Showing papers on "Wavelength-division multiplexing published in 2017"
TL;DR: The identification of fundamental scaling disparities between the technologies used to generate and process data and those used to transport data could lead to the data transport network falling behind its required capabilities by a factor of approximately 4 every five years, leading to an optical network capacity crunch.
Abstract: Based on a variety of long-term network traffic data from different geographies and applications, in addition to long-term scaling trends of key information and communication technologies, we identify fundamental scaling disparities between the technologies used to generate and process data and those used to transport data. These disparities could lead to the data transport network falling behind its required capabilities by a factor of approximately 4 every five years. By 2024, we predict the need for 10-Tb/s optical interfaces working in 1-Pb/s optical transport systems. To satisfy these needs, multiplexing in both wavelength and space in the form of a wavelength-division multiplexing × space-division multiplexing matrix will be required. We estimate the characteristics of such systems and outline their target specifications, which reveals the need for very significant research progress in multiple areas, from system and network architectures to digital signal processing to integrated arrayed device designs, in order to avoid an optical network capacity crunch.
329 citations
TL;DR: In this paper, a method to multiplex and demultiplex multiple OAMs, wavelengths, and polarizations channels by a highly integrated off-axis technique on a metasurface is presented.
Abstract: Orbital angular momentum (OAM) has recently gained much interest in high-speed optical communication due to its spatial orthogonality. However, complex spatial phase distributions of OAM make the components difficult for nano-photonic integration. In this work, a method to multiplex and demultiplex multiple OAMs, wavelengths, and polarizations channels by a highly integrated off-axis technique on a metasurface is presented. As a multiplexer, beams without OAM can be transferred into coaxial beams carrying different OAM features by different incident angles; as a demultiplexer, coaxial beams carrying multi-OAMs can be divided into different directions with fundamental modes. Furthermore, the component based on dipole optical antenna metasurface can be used not only as an OAM multiplexer/demultiplexer but also as a multiplexer/demultiplexer to achieve wavelength division multiplexing and polarization-division multiplexing, as both these applications are based on the conservations of momentum and angular momentum. For practical applications, phase-only hologram is analyzed to demonstrate multiple functions of this method.
147 citations
TL;DR: This paper focuses on the routing, spectrum, and core and/or mode assignment (RSCMA) problem for future SDMEONs, and proposes SCMA methods with efficiency and flexibility awareness, exploiting prioritized area concept and crosstalk awareness depending on whether MCF or MMF supports intercore/intermode crosStalk.
Abstract: Elastic optical networks (EONs) are considered to be one of the promising future networks for spectrum flexibility. In conventional wavelength-division multiplexing networks, routing and wavelength assignment is one of the key issues, whereas the routing and spectrum assignment (RSA) problem considerably affects the network performance in EONs. In addition, the data-center traffic and mobile back-haul traffic keeps increasing. To deal with such increasing capacity of applications, space-division multiplexing (SDM) technologies such as multi-core fiber (MCF) and multi-mode fiber (MMF) have been intensively researched. From the network perspective, this paper focuses on the routing, spectrum, and core and/or mode assignment (RSCMA) problem for future SDM-EONs. Introducing MCF or MMF further complicates the RSA problem because the fiber core or mode dimension is newly expanded. In addition, physical impairment caused by MCF or MMF must be considered. In this paper, the target RSCMA problem is first divided into routing and SCMA problems, and a pre-computation method based on the K-shortest path is introduced as the routing solution. Next, we propose SCMA methods with efficiency and flexibility awareness, exploiting prioritized area concept and crosstalk awareness depending on whether MCF or MMF supports intercore/intermode crosstalk. Finally, the paper evaluates and compares the effectiveness of the proposed algorithms with that of representative algorithms.
138 citations
TL;DR: This paper reviews digital signal processing techniques that compensate, mitigate, and exploit fiber nonlinearities in coherent optical fiber transmission systems.
Abstract: This paper reviews digital signal processing techniques that compensate, mitigate, and exploit fiber nonlinearities in coherent optical fiber transmission systems.
