336 research outputs found
Performance Assessment of Dual-Polarized 5G Waveforms and Beyond in Directly Modulated DFB-Laser using Volterra Equalizer
International audienceWe investigate the performance of 25-Gbps dual-polarized orthogonal frequency division multiplexing (OFDM)-based modulation in a directly modulated distributed feedback (DFB)-laser over 25 km of single-mode fiber. A Volterra equalizer is used to compensate for the nonlinear effects of the optical fiber. The results show that FBMC-OQAM modulation outperforms OFDM, universal filtered multicarrier (UFMC), and generalized frequency division multiplexing (GFDM) waveforms. Indeed, a target bit error rate of similar to 3.8 x 10(-3) [forward error correction (FEC) limit] for FBMC, UFMC, OFDM, and GFDM can be achieved at -30.5, -26, -16, and -14.9 dBm, respectively. The effect of the DFB laser is also investigated for UFMC, OFDM, and GFDM, and they undergo a Q penalty of 2.44, 2.77, and 4.14 dB, respectively, at their FEC limit points. For FBMC-OQAM, the signal is perfectly recovered when excluding the DFB laser at -30.5 dBm. (C) 2020 Society of Photo-Optical Instrumentation Engineers (SPIE
A survey on fiber nonlinearity compensation for 400 Gbps and beyond optical communication systems
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.Comment: Accepted in the IEEE Communications Surveys and Tutorial
Chip-based Brillouin processing for carrier recovery in coherent optical communications
Modern fiber-optic coherent communications employ advanced
spectrally-efficient modulation formats that require sophisticated narrow
linewidth local oscillators (LOs) and complex digital signal processing (DSP).
Here, we establish a novel approach to carrier recovery harnessing large-gain
stimulated Brillouin scattering (SBS) on a photonic chip for up to 116.82
Gbit/sec self-coherent optical signals, eliminating the need for a separate LO.
In contrast to SBS processing on-fiber, our solution provides phase and
polarization stability while the narrow SBS linewidth allows for a
record-breaking small guardband of ~265 MHz, resulting in higher
spectral-efficiency than benchmark self-coherent schemes. This approach reveals
comparable performance to state-of-the-art coherent optical receivers without
requiring advanced DSP. Our demonstration develops a low-noise and
frequency-preserving filter that synchronously regenerates a low-power
narrowband optical tone that could relax the requirements on very-high-order
modulation signaling and be useful in long-baseline interferometry for
precision optical timing or reconstructing a reference tone for quantum-state
measurements.Comment: Part of this work has been presented as a postdealine paper at CLEO
Pacific-Rim'2017 and OSA Optic
Optics for AI and AI for Optics
Artificial intelligence is deeply involved in our daily lives via reinforcing the digital transformation of modern economies and infrastructure. It relies on powerful computing clusters, which face bottlenecks of power consumption for both data transmission and intensive computing. Meanwhile, optics (especially optical communications, which underpin todayâs telecommunications) is penetrating short-reach connections down to the chip level, thus meeting with AI technology and creating numerous opportunities. This book is about the marriage of optics and AI and how each part can benefit from the other. Optics facilitates on-chip neural networks based on fast optical computing and energy-efficient interconnects and communications. On the other hand, AI enables efficient tools to address the challenges of todayâs optical communication networks, which behave in an increasingly complex manner. The book collects contributions from pioneering researchers from both academy and industry to discuss the challenges and solutions in each of the respective fields
Hybrid Free-Space Optical and Visible Light Communication Link
V souÄastnosti bezdrĂĄtovĂ© optickĂ© komunikace (optical wireless communication, OWC) zĂskĂĄvajĂ ĆĄirokou pozornost jako vhodnĂœ doplnÄk ke komunikaÄnĂm pĆenosĆŻm v rĂĄdiovĂ©m pĂĄsmu. OWC nabĂzejĂ nÄkolik vĂœhod vÄetnÄ vÄtĆĄĂ ĆĄĂĆky pĆenosovĂ©ho pĂĄsma, neregulovanĂ©ho frekvenÄnĂho pĂĄsma Äi odolnosti vĆŻÄi elektromagnetickĂ©mu ruĆĄenĂ. Tato prĂĄce se zabĂœvĂĄ nĂĄvrhem OWC systĂ©mĆŻ pro pĆipojenĂ koncovĂœch uĆŸivatelĆŻ. SamotnĂĄ realizace spojenĂ mĆŻĆŸe bĂœt provedena za pomoci rĆŻznĂœch variant bezdrĂĄtovĂœch technologiĂ, napĆĂklad pomocĂ OWC, kombinacĂ rĆŻznĂœch OWC technologiĂ nebo hybridnĂm rĂĄdio-optickĂœm spojem. Za ĂșÄelem propojenĂ tzv. poslednĂ mĂle je analyzovĂĄn optickĂœ bezvlĂĄknovĂœ spoj (free space optics, FSO). Tato prĂĄce se dĂĄle zabĂœvĂĄ analĂœzou pĆenosovĂœch vlastnostĂ celo-optickĂ©ho vĂce skokovĂ©ho spoje s dĆŻrazem na vliv atmosfĂ©rickĂœch podmĂnek. V dneĆĄnĂ dobÄ mnoho uĆŸivatelĆŻ trĂĄvĂ Äas ve vnitĆnĂch prostorech kancelĂĄĆĂ Äi doma, kde