Mode Group Division Multiplexing Research Articles

Dynamic analysis of PAM-4 IM/DD OAM-based MGDM transmission enabled by mode-group filter approach.

Mode-group-division multiplexing (MGDM)-based intensity modulation direct detection (IM/DD) transmission is an attractive approach to increase the capacity for short-reach optical communication. In this Letter, a simple but versatile scheme of mode group (MG) filtering for MGDM IM/DD transmission is proposed. The scheme is applicable to any mode basis in the fiber, and it satisfies the needs of low complexity, low power consumption, and high system performance. By employing the proposed MG filter scheme, a total raw bit rate of a 152-Gb/s multiple-input-multiple-output (MIMO)-free IM/DD co-channel simultaneous transmit and receive system based on two orbital angular momentum (OAM) MGs, each carrying a 38-GBaud four-level pulse amplitude modulation (PAM-4) signal, is experimentally demonstrated over a 5-km few-mode fiber (FMF). The bit error ratios (BERs) of the two MGs are below the 7% hard-decision forward error correction (HD-FEC) BER threshold at 3.8×10-3, using simple feedforward equalization (FFE). Furthermore, the dependability and robustness of such MGDM links are of great significance. Thus, the dynamic evaluation of BER and signal-to-noise ratio (SNR) for each MG is tested over 210 minutes under different conditions. In the dynamic cases, all the BER results using the proposed scheme can be below 1×10-3, which further confirms the stability and feasibility of our proposed MGDM transmission scheme.

Mode Group Division Multiplexing in 5 Mode-Group FMF Enabling MIMO-Free Solutions

We propose mode-group (MG) division multiplexing in a MIMO-free configuration to increase the capacity and the flexibility in reduced-complexity spatial division multiplexed metro networks. We take in account innovative few mode fibers (FMFs) supporting a large number of spatial modes, which allow to select suitable combinations of MGs providing limited crosstalk. Network provisioning in metro rings is investigated starting from experiments with up to 48-Tb/s capacity in a 5 MG FMF employing also a purposely developed quality of transmission tool.

Mode-Group Division Multiplexing: Transmission, Node Architecture, and Provisioning

Few Mode Fibers (FMF) and Space DivisionMultiplexing (SDM) are an attractive solution to offer high capacity in optical networks. Although transmission along FMF presents several issues mainly due to the cross-talk among modes, the use of Multiple Input Multiple Output (MIMO) coherent receivers permits to limit the impact of such physical impairment. However, the complexity of MIMO is not negligible (especially with a large number of modes) and the spatial modes must cover the same path, thus limiting network flexibility, e.g., routing modes along different paths is not admitted. In this paper we exploit the concept of Mode-Group Division Multiplexing (MGDM) and we investigate the network architecture and provisioning supporting MGDM. Modes are divided in groups: the modes within a group are co-routed and received with a reduced-complexity MIMO receiver, while the different groups can be routed along different paths. Different node architectures supporting MGDM are presented taking in account state-of-the-art components and devices, even commercially available on the market. A quality of transmission (QoT) model is also presented accounting to the inter mode group crosstalk, that cannot be neglected in the reach evaluation. QoT is exploited by a proposed connection provisioning scheme for MGDM. Simulations are carried out in metro/rural network scenarios with different link span lengths. Simulations show high throughput increase while limiting the complexity of receivers.

Millimeter-wave enabled PAM-4 data transmission over hybrid FSO-MMPOF link for access networks

In this paper, we propose a full duplex architecture based on a hybrid link composed of free space optics (FSO) and multimode plastic optical fiber (MMPOF) for short-range wireless access networks. The proposed architecture employs mode group division multiplexing (MGDM) and wavelength reuse techniques to transmit data between central unit (CU) and radio access units (RAUs). An optical frequency comb source to generate multiple optical sidebands is realized using a single laser source to provide 60 GHz millimeter-wave (mm-wave) signals at each RAU by simultaneously transmitting PAM-4 signal on linearly polarized (LP) modes of each optical sideband. Data rate of 2times12 Gbps at mm-wave frequency of 60 GHz is achieved for both downlink (DL) and uplink (UL) transmissions. The transmission of 2times12 Gbps PAM-4 signal over hybrid FSO-MMPOF link is investigated at different values of refractive index structure parameter (C_n^2) by employing log-normal (LN) FSO channel model to support three RAUs in a ring topology. The acceptable receiver sensitivities below −5 and −0.6 dBm for DL and UL transmissions are achieved, respectively. The proposed hybrid architecture can be a potential candidate for future communication networks.

Simple SSMF-based two-channel MGDM system operating in the 0.8 µm wavelength region.

