Showing papers on "Wavelength-division multiplexing published in 2019"

15.73 Gb/s Visible Light Communication With Off-the-Shelf LEDs

Abstract: Visible light communication (VLC) can provide high-speed data transmission that could alleviate the pressure on the conventional radio frequency spectrum with the looming capacity crunch for digital communication systems In this paper, we present experimental results of a VLC system with a data rate of 1573 Gb/s after applying forward error correction coding over a 16 m link Wavelength division multiplexing is utilized to efficiently modulate four wavelengths in the visible light spectrum Four single color low-cost commercially available light emitting diodes (LEDs) are chosen as light sources This confirms the feasibility and readiness of VLC for high-data rate communication Orthogonal frequency division multiplexing (OFDM) with adaptive bit loading is used The system with the available components is characterized and its parameters, such as LED driving points and OFDM signal peak-to-peak scaling factor, are optimized To the best of our knowledge, this is the highest data rate ever reported for LED-based VLC systems

Wavelength division multiplexing of continuous variable quantum key distribution and 18.3 Tbit/s data channels

Abstract: Quantum key distribution (QKD) can offer communication with unconditional security and is a promising technology to protect next generation communication systems. For QKD to see commercial success, several key challenges have to be solved, such as integrating QKD signals into existing fiber optical networks. In this paper, we present experimental verification of QKD co-propagating with a large number of wavelength division multiplexing (WDM) coherent data channels. We show successful secret key generation over 24 h for a continuous-variable QKD channel jointly transmitted with 100 WDM channels of erbium doped fiber amplified polarization multiplexed 16-ary quadrature amplitude modulation signals amounting to a datarate of 18.3 Tbit/s. Compared to previous co-propagation results in the C-band, we demonstrate more than a factor of 10 increase in the number of WDM channels and more than 90 times higher classical bitrate, showing the co-propagation with Tbit/s data-carrying channels. The security of communications networks is a fundamental challenge of the current era, particularly with the move towards quantum communications. The authors perform joint transmission of quantum key distribution and up to 100 classical communication channels in the same fiber and report an average secret key rate of 27.2 kbit/s over a 24 h operation period where the classical data rate amounted to 18.3 Tbit/s.

Turn-key, high-efficiency Kerr comb source

Abstract: We demonstrate an approach for automated Kerr comb generation in the normal group-velocity dispersion (GVD) regime. Using a coupled-ring geometry in silicon nitride, we precisely control the wavelength location and splitting strength of avoided mode crossings to generate low-noise frequency combs with pump-to-comb conversion efficiencies of up to 41%, which is the highest reported to date for normal-GVD Kerr combs. Our technique enables on-demand generation of a high-power comb source for applications such as wavelength-division multiplexing in optical communications.

Ultra-Wideband WDM Transmission in S-, C-, and L-Bands Using Signal Power Optimization Scheme

Abstract: Ultra-wideband (UWB) wavelength division multiplexed (WDM) transmission using high-order modulation formats is one of the key techniques to expand the transmission capacity per optical fiber. For UWB systems, the nonlinear interaction caused by inter-band stimulated Raman scattering (SRS) must be considered. Therefore, we have proposed and demonstrated a scheme to optimize the fiber input powers for UWB transmission systems considering the signal power transition caused by the inter-band SRS. We demonstrated a single-mode capacity of 150.3 Tb/s using the proposed power optimization scheme with 13.6-THz UWB in the S-, C-, and L-bands over 40-km transmission. Spectral efficiency of 11.05 b/s/Hz was achieved with 272-channel 50-GHz spaced WDM signals of 45-GBaud polarization division multiplexed 128 quadrature amplitude modulation.

