 GHz frequency comb and a 10 GHz chip-scale MLL

Abstract: A mmWave optical frequency comb with a repetition rate of ~300GHz is synchronized to a MLL with a repetition rate of ~10GHz via harmonic injection locking using <70µW of locking power. The master laser is locked to a 30k Finesse etalon via PDH frequency stabilization.

Method and system to prevent false restoration and protection in optical networks with a sliceable light source

Abstract: A transport network, a node, and a method are disclosed. The transport network, the node, and the method detect a failure of a super channel originating from a sliceable light source that is routed through the transport network, by detecting an optical loss of signal by an optical power monitoring device, in presence or absence of an optical loss of signal of the complete band by at least one photo detector. This information is analyzed with a fault detection algorithm using a patch cable network configuration to determine a fault indication for a failure within the first node. The fault signal indicative of the fault indication is then passed to another node on the first path.