99 citations
TL;DR: A review is given on recent progresses in silicon nanophotonic integrated devices for multiplexing and switching, which are key elements in a multichannel multiplexed photonic networks-on-chip.
Abstract: A review is given on our recent progresses in silicon nanophotonic integrated devices for multiplexing and switching, which are key elements in a multichannel multiplexed photonic networks-on-chip. On-chip (de)multiplexers include wavelength-division-multiplexing filters based on arrayed-waveguide gratings and microring resonators, polarization-division-multiplexing devices like polarizers, polarization-beam splitters and polarization rotators, mode-division-multiplexing devices, and some novel hybrid (de)multiplexers enabling more than one multiplexing technologies simultaneously. Thermal-switchable silicon photonic devices are also discussed regarding the increasing demands for reconfigurable photonic networks-on-chip, including high-performance optical switches and reconfigurable add-drop multiplexers.
96 citations
TL;DR: A survey on fiber nonlinearity compensation (NLC) techniques is provided and focuses on the well-known NLC techniques and discusses their performance, as well as their implementation and complexity.
Abstract: Optical communication systems represent the backbone of modern communication networks. Since their deployment, different fiber technologies have been used to deal with optical fiber impairments such as dispersion-shifted fibers and dispersion-compensation fibers. In recent years, thanks to the introduction of coherent detection based systems, fiber impairments can be mitigated using digital signal processing (DSP) algorithms. Coherent systems are used in the current 100 Gb/s wavelength-division multiplexing (WDM) standard technology. They allow the increase of spectral efficiency by using multilevel modulation formats, and are combined with DSP techniques to combat linear fiber distortions. In addition to linear impairments, the next generation 400 Gb/s and 1 Tb/s WDM systems are also more affected by the fiber nonlinearity due to the Kerr effect. At high input powers, fiber nonlinear effects become more important and their compensation is required to improve the transmission performance. Several approaches have been proposed to deal with the fiber nonlinearity. In this paper, after a brief description of the Kerr-induced nonlinear effects, a survey on fiber nonlinearity compensation (NLC) techniques is provided. We focus on the well-known NLC techniques and discuss their performance, as well as their implementation and complexity. An extension of the inter-subcarrier nonlinear interference canceler approach is also proposed. A performance evaluation of the well-known NLC techniques and the proposed approach is provided in the context of Nyquist and super-Nyquist superchannel systems.
84 citations
TL;DR: In this article, the impact of probabilistic shaping on effective signal-to-noise ratios (SNRs) and achievable information rates (AIRs) in a back-toback configuration and in unrepeated nonlinear fiber transmissions was investigated.
Abstract: This paper studies the impact of probabilistic shaping on effective signal-to-noise ratios (SNRs) and achievable information rates (AIRs) in a back-to-back configuration and in unrepeated nonlinear fiber transmissions. For the back-to-back setup, various shaped quadrature amplitude modulation (QAM) distributions are found to have the same implementation penalty as uniform input. By demonstrating in transmission experiments that shaped QAM input leads to lower effective SNR than uniform input at a fixed average launch power, we experimentally confirm that shaping enhances the fiber nonlinearities. However, shaping is ultimately found to increase the AIR, which is the most relevant figure of merit, as it is directly related to spectral efficiency. In a detailed study of these shaping gains for the nonlinear fiber channel, four strategies for optimizing QAM input distributions are evaluated and experimentally compared in wavelength division multiplexing (WDM) systems. The first shaping scheme generates a Maxwell–Boltzmann (MB) distribution based on a linear additive white Gaussian noise channel. The second strategy uses the Blahut–Arimoto algorithm to optimize an unconstrained QAM distribution for a split-step Fourier method based channel model. In the third and fourth approach, MB-shaped QAM and unconstrained QAM are optimized via the enhanced Gaussian noise (EGN) model. Although the absolute shaping gains are found to be relatively small, the relative improvements by EGN-optimized unconstrained distributions over linear AWGN optimized MB distributions are up to 59%. This general behavior is observed in 9-channel and fully loaded WDM experiments.
77 citations
19 Mar 2017
TL;DR: It is demonstrated that 96-Gbaud LDPC-coded PDM-16QAM channels with FEC redundancy of 12.75% realize high-aggregate spectral efficiency of 217.6 b/s/Hz.