Laser Frequency Combs for Coherent Optical Communications

Abstract: Laser frequency combs with repetition rates on the order of 10 GHz and higher can be used as multi-carrier sources in wavelength-division multiplexing (WDM). They allow replacing tens of tunable continuous-wave lasers by a single laser source. In addition, the comb's line spacing stability and broadband phase coherence enable signal processing beyond what is possible with an array of independent lasers. Modern WDM systems operate with advanced modulation formats and coherent receivers. This introduces stringent requirements in terms of signal-to-noise ratio, power per line, and optical linewidth which can be challenging to attain for frequency comb sources. Here, we set quantitative benchmarks for these characteristics and discuss tradeoffs in terms of transmission reach and achievable data rates. We also highlight recent achievements for comb-based superchannels, including >10 Tb/s transmission with extremely high spectral efficiency, and the possibility to significantly simplify the coherent receiver by realizing joint digital signal processing. We finally discuss advances with microresonator frequency combs and compare their performance in terms of flatness and conversion efficiency against state-of-the-art electro-optic frequency comb generators. This contribution provides guidelines for developing frequency comb sources in coherent fiber-optic communication systems.

High-speed uni-traveling carrier photodiode for 2 μm wavelength application

Abstract: Current optical communication systems operating at the 1.55 μm wavelength band may not be able to continually satisfy the growing demand on data capacity within the next few years. Opening a new spectral window around the 2 μm wavelength with recently developed hollow-core photonic bandgap fiber and a thulium-doped fiber amplifier is a promising solution to increase transmission capacity due to the low-loss and wide-bandwidth properties of these components at this wavelength band. However, as a key component, the performance of current high-speed photodetectors at the 2 μm wavelength is still not comparable with those at the 1.55 μm wavelength band, which chokes the feasibility of the new spectral window. In this work, we demonstrate, for the first time to our knowledge, a high-speed uni-traveling carrier photodiode for 2 μm applications with InGaAs/GaAsSb type-II multiple quantum wells as the absorption region, which is lattice-matched to InP. The devices have the responsivity of 0.07 A/W at 2 μm wavelength, and the device with a 10 μm diameter shows a 3 dB bandwidth of 25 GHz at −3 V bias voltage. To the best of our knowledge, this device is the fastest photodiode among all group III-V and group IV photodetectors working in the 2 μm wavelength range.

High Capacity Transmission With Few-Mode Fibers

Abstract: We experimentally investigate high-capacity few-mode fiber transmission for short and medium-haul optical links. In separate experiments, we demonstrate C + L band transmission of 283 Tbit/s over a single 30 km span and recirculating loop transmission of 159 Tbit/s over 1045 km graded-index three mode fiber. The first experiment reached a data-rate per fiber mode within 90% of the record data-rates reported in the same transmission bands for single-mode fibers. The second experiment demonstrated the feasibility of reaching high data-rates over long distance few-mode fiber transmission, despite strong impairments due to mode-dependent loss and differential mode delay.

20 Gb/s Hybrid CWDM/DWDM for Extended Reach Fiber to the Home Network Applications

Abstract: Five channels hybrid DWDM/CWDM fiber to the home optical network with bit rate of 20 Gb/s has been demonstrated in this paper. The role of DWDM to increase the network capacity with the same service quality has been illustrated. Upgrading the already running network to cover the extra number of subscribers and the different destinations that asked for the fiber links is discussed. The role of the dispersion compensating fiber (DCF) in enhancing the network has been demonstrated. The comparison between the different methods of the dispersion compensation using DCF is illustrated. The effect of the DWDM on the network and optimizing the transmission power to achieve the required distances are discussed.

Phase-coherent lightwave communications with frequency combs.

Abstract: Fiber-optical networks are a crucial telecommunication infrastructure in society. Wavelength division multiplexing allows for transmitting parallel data streams over the fiber bandwidth, and coherent detection enables the use of sophisticated modulation formats and electronic compensation of signal impairments. In the future, optical frequency combs may replace multiple lasers used for the different wavelength channels. We demonstrate two novel signal processing schemes that take advantage of the broadband phase coherence of optical frequency combs. This approach allows for a more efficient estimation and compensation of optical phase noise in coherent communication systems, which can significantly simplify the signal processing or increase the transmission performance. With further advances in space division multiplexing and chip-scale frequency comb sources, these findings pave the way for compact energy-efficient optical transceivers.