komunikace ve viditelnĂ©m spektru (visible light communication, VLC) poskytuje lepĆĄĂ pĆenosovĂ© parametry pokrytĂ neĆŸ Ășzce smÄrovĂ© FSO. V rĂĄmci tĂ©to prĂĄce byla odvozena a experimentĂĄlnÄ ovÄĆena zĂĄvislost pro bitovou chybovost pĆesmÄrovanĂ©ho (relaying) spoje ve VLC. Pro propojenĂ poskytovatele datavĂœch sluĆŸeb s koncovĂœm uĆŸivatelem mĆŻĆŸe bĂœt vĂœhodnĂ© zkombinovat vĂce pĆenosovĂœch technologiĂ. Proto je navrĆŸen a analyzovĂĄm systĂ©m pro pĆekonĂĄnĂ tzv. problĂ©mu poslednĂ mĂle a poslednĂho metru kombinujĂcĂ hybridnĂ FSO a VLC technologie.The field of optical wireless communications (OWC) has recently attracted significant attention as a complementary technology to radio frequency (RF). OWC systems offer several advantages including higher bandwidth, an unregulated spectrum, resistance to electromagnetic interference and a high order of reusability. The thesis focuses on the deployment and analyses of end-user interconnections using the OWC systems. Interconnection can be established by many wireless technologies, for instance, by a single OWC technology, a combination of OWC technologies, or by hybrid OWC/RF links. In order to establish last mile outdoor interconnection, a free-space optical (FSO) has to be investigated. In this thesis, the performance of all-optical multi-hop scenarios is analyzed under atmospheric conditions. However, nowadays, many end users spend much time in indoor environments where visible light communication (VLC) technology can provide better transmission parameters and, significantly, better coverage. An analytical description of bit error rate for relaying VLC schemes is derived and experimentally verified. Nonetheless, for the last mile, interconnection of a provider and end users (joint outdoor and indoor connection) can be advantageous when combining multiple technologies. Therefore, a hybrid FSO/VLC system is proposed and analyzed for the interconnection of the last mile and last meter bottleneck
Advanced DSP Techniques for High-Capacity and Energy-Efficient Optical Fiber Communications
The rapid proliferation of the Internet has been driving communication networks closer and closer to their limits, while available bandwidth is disappearing due to an ever-increasing network load. Over the past decade, optical fiber communication technology has increased per fiber data rate from 10 Tb/s to exceeding 10 Pb/s. The major explosion came after the maturity of coherent detection and advanced digital signal processing (DSP). DSP has played a critical role in accommodating channel impairments mitigation, enabling advanced modulation formats for spectral efficiency transmission and realizing flexible bandwidth. This book aims to explore novel, advanced DSP techniques to enable multi-Tb/s/channel optical transmission to address pressing bandwidth and power-efficiency demands. It provides state-of-the-art advances and future perspectives of DSP as well
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Linearization techniques to suppress optical nonlinearity
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis is shown the implementation of the linearization techniques such as feedforward and pre-distortion feedback linearization to suppress the optical components nonlinearities caused by the fibre and semiconductor optical amplifier (SOA). The simulation verified these two linearization techniques for single tone direct modulation, two tone indirect modulation and ultra wideband input to the optical fibre. These techniques uses the amplified spontaneously emission (ASE) noise reduction in two loops of SOA by a feed-forward and predistortion linearizer and is shown more than 6dB improvement. Also it investigates linearization for the SOA amplifier to cancel out the third order harmonics or inter-modulation distortion (IMD) or four waves mixing. In this project, more than 20 dB reductions is seen in the spectral re-growth caused by the SOA. Amplifier non-linearity becomes more severe with two strong input channels leading to inter-channel distortion which can completely mask a third adjacent channel. The simulations detailed above were performed utilizing optimum settings for the variable gain, phase and delay components in the error correction loop of the feed forward and Predistortion systems and hence represent the ideal situation of a perfect feed-forward and Predistortion system. Therefore it should be consider that complexity of circuit will increase due to amplitude, phase and delay mismatches in practical design. Also it has describe the compatibility of Software Defined Radio with Hybrid Fibre Radio with simulation model of wired optical networks to be used for future research investigation, based on the star and ring topologies for different modulation schemes, and providing the performance for these configurations
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