Abstract: We demonstrate the first 1-Pb/s unidirectional inline-amplified transmission over 205.6-km of single-mode 32-core fiber within C-band only. 96-Gbaud LDPC-coded PDM-16QAM channels with FEC redundancy of 12.75% realize high-aggregate spectral efficiency of 217.6 b/s/Hz.
76 citations
TL;DR: For the first time, this work experimentally demonstrate a 9.51-Gb/s WDM UWOC system using a red-emitting laser diode (LD), a single-mode pigtailed green-emmitting LD and a multi- mode pigtailed blue-emitted LD using 32-quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) modulation.
Abstract: The availability of the underwater wireless optical communication (UWOC) based on red (R), green (G) and blue (B) lights makes the realization of the RGB wavelength division multiplexing (WDM) UWOC system possible. By properly mixing RGB lights to form white light, the WDM UWOC system has prominent potentiality for simultaneous underwater illumination and high-speed communication. In this work, for the first time, we experimentally demonstrate a 9.51-Gb/s WDM UWOC system using a red-emitting laser diode (LD), a single-mode pigtailed green-emitting LD and a multi-mode pigtailed blue-emitting LD. By employing 32-quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) modulation in the demonstration, the red-light, the green-light and the blue-light LDs successfully transmit signals with the data rates of 4.17 Gb/s, 4.17 Gb/s and 1.17 Gb/s, respectively, over a 10-m underwater channel. The corresponding bit error rates (BERs) are 2.2 × 10-3, 2.0 × 10-3 and 2.3 × 10-3, respectively, which are below the forward error correction (FEC) threshold of 3.8 × 10-3.
71 citations
TL;DR: In this article, a four-channel wavelength-division-multiplex (WDM) 560 Gbit/s 128 quadrature amplitude modulation (128QAM)-discrete multi-tone (DMT) signal transmission in a short reach interconnect is demonstrated, where coordinated discrete Fourier transform spread and preequalization are jointly used to simultaneously overcome serious frequency domain power attenuation and reduce the peak-to-average power ratio of the DMT signal.
Abstract: In this paper, we experimentally demonstrated a four-channel wavelength-division-multiplex (WDM) 560 Gbit/s 128 quadrature amplitude modulation (128QAM)-Discrete MultiTone (DMT) signal transmission in a short reach interconnect Coordinated discrete Fourier transform-spread and preequalization are jointly used to simultaneously overcome serious frequency domain power attenuation and reduce the peak-to-average power ratio of the DMT signal An additional postdecision-directed least mean square equalizer is used afterward to further compensate the channel response and mitigate the devices’ implementation penalty These proposed algorithms and equalizer are validated through experiment in this paper, we achieved the highest capacity signal transmission in the four-channel WDM transmission system using intensitymodulation and directdetection over a 24-km single mode fiber with a bit-error-ratio under the hard-decision forward error correction limit of 38 × 10-3
69 citations
TL;DR: In this paper, a demultiplexer based on photonic crystals was proposed for dense wavelength division multiplexing transmission systems, where the main cavity was responsible for selecting the wavelength.
TL;DR: In this article, a real-time 8 × 28.125 GBd dense wavelength division multiplexing four-level pulse amplitude modulation (PAM-4) transmission over up to 80 km standard single mode fiber in the C-band is demonstrated.
Abstract: Leveraging client optics based on intensity modulation and direct detection for point-to-point inter-data center interconnect applications is a cost and power efficient solution, but challenging in terms of optical signal-to-noise ratio requirements and chromatic dispersion tolerance. In this paper, real-time 8 × 28.125 GBd dense wavelength division multiplexing four-level pulse amplitude modulation (PAM-4) transmission over up to 80 km standard single mode fiber in the C-Band is demonstrated. Using a combination of optical dispersion compensation and electronic equalization, results below a bit error rate of 1e−6 are achieved and indicate sufficient margin to transmit over even longer distances, if an forward error correction (FEC) threshold of 3.8e-3 is assumed. Moreover, single channel 28.125 GBd PAM-4 is evaluated against optical effects such as optical bandwidth limitations, chromatic dispersion tolerance, and optical amplified spontaneous emission noise.