Spatial channel network (SCN): Opportunities and challenges of introducing spatial bypass toward the massive SDM era [invited]

Abstract: Considering middle-term predictions of the need for commercial 10-Tb/s optical interfaces working in 1-P b/s optical transport systems by 2024 and recalling the introduction of the optical bypass when entering the wavelength-abundant era in the early 2000s, we re-evaluate the values of hierarchical optical network architecture in light of the forthcoming massive spatial division multiplexing (SDM) era. We introduce a spatial channel (SCh) network (SCN) architecture, where the SDM layer is explicitly defined as a new networking layer that supports the new multiplexing technology of SDM. In an SCN, optical channels (OChs) accommodated in an express SCh bypass the overlying wavelength cross-connects (WXCs) using spatial cross-connects (SXCs) on the route. As one challenge that SCNs will present, we point out that an excessively large SXC insertion loss reduces the optical reach for spectrally groomed OChs. We show that the optical reach of spectrally groomed OChs can be maintained at almost the same level as that for an OCh transported through a conventional single-layer WDM network thanks to the low-loss features of commercially available spatial switches and foreseeable low-loss SDM multiplexers and demultiplexers. As another challenge, we discuss how to achieve growable, reliable, and cost-effective SXCs. We propose two SXC architectures based on sub-matrix switches and core-selective switches. Simple cost assessment shows that the proposed architectures are more cost-effective than the full-size matrix switch-based architecture with 1 + 1 equipment protection and conventional stacked WXC architecture.

Multi-fiber distributed thermal profiling of minimally invasive thermal ablation with scattering-level multiplexing in MgO-doped fibers.

Abstract: We propose a setup for multiplexed distributed optical fiber sensors capable of resolving temperature distribution in thermo-therapies, with a spatial resolution of 2.5 mm over multiple fibers interrogated simultaneously. The setup is based on optical backscatter reflectometry (OBR) applied to optical fibers having backscattered power significantly larger than standard fibers (36.5 dB), obtained through MgO doping. The setup is based on a scattering-level multiplexing, which allows interrogating all the sensing fibers simultaneously, thanks to the fact that the backscattered power can be unambiguously associated to each fiber. The setup has been validated for the planar measurement of temperature profiles in ex vivo radiofrequency ablation, obtaining the measurement of temperature over a surface of 96 total points (4 fibers, 8 sensing points per cm2). The spatial resolution obtained for the planar measurement allows extending distributed sensing to surface, or even three-dimensional, geometries performing temperature sensing in the tissue with millimeter resolution in multiple dimensions.

Design and Performance Analysis of the WDM Schemes for Radio over Fiber System With Different Fiber Propagation Losses

Abstract: The integration of optical and wireless networks increases mobility and capacity and decreases costs in access networks. Fibre optic communication can be considered optical communication that combines the methodologies of two communications, and it may be utilised in systems of wired and wireless communication. The solution for many problems is radio over fibre (RoF) because it can control many base stations (BS) that are connected to a central station (CS) with an optical fibre. The received RoF signal head for in a low quality; thus, many factors will result in some problems such as a high bit error rate (BER) and low Q-factor values, and the receiver might not be operating in a high data rate network. Wavelength division multiplexing (WDM) network can offer a solution to these problems where the transmission of different signals can be done with a single-mode fibre. BER should be reduced to assured values, and the Q-factor must be increased. The investigation of WDM-RoF with different lengths of fibre at various channel spacing will be simulated using Optisystem software, and the RoF’s receiver performance is measured and analyzed depending on the acquired BER, the value of the Q-factor, and the height of the opening of the eye diagram. The degradation factors effect such as attenuation and dispersion are significantly limited with the addition of an EDFA amplifier to a Single Mode Fibre (SMF).

