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Intercore Crosstalk Mitigation in Multicore Fiber Transmission with Optical Space Coding
摘要： We have demonstrated crosstalk mitigation in single-mode MCFs using optical space coding. Four types of single-mode multicore fiber (MCF) models were evaluated by our scheme with the modified prime code and differential detection. Typically, intercore crosstalk was improved by 7–20 dB in 9-core fibers with an original crosstalk of 10–20 dB.
关键词： OCDM,multicore fiber,crosstalk,intercore coupling
更新于2025-09-23 15:23:52
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10?Gbps CPRI signals transmission impaired by intercore crosstalk in 5G network fronthauls with multicore fibers
摘要： The impact of intercore crosstalk (ICXT) of weakly-coupled multicore fibers (MCFs) on the transmission performance of a Common Public Radio Interface (CPRI) signal in 5G networks fronthaul is studied by numerical simulation. The results show that forward error correction-supported CPRI signals have more tolerance to ICXT due to the higher targeted bit error rate (of 10?3). For a receiver power penalty of 1 dB, an improvement of the tolerance of CPRI signals to ICXT, due to the increase of the MCF skew by about 1 dB, is observed. However, for the crosstalk levels that lead to 1 dB power penalty, we have shown that, the system is unavailable with a high probability. The crosstalk level required for an acceptable outage probability is about 10 dB lower than the crosstalk level leading to 1 dB power penalty.
关键词： 5G wireless networks,Multicore fiber,Common public radio interface,Outage probability,Intercore crosstalk,Bit error rate
更新于2025-09-23 15:23:52
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Multicore Multimode Fiber-A New Type of Fiber Using Coupled-Core Structures
摘要： A new type of multimode fiber, multicore multimode fiber (MCMMF), which uses coupled multicore structure is proposed. The fiber has a large number of single mode cores with optimized coupling to achieve high bandwidth. A theoretical model for analyzing the MCMMF is developed. The effect of fiber parameters, such as index contrast, core radius, and core spacing on the bandwidth is systematically studied. Numerical simulations show that the bandwidth of a MCMMF can be optimized by choosing correct ratio of core spacing to core radius for a given profile design. In addition, mode coupling among the super-modes can further increase the bandwidth due to the small spacing in effective indices in coupled core structures. A MCMMF with 165 cores is fabricated. High bandwidth of 8.4 GHz·km in the 850 nm window is achieved. Using this fiber and a VCSEL-based 25 Gb/s SR transceiver, error free transmission though 150 m fiber is demonstrated.
关键词： fiber characterization,fiber bandwidth,data center,multimode fiber,Coupled multicore fiber,fiber design,fiber fabrication
更新于2025-09-23 15:21:01
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Method for increasing the core count and area of high density optical fiber bundles
摘要： Current manufacturing methods limit the increase in both core count and the area for optical fiber bundles. Here a method for increasing the core count and hence the available image area of high density optical fiber bundles, through fusing multiple smaller sized sub-bundles is proposed and experimentally investigated. The key issue being investigated is whether it is possible to eliminate or reduce the dead-space between cylindrical sub-bundles, where no cores are present to spatially sample an image. Small sample lengths of fused optical fiber bundles are fabricated and characterized using an optical and scanning electron microscope to assess the reduction in dead-space and the optical losses near the interfaces. We demonstrate a 30% decrease in the dead-space area through fusing three equally sized sub-bundles in a triangular arrangement, while still retaining the light-guiding ability of more than 70% of the cores which transported into this region. We also assessed the optical losses for cores near the fused interfaces, at different wavelengths in the visible spectrum. A model of the propagation modes supported by the cores is explored which attributes these losses to the increasing eccentricity of cores near the fused interfaces.
关键词： optical fiber imaging,Multicore fiber,linearly polarized modes,fiber fabrication and design
更新于2025-09-23 15:19:57
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Carrier Beating Impairment in Weakly Coupled Multicore Fiber-Based IM/DD Systems
摘要： Weakly coupled multicore fiber (WC-MCF) is promising for use in short-reach fiber telecommunication systems in the near future. Intercore crosstalk (XT) plays an important role in WC-MCF-based short-reach (IM/DD) systems, because XT can significantly degrade system performance. For the first time, the combined effect of intercore XT and the frequency offset between optical carriers, which is defined as the carrier beating impairment (CBI), is measured and characterized by experiments and numerical simulations. The experimental results show that the CBI causes large fluctuations in the signal-to-noise ratio (SNR) with a normally tolerable XT level. Such SNR fluctuations can additionally reduce the system’s XT tolerance (at worst 1-dB SNR degradation) by as much as 20 dB for 4-level pulse amplitude modulation (PAM-4) transmission. The simulation results show that the CBI is mainly affected by the specific properties of the laser source and the modulation depth of the transmitted signals. These results suggest that the XT should be designed to be much smaller for WC-MCF-based short-reach IM/DD systems when there is the CBI.