TL;DR: The Letter reports the inscription of fiber Bragg gratings in a single-crystal sapphire optical fiber via a point-by-point method by 780 nm infrared-femtosecond laser pulses to make wavelength division multiplexing in sappire fiber more practicable.
Abstract: The Letter reports the inscription of fiber Bragg gratings (FBGs) in a single-crystal sapphire optical fiber via a point-by-point method by 780 nm infrared-femtosecond laser pulses. Compared to phase mask exposure, the use of the point-by-point method for the inscription provides a flexible way to fabricate sapphire FBGs and to make wavelength division multiplexing in sapphire fiber more practicable. The multiplexing of three cascade gratings is demonstrated, and their performance up to 1400°C is tested. The permanent enhancement of reflectivity by a factor of about 5 after heat treatment and the nearly linear temperature response with a slope of 25.8 pm/°C are demonstrated.
TL;DR: Although the absolute shaping gains are found to be relatively small, the relative improvements by EGN-optimized unconstrained distributions over linear AWGN optimized MB distributions are up to 59%.
Abstract: This paper studies the impact of probabilistic shaping on effective signal-to-noise ratios (SNRs) and achievable information rates (AIRs) in a back-to-back configuration and in unrepeated nonlinear fiber transmissions. For back-to-back, various shaped quadrature amplitude modulation (QAM) distributions are found to have the same implementation penalty as uniform input. By demonstrating in transmission experiments that shaped QAM input leads to lower effective SNR than uniform input at a fixed average launch power, we experimentally confirm that shaping enhances the fiber nonlinearities. However, shaping is ultimately found to increase the AIR, which is the most relevant figure of merit as it is directly related to spectral efficiency. In a detailed study of these shaping gains for the nonlinear fiber channel, four strategies for optimizing QAM input distributions are evaluated and experimentally compared in wavelength division multiplexing (WDM) systems. The first shaping scheme generates a Maxwell-Boltzmann (MB) distribution based on a linear additive white Gaussian noise channel. The second strategy uses the Blahut-Arimoto algorithm to optimize an unconstrained QAM distribution for a split-step Fourier method based channel model. In the third and fourth approach, MB-shaped QAM and unconstrained QAM are optimized via the enhanced Gaussian noise (EGN) model. Although the absolute shaping gains are found to be relatively small, the relative improvements by EGN-optimized unconstrained distributions over linear AWGN optimized MB distributions are up to 59%. This general behavior is observed in 9-channel and fully loaded WDM experiments.
TL;DR: This work enables large-capacity multimode photonic networks-on-chip and asymmetric directional couplers are employed to construct the mode multiplexers and de-multiplexers, and balanced Mach-Zehnder interferometer is utilized to Construct the 2 × 2 single-mode optical switches.
Abstract: We propose a 2 × 2 multimode optical switch, which is composed of two mode de-multiplexers, n 2 × 2 single-mode optical switches where n is the number of the supported spatial modes, and two mode multiplexers. As a proof of concept, asymmetric directional couplers are employed to construct the mode multiplexers and de-multiplexers, balanced Mach-Zehnder interferometer is utilized to construct the 2 × 2 single-mode optical switches. The fabricated silicon 2 × 2 multimode optical switch has a broad optical bandwidth and can support four spatial modes. The link-crosstalk for all four modes is smaller than −18.8 dB. The inter-mode crosstalk for the same optical link is less than −22.1 dB. 40 Gbps data transmission is performed for all spatial modes and all optical links. The power penalties for the error-free switching (BER<10−9) at 25 Gbps are less than 1.8 dB for all channels at the wavelength of 1550 nm. The power consumption of the device is 117.9 mW in the “cross” state and 116.2 mW in the “bar” state. The switching time is about 21 μs. This work enables large-capacity multimode photonic networks-on-chip.
TL;DR: In this article, a survey on the fiber nonlinearity compensation (NLC) techniques is provided and an extension of the inter-subcarrier nonlinear interference canceler approach is also proposed.