Dual-Polarization Non-Linear Frequency-Division Multiplexed Transmission With $b$ -Modulation

Abstract: There has been much interest in the non-linear frequency-division multiplexing (NFDM) transmission scheme in the optical fiber communication system. Up to date, most of the demonstrated NFDM schemes have employed only single polarization for data transmission. Employing both polarizations can potentially double the data rate of NFDM systems. We investigate in simulation a dual-polarization NFDM transmission with data modulation on the $b$ -coefficient. First, a transformation that facilitates the dual-polarization $b$ -modulation was built upon an existing transformation in [M. Yousefi and X. Yangzhang, “Linear and nonlinear frequency-division multiplexing,” in Proc. Eur. Conf. Opt. Commun. , Dusseldorf, Germany, Sep. 2016, pp. 342-344]. Second, the $q_c$ - and $b$ -modulation for dual polarization were compared in terms of Q -factor, spectral efficiency (SE), and correlation of sub-carriers. The correlation is quantified via information theoretic metrics, joint and individual entropy. The polarization-multiplexed $b$ -modulation system shows 1-dB Q -factor improvement over $q_c$ -modulation system due to a weaker correlation of sub-carriers and less effective noise. Finally, the $b$ -modulation system was optimized for high data rate, achieving a record net data rate of 400 Gb/s (SE of 7.2 b/s/Hz) over $12\times 80$ km of standard single-mode fiber with erbium-doped fiber amplifiers. Based on the aforementioned simulation results, we further point out the drawbacks of our current system and quantify the error introduced by the transceiver algorithms and non-integrability of the channel

Discrete multitone transmission for underwater optical wireless communication system using probabilistic constellation shaping to approach channel capacity limit.

Abstract: Probabilistic constellation shaping (PCS) is utilized to approach the channel capacity limit in discrete multitone (DMT) transmission for underwater optical wireless communication (UOWC) system. A fixed quadrature amplitude modulation (QAM) format with various probabilistic distributions is individually allocated for different subcarriers to obtain achievable maximum channel capacity in accordance with the pre-estimated signal-to-noise ratio. By using a 450-nm directly modulated laser diode (LD) with an available modulation bandwidth of ∼2.75 GHz, DMT with PCS technique is experimentally realized with a net data rate of 18.09 Gbit/s over 5 m, 17.21 Gbit/s over 25 m, and 12.62 Gbit/s over 35 m underwater transmission, giving substantial capacity improvement of 32.22%, 30.03%, and 27.55%, respectively, in comparison with the widely used regular QAM formats in DMT with bit-power loading scheme. The figure of merit of the UOWC system in terms of entropy, generalized mutual information (GMI), and normalized GMI are also presented. To the best of our knowledge, this is the first time to employ PCS-QAM-DMT in a UOWC system, and it is also the highest data rate ever reported for a single LD in UOWC.

An Optical Five Channel Demultiplexer-Based Simple Photonic Crystal Ring Resonator for WDM Applications

Abstract: Abstract We have proposed simple ring resonator 5-channel demultiplexer based on optical channel drop filter analysis that is applicable at third communication window (1550 nm) range. Our proposed base filter is the important part in designing the demultiplexer, inclusive one ring resonator contains one square dielectric rod at core. Demultiplexer structure introduced by arranging five filter with different ring core refractive index. Insomuch every ring core have individual refractive index, thus each ring have diverse resonant wavelength. Numerical results by the finite difference time domain (FDTD) method show quality factor (Q) and transmission efficiency of fundamental channel drop filter are 1038 and 93 %, respectively. It is found that transmission efficiency in designed demultiplexer is more than 90 % for each channel; channel spacing is less than 4.2 nm. The average crosstalk value, total footprint of demutiplexer is −17.85 dB, 689.61 μm2, respectively. Small size with a very simple ring design can be benefit in photonic integrated circuit.

Enabling Technologies for Fiber Nonlinearity Mitigation in High Capacity Transmission Systems