We propose a simple two-channel mode-group-division-multiplexing (MGDM) system operating in the 0.8 µm region over the standard single-mode fiber (SSMF). For the cost-effectiveness, we implement its receiver by using only two photodetectors (PDs) [instead of three PDs required for the detection of the LP01,LP11a, and LP11b modes]. We then detect the signal carried by the LP01 mode by using a PD and a mode filter. On the other hand, the other signal carried by the LP11 mode group is detected by using another PD and a multiple-input single-output equalizer (i.e., by subtracting the signal carried by the LP01 mode from the multiplexed signal). For a demonstration, we transmit 2×28Gb/s MGDM on-off keying signal operating at 852.6 nm over 2.2 km of the SSMF by using the proposed technique. The results show that we can achieve the bit-error rate of <3.8×10-3 for both the LP01 and LP11 modes.

基于预编码的模群复用信号串扰抵消技术

基于预编码的模群复用信号串扰抵消技术

Linearly polarised modes enabled PAM‐4 data transmission over few‐mode fibre for data centre interconnect

This Letter proposes a high data rate optical transmission system for data centre interconnects, where the authors employ vertical cavity surface emitting lasers (VCSEL) and graded index few-mode fibre (GI-FMF) having modal bandwidth of around 24.3 GHz.km to enhance the link capacity and range. Additionally, they consider PAM-4 modulated data transmission at the rate of 2 100 Gbps using a pair of VCSELs and employing mode group division multiplexing of two linearly polarised (LP) modes and of the GI-FMF. Digital signal processing techniques are applied at the receiver to process the received PAM-4 signals for equalisation in order to mitigate the channel impairments. Furthermore, standard OM3 and OM4 fibres are considered as a benchmark to compare the transmission performance of the designed GI-FMF. They observe that the designed GI-FMF supports longer transmission distance for both and modes upto 900 and 450 m at 50 and 100 Gbps data rates, respectively, while achieving lower receiver sensitivities for forward error correction limit of . The proposed optical transmission system can be a potential applicant in future data centre networks supporting transmission rates in 800 Gbps to 1.6 Tbps range.

Terabit Mode Division Multiplexing Discrete Multitone Signal Transmission Over OM2 Multimode Fiber

In this paper, we experimentally demonstrated Tb/s mode division multiplexed (MDM) transmission over 20m OM2 multimode fiber (MMF) using three linearly polarized modes, wavelength division multiplexing, intensity modulation and direct detection (IM-DD). The multi-plane light conversion (MPLC) based mode multiplexer/demultiplexer were adopted and its performance has been characterized. Three mode channels with the mode crosstalk less than −20 dB were selected to implement the MDM-MMF based transmission. Each mode channel was modulated by discrete Fourier transform spread discrete multi-tone (DFT-S DMT) scheme with 2048 subcarriers via 40 GHz Mach-Zehnder modulator (MZM). We obtained the error-free transmission of 135 Gb/s per mode per wavelength and total 1.62 Tb/s WDM-MDM below the forward error correction (FEC) limit of 3.8 × 10−3 at the received optical power (ROP) of > − 4.5 dBm with 86 GSa/s digital to analog converter (DAC). To the best of our knowledge, it is the highest bit rate per channel for the MDM based on conventional OM2 fiber transmission rather than the mode group division multiplexing (MGDM) based with cost-effective IM-DD and no multiple-in-multiple-out (MIMO) technology. The experimental results show that the MDM-MMF based transmission has the potential in the high-speed large-capacity short-reach optical interconnects.

Study of Optical MIMO Transmission Systems Using the MGDM Multiplexing Technique

In current local area networks, multimode fibers (MMFs), mainly graded index (GI) MMFs, are the main types of fibers used for data communications. Because of their high bandwidth, they are considered the main method of transmission that allows to offer multiservice broadband services using optical multiplexing techniques.&#x0D; &#x0D; The MGDM (ModeGroup Division Multiplexing) is a Multiplexing technique, which aims to improve the performance of the multimode optical fiber by spatially multiplexing the data streams to be transmitted. In this work, we study optical MIMO (multi-input multi-output) transmission systems on an MMF optical fiber, specifically the adaptation of the architecture of MIMO transmission systems. In this context, we have studied the mode group multiplexing technique (MDGM), to evaluate the transmission capacity. In fact, the latter depends on the injection conditions and the state of the optical fiber.

Power Loading in Peak Limited Intensity Modulation Direct Detection Mode Group Division Multiplexing

The exponential growth of network traffic within data centers and high-performance computing generates a growing volume of fiber cabling. This raises the need for spectrally efficient communication scheme, which allows easy integration of optics and electronics. In this paper, we suggest a mode group division multiplexing scheme based upon intensity-modulated silicon photonics (SiP) Mach-Zehnder modulators (MZMs) coupled to standard graded-index multi-mode fiber directly detected using multi-segment concentric photo-detector. In addition, we have theoretically derived the bit and power loading of such a system in a closed-loop multiple-input multiple-output (MIMO) formation using convex optimization with two possible types of architectures: the vertical Bell Labs layered space-time architecture (V-BLAST) with minimum mean square error and successive interference cancellation (MMSE-SIC); and singular value decomposition (SVD). Our optimization problem maximizes the system's capacity under peak amplitude, power consumption, and BER constraints. Simulation results have shown the superiority of a V-BLAST MMSE-SIC over the SVD architecture in terms of total spectral efficiency for a 4 × 4 MIMO short reach low driving voltage conventional SiP-based MZM system.