Abstract: Optical communication systems represent the backbone of modern communication networks. Since their deployment, different fiber technologies have been used to deal with optical fiber impairments such as dispersion-shifted fibers and dispersion-compensation fibers. In recent years, thanks to the introduction of coherent detection based systems, fiber impairments can be mitigated using digital signal processing (DSP) algorithms. Coherent systems are used in the current 100 Gbps wavelength-division multiplexing (WDM) standard technology. They allow the increase of spectral efficiency by using multi-level modulation formats, and are combined with DSP techniques to combat the linear fiber distortions. In addition to linear impairments, the next generation 400 Gbps/1 Tbps WDM systems are also more affected by the fiber nonlinearity due to the Kerr effect. At high input power, the fiber nonlinear effects become more important and their compensation is required to improve the transmission performance. Several approaches have been proposed to deal with the fiber nonlinearity. In this paper, after a brief description of the Kerr-induced nonlinear effects, a survey on the fiber nonlinearity compensation (NLC) techniques is provided. We focus on the well-known NLC techniques and discuss their performance, as well as their implementation and complexity. An extension of the inter-subcarrier nonlinear interference canceler approach is also proposed. A performance evaluation of the well-known NLC techniques and the proposed approach is provided in the context of Nyquist and super-Nyquist superchannel systems.
TL;DR: Fiber nonlinearity mitigation is demonstrated by using multiple optical phase conjugations (OPCs) in the WDM transmission systems of both 8 × 32-Gbaud PDM QPSK channels and 8 ×32-Gb aud PDM 16-QAM channels, showing improved performance over a single mid-span OPC and no OPC in terms of nonlinear threshold and a best achievable Q2 factor after transmission.
Abstract: We demonstrate fiber nonlinearity mitigation by using multiple optical phase conjugations (OPCs) in the WDM transmission systems of both 8 × 32-Gbaud PDM QPSK channels and 8 × 32-Gbaud PDM 16-QAM channels, showing improved performance over a single mid-span OPC and no OPC in terms of nonlinear threshold and a best achievable Q2 factor after transmission. In addition, after an even number of OPCs, the signal wavelength can be preserved after transmission. The performance of multiple OPCs for fiber nonlinearity mitigation was evaluated independently for WDM PDM QPSK signals and WDM PDM 16-QAM signals. The technique of multiple OPCs is proved to be transparent to modulation formats and effective for different transmission links. In the WDM PDM QPSK transmission system over 3600 km, by using multiple OPCs the nonlinear threshold (i.e. optimal signal launched power) was increased by ~5 dB compared to the case of no OPC and increased by ~2 dB compared to the case of mid-span OPC. In the WDM PDM 16-QAM transmission system over 912 km, by using the multiple OPCs the nonlinear threshold was increased by ~7 dB compared to the case of no OPC and increased by ~1 dB compared to the case of mid-span OPC. The improvements in the best achievable Q2 factors were more modest, ranging from 0.2 dB to 1.1 dB for the results presented.
TL;DR: It is evident that RDF and hybrid RDF + DFF has presented the highest signal quality factor and optical nonlinearity signal processing in compared with other optical fibers communication channel.
Abstract: Our research presents best candidate different commercial optical fiber communication channel for optical nonlinearity signal processing in high optical transmission bit rate systems in the presence of traveling wave semiconductor optical amplifier (TW-OSA) These optical fibers that are namely dispersion flattened fiber (DFF), reverse dispersion fiber (RDF), non zero dispersion shifted fiber, dispersion compensated fiber, single mode fiber, and hybrid RDF + DFF Wavelength division multiplexing (WDM) system is employed to benefit 80 users with the high transmission bit rates up to 160 Gb/s over optical fiber communication channel length up to 200 km with trying to reduce nonlinearity effects by choosing suitable channel spacing and first or second order Bessel, Gaussian WDM Mux/Demux filter Maximum peak power, optical signal to noise ratio, and signal quality factor can be measured to test the system performance It is evident that RDF and hybrid RDF + DFF has presented the highest signal quality factor and optical nonlinearity signal processing in compared with other optical fibers communication channel The obtained results were done using optiwave system software simulation version 7
TL;DR: In this article, the authors report the first long-haul coherent communication demonstration using a micro-resonator-based comb source, which achieved the longest fiber transmission ever achieved using an integrated comb source.