关键词： intercore crosstalk,optical carrier,Multicore fiber,telecommunication
更新于2025-09-19 17:13:59
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Stability of out-of-phase solitons and laser pulse self-compression in active multicore fibers
摘要： An out-of-phase soliton distribution of the wave ?eld is found for a multicore ?ber (MCF) from an even number of cores located in a ring. Its stability is proved with respect both to small wave-?eld perturbations, including azimuthal ones, and to small deformations of the MCF structure. As an example of using this soliton distribution, the problem of laser pulse compression in an active MCF is studied. The optimal ?ber parameters, the minimum duration of the output pulse, and the compression length are found, and they are in good agreement with the results of numerical simulation. In order to achieve high energies in the output laser pulse, the requirements for MCF deformations are determined.
关键词： fiber optics,laser pulse compression,soliton,multicore fiber,nonlinear optics
更新于2025-09-16 10:30:52
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Assessment of the Combined Effect of Laser Phase Noise and Intercore Crosstalk on the Outage Probability of DD OOK Systems
摘要： We study the influence of the combined effect of laser phase noise and intercore crosstalk on the outage probability of direct-detection 10 Gbit/s on-off keying optical communication systems. We show that the laser phase noise can affect significantly the outage probability, for lasers with linewidths in the MHz range, for low and high skew-bit rate products. We also show that the laser phase noise effect on the received eye-pattern is qualitatively similar to the one found for high skew-bit rate product in the absence of laser phase noise.
关键词： intercore crosstalk,on-off keying,multicore fiber,laser phase noise,outage probability
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Twin Multicore Fiber Interferometers for Precision Sensing
摘要： Multicore fiber (MCF) sensors is an emerging research field. MCFs provide new alternatives for the development of innovative sensing devices whose performance cannot be achieved with conventional optical fibers. In general, MCFs have diameters similar to that of a standard single mode fiber (SMF) and have multiple individual cores sharing a common cladding. So far, a number of sensors based on MCF have been reported. Our group, for example, has reported different sensors based on single MCF interferometers that consist of a piece of MCF spliced to SMF [1,2]. One key issue of such sensors is the difficulty of discriminating the target parameter (measurand) from unwanted external perturbations that may be present during the use of the sensor. To address this issue, here, we introduce an innovative architecture that consists of two identical (twin) MCF interferometers in series that are interrogated in reflection mode, see Fig. 1. Our architecture has important advantages. As there are two MCF interferometers, one can be used as a reference or filter and the other as a sensor [3]. The signal of our twin MCF interferometers is the multiplication of individual reflection spectra. Consequently, their reflection exhibits a single narrow peak whose position in wavelength is easy to track. We have observed that periodic bending (vibrations) in one them resulted in prominent shifts in the reflection spectrum.
关键词： precision sensing,vibration sensors,interferometers,Multicore fiber,bending sensors
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - Probability Distribution of Intercore Crosstalk in Weakly Coupled MCFs with Multiple Interferers
摘要： The statistical behavior of the intercore crosstalk (ICXT) power in weakly coupled multicore fibers (MCFs) with multiple interfering cores is experimentally assessed. The histograms with multiple interfering cores are compared with the probability density function (pdf) of the quadratic form corresponding to the ICXT power considering different correlation coefficients between the in-phase and quadrature Gaussian ICXT field components of the orthogonal polarizations. A very good fitting between experimental histograms and the numerical pdf of the quadratic form occurs when the ICXT field components are modeled as uncorrelated random processes. These results demonstrate that the ICXT power can, with a very low error, be described by a chi-square distribution with 4 degrees of freedom not only with a single interfering core but also with multiple interfering cores. This means that the ICXT contributions induced by different cores of the MCF are uncorrelated.
关键词： Multicore fiber,probability density function,space division multiplexing,multiple interferers
更新于2025-09-11 14:15:04
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Enabling Simultaneous DAS and DTS Through Space-Division Multiplexing Based on Multicore Fiber
摘要： We have proposed and demonstrated a hybrid optical-fiber sensor that enables simultaneous distributed acoustic sensing (DAS) and distributed temperature sensing (DTS). The hybrid fiber sensor is realized through space-division multiplexed (SDM) reflectometers in a multicore fiber (MCF), where Raman optical time-domain reflectometry (ROTDR) for DTS is implemented simultaneously with phase-sensitive optical time-domain reflectometry (Φ-OTDR) for DAS through space-division multiplexing. The SDM reflectometers share an identical pulse source, but use separate interrogation fiber cores, allowing simultaneous measurement of ROTDR and Φ-OTDR. The proposed hybrid sensor based on MCF does not suffer from the incompatible pump power levels issue existing in its counterpart based on single mode fiber thanks to the SDM implementation. Thus it effectively eliminates the restriction imposed by fiber nonlinear effects (e.g., modulation instability). Wavelet transform denoising method is employed to reduce the noise of temporal ROTDR traces; as a result, the worst temperature uncertainty is reduced from 4.1 to 0.5 °C over 5.76 km sensing range. The proposed SDM hybrid fiber sensor can realize simultaneous distributed intrusion detection and temperature monitoring. It offers great potential in long-term real-time pipeline monitoring for oil and gas industry.
关键词： Distributed acoustic sensing,multicore fiber,distributed temperature sensing,space-division multiplexing
更新于2025-09-11 14:15:04