Abstract: Fiber nonlinearity has become a major limiting transmission impairment factor. In this paper, we discuss various nonlinearity mitigation techniques in electrical and optical domains. In electrical domain, multiple reduced complexity digital back-propagation algorithms were developed, including perturbation back-propagation. One drawback is that they can compensate for intra-channel self-phase modulation (SPM) effects only. The inter-channel fiber nonlinearity mitigation can be done in optical domain. For example, digital subcarrier multiplexing (SCM) can effectively mitigate both SPM and cross-phase modulation (XPM) effects. It can become even more beneficial for higher symbol rate systems (e.g., 64 Gbaud and 128 Gbaud) and has a capability to deliver longer reach than single carrier 32 Gbaud DP-16QAM signals and only slightly shorter reach (by up to 7%) compared to 32 Gbaud SCM systems. Another technique, the total intensity directed phase modulation, can provide per-span SPM and XPM compensation. However, this technique is limited to compensation of a few channels only. On the other hand, the proposed enhanced pre-dispersed spectral inversion can effectively compensate for SPM/XPM effects of multiple channels and become more practical by removing limitation to link symmetry even in nonuniform transmission links. Finally, subcarrier power pre-emphasis in optical superchannels can equalize performance of all subcarriers by mitigating intersubcarrier XPM and extend transmission reach by 20%.

35-Tb/s C-Band Transmission Over 800 km Employing 1-Tb/s PS-64QAM Signals Enhanced by Complex 8 × 2 MIMO Equalizer

Abstract: We demonstrate the full C-band 1-Tb/s/λ WDM 800-km transmission with 35-Tb/s capacity employing novel complex 8 × 2 MIMO equalizer which enables simultaneous compensation of imperfections of transmitter and receiver of 120-Gbaud probabilistically-shaped-64QAM signals.

Low-Resolution Digital Pre-Compensation Enabled by Digital Resolution Enhancer

Abstract: Digital pre-compensation (DPC) is an indispensable block of state-of-the-art optical transceivers, and a key enabler for high-order modulation formats (HOMFs) transmission. A crucial component, which enables the transmission of the precompensated HOMFs, is the digital-to-analog-converter (DAC). However, as data and symbol rates grow, the implementation of such devices becomes highly challenging in terms of performance, power consumption, and costs. In this paper, a digital-resolution-enhancer (DRE) algorithm is discussed, conjoined with high-end DPC methods. Simulation results demonstrate that the DRE reduces the effect of DAC quantization noise power by more than 8 dB for the considered cases of 400G with 64QAM. The proposed scheme is experimentally verified by transmitting a 4-bit DP-64QAM 400 Gbit/s signal in a WDM scenario over 95 km of single mode fiber.

Importance of Amplifier Physics in Maximizing the Capacity of Submarine Links

Abstract: The throughput of submarine transport cables is approaching fundamental limits imposed by amplifier noise and Kerr nonlinearity. Energy constraints in ultra-long submarine links exacerbate this problem, as the throughput per fiber is further limited by the electrical power available to the undersea optical amplifiers. Recent works have studied how employing more spatial dimensions can mitigate these limitations. In this paper, we address the fundamental question of how to optimally use each spatial dimension. Specifically, we discuss how to optimize the channel power allocation in order to maximize the information-theoretic capacity under an electrical power constraint. Our formulation accounts for amplifier physics, Kerr nonlinearity, and power feed constraints. Whereas recent works assume that the optical amplifiers operate in deep saturation, where power conversion efficiency (PCE) is high, we show that given a power constraint, operating in a less saturated regime, where PCE is lower, supports a wider bandwidth and a larger number of spatial dimensions, thereby maximizing capacity. This design strategy increases the capacity of submarine links by about 70% compared to the theoretical capacity of a recently proposed high-capacity system.

High-speed optical secure communication with external noise source and internal time-delayed feedback loop

Abstract: We propose and experimentally demonstrate a novel physical layer encryption scheme for high-speed optical communication. A 10 Gb/s on-off keying signal is secretly transmitted over 100 km standard single-mode fiber. The intensity-modulated message is secured by the encryption mechanism, which is composed of an external noise source and an internal time-delayed feedback loop. The external noise serves as an entropy source with sufficient randomness. The feedback loop structure in the transmitter introduces a time-domain encryption key space, and a corresponding open-loop configuration at the receiver side is used for synchronization and decryption. Experiment results show the effectiveness of the proposed scheme. For a legitimate terminal, bit error rate below 10−8 can be obtained. Decryption degradations with the mismatch of different hardware parameters are researched. The time delay in the feedback loop provides a sensitive encryption key. For other hardware parameters, the system is robust enough for synchronization. Meanwhile, the time-delay signature of the loop is able to be well concealed by the external noise. Moreover, the proposed scheme can support density wavelength division multiplexing transmission with a relatively simple structure. This work also provides a new concept to establish optical secure communication by combining a time-delayed feedback chaotic system and random noise.