Abstract: Microresonator-based frequency combs are strong contenders as light sources for wavelength-division multiplexing (WDM). Recent experiments have shown the potential of microresonator combs for replacing a multitude of WDM lasers with a single laser-pumped device. Previous demonstrations have however focused on short-distance few-span links reaching an impressive throughput at the expense of transmission distance. Here we report the first long-haul coherent communication demonstration using a microresonator-based comb source. We modulated polarization multiplexed (PM) quadrature phase-shift keying-data onto the comb lines allowing transmission over more than 6300 km in a single-mode fiber. In a second experiment, we reached beyond 700 km with the PM 16 quadrature amplitude modulation format. To the best of our knowledge, these results represent the longest fiber transmission ever achieved using an integrated comb source.
TL;DR: In this paper, photonic crystal ring resonators with hexagonal lattice structure are used to design a four-channel optical demultiplexer, which can be used in dense wavelength division multiplexing (DWDM) systems.
Abstract: In this paper, photonic crystal ring resonators with hexagonal lattice structure are used to design a four-channel optical demultiplexer. The structure size, the average transfer coefficient, the quality factor, and the channel spacing are equal to 424.5 µm2, 95.8%, 1943, and 2 nm, respectively. The average crosstalk is also computed to be −18.11 dB. In this study, the plane wave expansion (PWE) and finite-difference time-domain (FDTD) methods are used, respectively, to characterize the photonic bandgap and to investigate the optical behavior of the structure. The proposed design can be used in dense wavelength division multiplexing (DWDM) systems.
02 Jul 2017
TL;DR: This system can achieve an aggregate data rate of 10 Gb/s over the entire proposed room with bit error rate (BER) = 10−6 and a simple modulation technique: on-off-keying (OOK).
Abstract: Achieving high data rate is one of the primary goals of visible light communication (VLC) systems. This paper introduces a VLC system based wavelength division multiplexing (WDM) to achieve a high data rate. In this work, red, yellow, green and blue (RYGB) laser diodes (LDs) are used as transmitters to obtain high modulation bandwidth and an imaging diversity receiver (IMDR) is used as an optical receiver. Based on the location of the IMDR, each colour of the RYGB LDs sends a different data stream at a different rate. Each pixel of the IMDR is covered by a specific colour optical filter. In this work, a multispectral colour filter array (MCFA) is assumed to design the pattern of the array colour filters of the IMDR. In this paper, we consider the effect of the diffusing reflections and mobility on the performance of the proposed system. This system can achieve an aggregate data rate of 10 Gb/s over the entire proposed room with bit error rate (BER) = 10−6 and a simple modulation technique: on-off-keying (OOK).
TL;DR: This work presents nonlinear impairment mitigation of wavelength division multiplexed signals, through optical phase conjugation (OPC), and demonstrates the operation of the system using both 16 and 64-quadrature amplitude modulation (QAM) signals.
Abstract: We present nonlinear impairment mitigation of wavelength division multiplexed signals, through optical phase conjugation (OPC). We conduct our experiments on a 400-km-long installed fiber link equipped with erbium-doped fiber amplifiers, with the OPC placed close to the middle of the link. Our OPC configuration realizes efficient reuse of the signal bandwidth, avoiding the loss of half of the spectral band typical of most phase conjugating schemes. We demonstrate the operation of the system using both 16- and 64-quadrature amplitude modulation (QAM) signals and report Q-factor improvements up to 0.5 and 2.5 dB for 16- and 64-QAM, respectively.
TL;DR: In this paper, a two dimensional (2D) PC-based eight channel demultiplexer is proposed and designed and the functional characteristics of demULTiplexers namely resonant wavelength, transmission efficiency, quality factor, spectral width, channel spacing and crosstalk are investigated.
