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- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Fukuoka, Japan (2019.7.7-2019.7.11)] 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Stable Measurement of Near/Far Field Profiles of Coupled Multi-Core Fiber
摘要： A low-coherence method is presented for measuring stable near-field and far-field profiles of coupled multi-core fibers. Stability is achieved by averaging output intensity over wavelength to eliminate time-varying intensity fluctuations caused by coupling and interference.
关键词： Fiber characterization and measurement techniques,Fibers for space division multiplexing
更新于2025-09-16 10:30:52
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Advanced DSP for Coherent Optical Fiber Communication
摘要： In this paper, we provide an overview of recent progress on advanced digital signal processing (DSP) techniques for high-capacity long-haul coherent optical fiber transmission systems. Not only the linear impairments existing in optical transmission links need to be compensated, but also, the nonlinear impairments require proper algorithms for mitigation because they become major limiting factors for long-haul large-capacity optical transmission systems. Besides the time domain equalization (TDE), the frequency domain equalization (FDE) DSP also provides a similar performance, with a much-reduced computational complexity. Advanced DSP also plays an important role for the realization of space division multiplexing (SDM). SDM techniques have been developed recently to enhance the system capacity by at least one order of magnitude. Some impressive results have been reported and have outperformed the nonlinear Shannon limit of the single-mode fiber (SMF). SDM introduces the space dimension to the optical fiber communication. The few-mode fiber (FMF) and multi-core fiber (MCF) have been manufactured for novel multiplexing techniques such as mode-division multiplexing (MDM) and multi-core multiplexing (MCM). Each mode or core can be considered as an independent degree of freedom, but unfortunately, signals will suffer serious coupling during the propagation. Multi-input–multi-output (MIMO) DSP can equalize the signal coupling and makes SDM transmission feasible. The machine learning (ML) technique has attracted worldwide attention and has been explored for advanced DSP. In this paper, we firstly introduce the principle and scheme of coherent detection to explain why the DSP techniques can compensate for transmission impairments. Then corresponding technologies related to the DSP, such as nonlinearity compensation, FDE, SDM and ML will be discussed. Relevant techniques will be analyzed, and representational results and experimental verifications will be demonstrated. In the end, a brief conclusion and perspective will be provided.
关键词： coherent detection,neural network,space division multiplexing,digital signal processing,nonlinearity compensation,machine learning,optical fiber communication,equalization
更新于2025-09-16 10:30:52
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Single-shot Fresnel incoherent digital holography based on geometric phase lens
摘要： Single-shot and incoherent imaging are two important properties of digital holography that can extend its application range. In this study, a simple, compact, in-line Fresnel incoherent digital holographic recording system is proposed that is capable of single-shot and three-dimensional imaging. A geometric phase lens is used as the common-path beam splitter based on its special wave separation property. Parallel phase-shifting holography is used to achieve single-shot operation with the use of a polarization imaging camera together with space-division multiplexing. The capabilities of the proposed technique are experimentally confirmed by imaging two standard test charts based on a compact setup.
关键词： incoherent digital holography,Single-shot,three-dimensional imaging,Parallel phase-shifting method,space-division multiplexing,geometric phase lens
更新于2025-09-12 10:27:22
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Efficient Mode Multiplexer for Few-Mode Fibers Using Integrated Silicon-on-Insulator Waveguide Grating Coupler
摘要： We propose a novel and highly efficient multimode waveguide grating coupler which can simultaneously launch four channels including two polarizations of the linear polarized (LP) modes, LP01 and LP11 of a step-index few-mode fiber (FMF). The waveguide grating coupler on the silicon-on-insulator (SOI) platform is based on a subwavelength structure which was optimized using the genetic optimization approach with 2-dimensional finite-difference time-domain (2-D FDTD) simulations combined with the second?order effective medium theory (EMT). Simulations predicted the coupling efficiencies to be ?4.3 dB for LP01 mode and ?5.0 dB for the LP11 mode. The design was fabricated in a multi-project wafer (MPW) run for silicon photonics. Coupling efficiency of ?4.9 dB and ?6.1 dB was experimentally demonstrated for LP01 mode and LP11 mode, respectively. The proposed mode multiplexer is entirely passive and suitable for future applications with FMFs in space-division-multiplexing (SDM) networks.