Nonlinearity-Free Coherent Transmission in Hollow-Core Antiresonant Fiber

Abstract: We demonstrate the first multiterabit/s wavelength division multiplexing data transmission through hollow-core antiresonant fiber (HC-ARF). In total, 16 channels of 32-GBd dual-polarization Nyquist-shaped 256QAM signal channels were transmitted through a 270-m-long fiber without observing any power penalty. In a single-channel high power transmission experiment, no nonlinearity penalty was observed for up to 1 W of received power, despite the very low chromatic dispersion of the fiber (<2 ps/nm/km). Our simulations show that such a low level of nonlinearity should enable transmission at 6.4 Tb/s over 1200 km of HC-ARF, even when the fiber attenuation is significantly greater than that of SMF-28. As signals propagate through hollow-core fibers at close to the speed of light in vacuum such a link would be of interest in latency-sensitive data transmission applications.

Scaling Capacity Growth of Fiber-Optic Transmission Systems Using 100+nm Ultra-Wideband Semiconductor Optical Amplifiers

Abstract: We report on the use of semiconductor optical amplifiers (SOAs) to extend the optical bandwidth of next generation optical systems. After discussing the technological progress and the motivation for rekindling the interest in SOAs for line amplification, we point out that the nonlinear gain dynamics of SOA is not a limiting factor for employing SOA as line amplifier. We show that the passage to high wavelength division multiplexed (WDM) channel count tends to substantially reduce nonlinear impairments, both through numerical analysis and experimental investigations based on standard off the shelf SOA devices. We then present the characteristics of our novel ultrawideband SOA-based packaged devices exhibiting high gain over 100+nm optical bandwidth, high output saturation power and low noise figure. We finally review the recent demonstration of the first >100+Tb/s transmission based on such novel 100+ nm wide semiconductor optical amplifiers over 100 km distance.

Power handling of silicon microring modulators

Abstract: Silicon photonic wavelength division multiplexing (WDM) transceivers promise to achieve multi-Tbps data rates for next-generation short-reach optical interconnects. In these systems, microring resonators are important because of their low power consumption and small footprint, two critical factors for large-scale WDM systems. However, their resonant nature and silicon's strong optical nonlinearity give rise to nonlinear effects that can deteriorate the system's performance with optical powers on the order of milliwatts, which can be reached on the transmitter side where a laser is directly coupled into resonant modulators. Here, a theoretical time-domain nonlinear model for the dynamics of optical power in silicon resonant modulators is derived, accounting for two-photon absorption, free-carrier absorption and thermal and dispersion effects. This model is used to study the effects of high input optical powers over modulation quality, and experimental data in good agreement with the model is presented. Two major consequences are identified: the importance of a correct initialization of the resonance wavelength with respect to the laser due to the system's bistability; and the existence of an optimal input optical power beyond which the modulation quality degrades.

WDM-compatible multimode optical switching system-on-chip

Abstract: The development of optical interconnect techniques greatly expands the communication bandwidth and decreases the power consumption at the same time. It provides a prospective solution for both intra-chip and inter-chip links. Herein reported is an integrated wavelength-division multiplexing (WDM)-compatible multimode optical switching system-on-chip (SoC) for large-capacity optical switching among processors. The interfaces for the input and output of the processor signals are electrical, and the on-chip data transmission and switching process are optical. It includes silicon-based microring optical modulator arrays, mode multiplexers/ de-multiplexers, optical switches, microring wavelength de-multiplexers and germanium-silicon high-speed photodetectors. By introducing external multi-wavelength laser sources, the SoC achieved the function of on-chip WDM and mode-division multiplexing (MDM) hybrid-signal data transmission and switching on a standard silicon photonics platform. As a proof of concept, signals with a 25 Gbps data rate are implemented on each microring modulator of the fabricated SoC. We illustrated 25 x 3 x 2 Gbps on-chip data throughput with two-by-two multimode switching functionality through implementing three wavelength-channels and two mode-channel hybrid-multiplexed signals for each multimode transmission waveguide. The architecture of the SoC is flexible to scale, both for the number of supported processors and the data throughput. The demonstration paves the way to a large-capacity multimode optical switching SoC.