Abstract: Recent years, the design of photonic crystal (PC) based optical devices is receiving keen interest in research and scientific community In this paper, two dimensional (2D) PC based eight channel demultiplexer is proposed and designed and the functional characteristics of demultiplexer namely resonant wavelength, transmission efficiency, quality factor, spectral width, channel spacing and crosstalk are investigated The demultiplexer is designed to drop the wavelength centred at 15376 nm, 15385 nm, 15394 nm, 15404 nm, 15412 nm, 15419 nm, 15426 nm and 15431 nm The proposed demultiplexer is primarily composed of bus waveguide, drop waveguide and quasi square ring resonator The quasi square ring resonator and square ring micro cavity (inner rods) are playing a vital role for a desired channel selection The operating range of the devices is identified through a photonic band gap (PBG) which is obtained using a plane wave expansion (PWE) method The functional characteristics of the proposed demultiplexer are attained using a 2D finite difference time domain (FDTD) method The proposed device offers low crosstalk and high transmission efficiency with ultra-compact size, hence, it is highly desirable for DWDM applications
TL;DR: Spectrum Slicing Wavelength Division Multiplexing (SS-WDM) has been advanced to boost the long distance communication in FSO channel which assists immense bit rate due to its high capacity and efficiency.
TL;DR: In this paper, a square-lattice photonic crystal fiber based on optofluidic infiltration technique is proposed for supercontinuum generation, without nano-scale variation in the geometry of the photonic fiber, ultra-flattened near zero dispersion centered about 1500 nm will be achieved.
Abstract: In this paper, a square-lattice photonic crystal fiber based on optofluidic infiltration technique is proposed for supercontinuum generation. Using this approach, without nano-scale variation in the geometry of the photonic crystal fiber, ultra-flattened near zero dispersion centered about 1500 nm will be achieved. By choosing the suitable refractive index of the liquid to infiltrate into the air-holes of the fiber, the supercontinuum will be generated for 50 fs input optical pulse of 1550 nm central wavelength with 20 kW peak power. We numerically demonstrate that this approach allows one to obtain more than two-octave spanning of supercontinuum from 800 to 2000 nm. The spectral slicing of this spectrum has also been proposed as a simple way to create multi-wavelength optical sources for dense wavelength division multiplexing.
TL;DR: This paper presents penalty-free bit error ratio results down to $10^{-12}$ from system tests on 200 meters of 8-core multicore fiber with fan-outs and up to 2 km in dual-core multipurpose fiber with connectors and fan-out.
Abstract: Many technical capabilities of space division multiplexed systems like low loss and crosstalk have been established in numerous long-haul system experiments. Recently more attention has been given to applications of space division multiplexing for short reach systems, including data center transmission and sensing applications. Short reach systems may be the first high volume application, as space division multiplexing for short reach systems has fewer remaining technical challenges. In addition to higher bandwidth density, space division multiplexed systems offer potential advantages in lower power consumption and cost. In this paper we present penalty-free bit error ratio results down to $10^{-12}$ from system tests on 200 meters of 8-core multicore fiber with fan-outs and up to 2 km in dual-core multicore fiber with connectors and fan-outs.
TL;DR: A general approach that leverages machine learning to characterize and mitigate the power excursions of EDFA systems with different equipment and scales is introduced and an ML engine is developed and experimentally validated to show accurate predictions of the power dynamics in cascaded EDFAs.
Abstract: Dynamic optical networking has promising potential to support the rapidly changing traffic demands in metro and long-haul networks. However, the improvement in dynamicity is hindered by wavelength-dependent power excursions in gain-controlled erbium doped fiber amplifiers (EDFA) when channels change rapidly. We introduce a general approach that leverages machine learning (ML) to characterize and mitigate the power excursions of EDFA systems with different equipment and scales. An ML engine is developed and experimentally validated to show accurate predictions of the power dynamics in cascaded EDFAs. Recommended channel provisioning based on the ML predictions achieves within 1% error of the lowest possible power excursion over 94% of the time. We also showcase significant mitigation of EDFA power excursions in super-channel provisioning when compared to the first-fit wavelength assignment algorithm.