关键词： few-mode fibers,space-division multiplexing,diffraction gratings,Integrated optics
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Multimode fibers
摘要： Multimode fibers were first used for nonlinear optics during the 1970s because most optical fibers available at that time supported multiple modes. The situation changed in the 1980s when single-mode fibers were commercialized in view of their telecommunication applications. The interest in multimode fibers re-surfaced after 2005, partly motivated by their use for space-division multiplexing in optical communication systems. As a byproduct of this interest, the nonlinear effects in multimode fibers have been studied extensively since 2010. This chapter covers recent advances in a systematic fashion. Three types of multimode fibers are introduced in Section 14.1, where we also discuss modes supported by them. Section 14.2 extends theory of Section 2.3 to obtain a set of coupled nonlinear equations for various fiber modes. These equations are used in Sections 14.3 to discuss modulation instability and soliton formation in multimode fibers. The focus of Section 14.4 is on the intermodal nonlinear effects that transfer energy among the modes. The spatio-temporal effects are discussed in Section 14.5 with emphasis on spatial beam cleanup and supercontinuum generation through multimode fibers. Section 14.6 is devoted to the nonlinear phenomena in multicore fibers.
关键词： modulation instability,spatio-temporal effects,spatial beam cleanup,soliton formation,multimode fibers,multicore fibers,supercontinuum generation,nonlinear optics,space-division multiplexing,intermodal nonlinear effects
更新于2025-09-12 10:27:22
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[IEEE 2018 International Topical Meeting on Microwave Photonics (MWP) - Toulouse (2018.10.22-2018.10.25)] 2018 International Topical Meeting on Microwave Photonics (MWP) - Spatial Diversity Gain of Micrometer-scale MIMO FSO Transceivers utilizing Multicore Fiber and 2-D Photodetector Array
摘要： Feasibility of a high-capacity spatially-multiplexed free-space optical (FSO) communications system utilizing small-footprint spatial diversity transceivers based on multicore fiber and 2-D photodetector array is investigated. With the aid of MIMO-DSP, the micrometer-scale spatial diversity transceivers enable 37-Gbps 2x4 MIMO-FSO transmission over strongly-correlated optical MIMO channels.
关键词： Free space optics MIMO,Space-division multiplexing,Spatial diversity,Optical wireless communication
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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Space division multiplexing in standard multi-mode optical fibers based on speckle pattern classification
摘要： In optical communications the transmission bandwidth of single mode optical fibers is almost fully exploited. To further increase the capacity of a telecommunication link, multiplexing techniques can be applied across 5 physical dimensions: amplitude, quadrature, polarization, frequency and space, with all but the latter being nearly exhausted. We experimentally demonstrate the feasibility of an original space division multiplexing technique based on the classification of speckle patterns measured at the fiber’s output. By coupling multiple optical signals into a standard multimode optical fiber, speckle patterns arise at the fiber’s end facet. This is due to quasi-random interference between the excited modes of propagation. We show how these patterns depend on the parameters of the optical signal beams and the fiber length. Classification of the speckle patterns allows the detection of the independent signals: we can detect the state (i.e. on or off) of different beams that are multiplexed in the fiber. Our results show that the proposed space division multiplexing on standard multimode fibers is robust to mode-mixing and polarization scrambling effects.
关键词： space division multiplexing,mode-mixing,speckle patterns,polarization scrambling,optical communications,multimode optical fibers
更新于2025-09-11 14:15:04
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[IEEE 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Sao Paulo, Brazil (2019.10.7-2019.10.9)] 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Few-Mode Erbium-Doped Fiber Amplifier Design Challenges for WDM Optical Networks
摘要： The use of optical spatial division multiplexing (SDM) technologies increases the capacity of the optical channel, allowing higher transmission rates than those observed in wavelength division multiplexing (WDM) optical systems based on single-mode fibers. In particular, spatial multiplexing based on multimode fibers allows the transmission of information in orthogonal modes. In these systems, the erbium-doped fiber amplifier (EDFA) remains essential to compensate for optical link losses. This paper presents the challenges to the development of EDFAs for WDM optical systems based on few-mode fibers, considering the addition of gain flattening filters and correction of gain calculation.
关键词： erbium-doped fiber amplifiers,space division multiplexing,gain equalization,Few-mode fiber amplifier
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