High Capacity Mode Division Multiplexing Based MIMO Enabled All-Optical Analog Millimeter-Wave Over Fiber Fronthaul Architecture for 5G and Beyond

Abstract: The ever-increasing proliferation of mobile users and new technologies, and the demands for ubiquitous connectivity, high data capacity, faster data speed, low latency, and reliable services have been driven the quest for the next generation, fifth generation (5G), of the wireless networks. Cloud radio access network (C-RAN) has been identified as a promising architecture for addressing 5G requirements. However, C-RAN enforces stringent requirements on the fronthaul capacity and latency. To this end, several fronthaul solutions have been proposed in the literature, ranging from transporting digitized radio signals over fiber and functional splits to an entirely analog-radio-over fiber (A-RoF) based fronthual. A-RoF is a highly appealing transport solution for fronthual of 5G and beyond owing to its high bandwidth and energy efficiency, low system complexity, small footprint, cost-effectiveness, and low latency. In this paper, a high capacity multiple-input-multiple-output (MIMO) enabled all-optical analog-millimeter-wave-over fiber (A-MMWoF) fronthaul architecture is proposed for 5G and beyond of wireless networks. The proposed architecture employs photonic MMW signals generation and mode division multiplexing (MDM) along with wavelength division multiplexing (WDM) for transporting MMW MIMO signals in the optical domain. In support of the proposed architecture design, a comprehensive state-of-the-art literature review on the recent research works in high capacity A-RoF fronthaul systems and related transport technologies is presented. In addition, the corresponding potential challenges and solutions along with potential future directions are highlighted. The proposed design is flexible and scalable for achieving high capacity, high speed, and low latency fronthaul links.

High-Speed 120 Gbps AMI-WDM-PDM Free Space Optical Transmission System

Abstract: Abstract Free space optical (FSO) communication systems are gaining high popularity from the last decade due to its various advantages such as no license spectrum, low-cost implementation etc. In this work, 160 Gbps data is transmitted over 8 km FSO link by adopting alternate mark inversion (AMI), wavelength division multiplexing (WDM) and polarization division multiplexing (PDM) schemes. The results are reported in terms of Q factor, bit error rate, signal to noise ratio, total received power and eye diagrams.

High-Spectral-Efficiency 600-Gbps/Carrier Transmission Using PDM-256QAM Format

Abstract: High-capacity carrier signals with high-order modulation are being considered for data center interconnection (DCI) applications as they can reduce the cost per bit by decreasing the number of devices and increasing fiber capacity. However, signal quality degradation due to device imperfections affecting the frequency response has limited the capacity per carrier of PDM-256QAM signals to under 400 Gbps. Here, it is possible to use a calibration method for dealing with device imperfections wherein a fixed equalizer separately calibrates the frequency response of the transmitter and receiver. Our previous study showed that PDM-256QAM signals at up to 48 GBaud could be transmitted over 100 km, while it used an experimental setup with total 3-dB analog bandwidth of 13 and 20 GHz for transmitter and receiver, respectively. A micro-integrable tunable laser assembly with a typical linewidth of 20 kHz, maximum under 100 kHz. Actual DCI applications, however, are expected to use dense wavelength division multiplexing (WDM), so in this study, we examined transmission of 10-WDM 48-GBaud PDM-256QAM signals in a 50-GHz grid and evaluated the WDM penalties. The resulting spectral efficiency of 600-Gbps/carrier WDM transmissions was as high as 12.02 bit/s/Hz.

Optical Strategies for Economical Next Generation 50 and 100G PON

Abstract: An overview of optical strategies for economical next-generation 50 and 100G PON is given.