TL;DR: In this article, an eight-state continuous-variable quantum key distribution (CV-QKD) over atmospheric turbulence channels was proposed. But the authors only considered the case of mean channel transmittances, and the minimum transmittance of 0.24 and 0.26 were required for OAM states of 2 (or −2) and 6 (or -6) respectively to guarantee the secure transmission.
Abstract: We experimentally demonstrate an eight-state continuous-variable quantum key distribution (CV-QKD) over atmospheric turbulence channels. The high secret key rate (SKR) is enabled by 4-D multiplexing of 96 channels, i.e., six-channel wavelength-division multiplexing, four-channel orbital angular momentum multiplexing, two-channel polarization multiplexing, and two-channel spatial-position multiplexing. The atmospheric turbulence channel is emulated by a spatial light modulator on which a series of azimuthal phase patterns yielding Andrews’ spectrum are recorded. A commercial coherent receiver is implemented at Bob's side, followed by a phase noise cancellation stage, where channel transmittance can be monitored accurately and phase noise can be effectively eliminated. Compared to four-state CV-QKD, eight-state CV-QKD protocol potentially provides a better performance by offering higher SKR, better excess noise tolerance, and longer secure transmission distance. In our proposed CV-QKD system, the minimum transmittances of 0.24 and 0.26 are required for OAM states of 2 (or –2) and 6 (or –6), respectively, to guarantee the secure transmission. A maximum SKR of 3.744 Gb/s is experimentally achievable, while a total SKR of 960 Mb/s can be obtained in case of mean channel transmittances.
TL;DR: In this article, the results of a field trial carried out on a Telecom Italia metro link, targeting short data center interconnect applications, were reported, with a net bit rate of 400 Gb/s on a single carrier with 64 quadrature amplitude modulation (QAM) and 128QAM over 156 km.
Abstract: We report on the results of a field trial carried out on a Telecom Italia metro link, targeting short data center interconnect applications. The test-bed presented realistic transmission conditions, such as an average ~0.3-dB/km attenuation and usage of legacy erbium-doped fiber amplifier (EDFA) only. We transmitted a net bit rate of 400 Gb/s on a single carrier with 64 quadrature amplitude modulation (QAM) and 128QAM over 156 km. Error-free transmission over 80 km for single carrier dense wavelength-division multiplexing (DWDM) $30\times 400\text{G}$ 64QAM and $30\times 400\text{G}$ 128QAM (one half of the $C$ -band) is reported. The net spectral efficiency, for both schemes, is 7.11 b/s/Hz.
TL;DR: In this paper, a real-time 100-Gb/s coherent transceiver with a simplified digital signal processing suitable for access spans, and a new automatic-gain-controlled erbium-doped fiber amplifier based preamplifier with an amplified spontaneous emission compensation function for the upstream to improve the minimum receiver sensitivity for coherent detection, especially at very low received signal power.
Abstract: In this paper, we present the first 100-Gb/s/ λ -based coherent wavelength division multiplexing passive optical network (WDM-PON) prototype system, highlighting a real-time 100-Gb/s coherent transceiver with a simplified digital signal processing suitable for access spans, and a new automatic-gain-controlled erbium-doped fiber amplifier based preamplifier with an amplified spontaneous emission compensation function for the upstream to improve the minimum receiver sensitivity for coherent detection, especially at very low received signal power. Thanks to our proposed technologies, this first demonstration achieved an increased bidirectional loss budget of more than 39.1 dB, which supports 80 km transmission with eight optical network unit splits, with an improved upstream receiver sensitivity of –38.1 dBm. In addition, to show the feasibility of the proposed 100-Gb/s/ λ -based coherent WDM-PON as a promising candidate for forthcoming 5G mobile fronthaul networks, we further investigate experimentally a 128-kb/s auxiliary management and control channel (AMCC) superimposed on the 100-Gb/s dual polarization quadrature phase-shift keying (DP-QPSK) signals employed by the 100-Gb/s/ λ -based coherent WDM-PON system. By setting the modulation index of the AMCC signals between 5% and 40%, we also successfully demonstrated 100-Gb/s DP-QPSK signal transmission with only a small power penalty of 0.2 dB due to the introduction of the AMCC signal.