MIMO-enabled integrated MGDM–WDM distributed antenna system architecture based on plastic optical fibers for millimeter-wave communication

Design of a low-cost fiber–wireless communication architecture is desirable by network operators. Therefore, we demonstrate the transmission of $$2 \times 2$$ MIMO spatial streams, each having 2 Gbps DPSK signal to two different radio access units (RAUs) in a distributed antenna system architecture. The proposed architecture employs mode group division multiplexing in combination with wavelength division multiplexing to transport RF DPSK signals centered at 10 GHz. The RF signals are used to modulate optical carriers that are centered at 1300 nm and transmitted toward the RAUs over perfluorinated graded-index plastic optical fiber. Heterodyne detection is performed at the RAUs to transmit mm-wave signals at 60 GHz to the end users. Furthermore, wireline access is also achieved at each RAU to support simplex services. A cost-efficient multiple wavelength source is generated from a single laser by employing a dual-drive Mach–Zehnder modulator. An increase in multiplexing gain is achieved using the two LP modes, LP01 and LP11, of each generated wavelength. The proposed architecture gives acceptable BER results for practical implementation.

Intra-group principal modes in graded-index multimode fibers used for mode group division multiplexing transmission

By considering very strong intra-group mixing while neglecting inter-group mixing in mode group division multiplexing (MGDM) transmission, we theoretically introduce and describe the physical model of intra-group principal modes (IGPMs) in graded-index (GI) multimode fibers (MMFs), from the view of fiber transmission matrices for both cases of one- and dual-polarization. Proof-of-concept numerical calculations for an exemplary mode-group-channel with the two lowest-order degenerate mode groups (namely the three lowest-order fiber eigenmodes) show that IGPMs can exhibit potential possibilities of the MGDM channel with minimal mode mixing/dispersion-induced signal distortion over a GI MMF.

4×10 Gbit/s bidirectional transmission over 2 km of conventional graded-index OM1 multimode fiber using mode group division multiplexing.

We demonstrate 4 × 10 Gbit/s error-free bidirectional transmission over 2 km of conventional OM1 graded-index multimode fiber using OOK modulation and direct detection. We also perform field transmission to show reach and capacity boosts on legacy multimode infrastructure. Such transmission is enabled by selective mode group division multiplexing, based on multi-plane light conversion over 4 mode groups of the multimode fiber.

Characterization and applications of spatial mode multiplexers based on Multi-Plane Light Conversion

Abstract Multi-Plane Light Conversion (MPLC) enables novel beam shaping devices, and in particular highly mode-selective spatial mode multiplexers. MPLC-based multiplexers can combine up to 10 spatial modes with cross-talk of −26 dB and insertion loss below 4 dB. These multiplexers are versatile and can be used in many applications, including long haul mode division multiplexing, short reach mode group division multiplexing, multi-mode optical amplification, and their mode conversion capabilities can be used for optimizing wavelength selective switches.

Mode group division multiplexing in graded-index multimode fibers

Data transmission over multimode fibers has the potential to considerably increase the capacity limit of single-mode fibers by exploiting the spatial dimension. For long-haul systems, mode division multiplexing using one mode per channel in a few-mode fiber requires coherent detection in conjunction with digital multiple input multiple output (MIMO) processing for signal separation. In the following we focus on spatial multiplexing using mode groups rather than spatial modes in standard graded-index multimode fibers. In combination with on-off keying (OOK) modulation and direct detection, these systems might be advantageous for access- and connection-related applications, e.g., for super computer interconnects or in the near metro region at link lengths shorter than about 10 km. In this paper we study the potential of mode groups for mode group division multiplexing (MGDM). Single-mode group transmission experiments at 10 Gb/s per mode group, experimental mode group launching by phase mask, and concepts for passive optical mode demultiplexers are discussed.

Holographic Offset Launch for Dynamic Optimization and Characterization of Multimode Fiber Bandwidth

Optimization of the bandwidth of a 2 km 50 μm multimode fiber at 850 nm is investigated theoretically and experimentally by steering a single spot, or two in antiphase spots across the core of the fiber in two dimensions using a ferroelectric liquid-crystal-based spatial light modulator. This method not only allows an optimal offset launch position to be chosen in situ but can also characterize the geometry and position of the core, identify defects, and measure the maximum differential mode delay. Its ability to selectively excite specific mode groups is also of relevance to mode-group division multiplexing.

30-Gb/s 3$\,\times\,$3 Optical Mode Group-Division-Multiplexing System With Optimized Joint Detection

This letter investigates a 30-Gb/s 3 × 3 optical mode group-division-multiplexing (MGDM) system over graded index multimode fiber (GI-MMF). With mode-selective spatial filtering (MSSF), the optimized joint detection has been realized, which de creases the complexity of the signal processing to recover received signals.