- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Application of combined optical signal processing methods to compensate for nonlinear effects in fibre-optic communication links
摘要： We report on the use of complex quadrature amplitude signal processing methods based on a combination of static neural networks and special modulation techniques. The conditions are found that allow one to construct the most effective combination of signal processing methods for transmitting signals with considerable power (in the nonlinear regime). Using analytical methods, it is shown how the statistical properties of a signal affect the efficiency of combined processing methods.
关键词： neural networks,nonlinear effects,optical fibre,modulation
更新于2025-09-23 15:22:29
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Sub-200-kHz single soliton generation in a long ring Er-fiber laser with strict polarization control by using twisted fiber
摘要： In the present work we demonstrate a novel single-soliton ultra-low pulse repetition frequency passively mode-locked erbium-doped fiber laser. We mitigate the residual linear birefringence of fiber by fiber twist to achieve a strict control of polarization. For mode-locking the nonlinear polarization rotation (NPR) was used. Special technique was applied to reduce the overdriving of NPR that allows the generation of single soliton in ultra-long cavity. The strict control of polarization yields a stable relation between the polarization state of the pulses propagating in the cavity and the regimes of generation. A 192.12-kHz train of soliton pulses was obtained with pulse duration of 4.7 ps at 1560.1 nm, the average power was 29 μW and the estimated peak power was ? 30.8 W with an energy of 150.9 pJ.
关键词： Ultra-long laser cavity,Solitons,Nonlinear optics,Overdriving nonlinear effects,Mode-locked fiber lasers
更新于2025-09-23 15:19:57
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Design Of A New Thresholder Using For Spiking Photonic Neuron
摘要： In this paper, an ultrafast spiking photonic neuron is illustrated with a new thresholder that based on a loop. The novel all-optical designed thresholder (AOT) is internally passive with unified outside pump source in a highly nonlinear of hollow-core photonic crystal fiber(HC-PCF) loop. It can eliminate noise accumulation and results in robust and efficient information processing and achieves a high extinction ratio in our simulation. This neuron works in a low power state.
关键词： thresholder,nonlinear effects,spiking photonic neuron
更新于2025-09-16 10:30:52
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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 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - THz response of metallic structures to femtosecond laser pulses
摘要： The talk is devoted to the nonlinear effects in metallic structures (like gratings and nanoparticle arrays) irradiated by femtosecond laser pulses. Possible mechanisms of delayed THz response and specific non-quadratic nonlinear regimes of conversion are analyzed. In contrast to previous models, only low-frequency currents inside the metal are considered without involving electron emission and acceleration. Special attention is paid to the role of plasmonic resonances at optical frequency in the enhancement of low-frequency nonlinear response.
关键词： femtosecond laser pulses,plasmonic resonances,metallic structures,nonlinear effects,THz response
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Introduction
摘要： This introductory chapter is intended to provide an overview of the fiber characteristics that are important for understanding the nonlinear effects discussed in later chapters. Section 1.1 provides a historical perspective on the progress in the field of fiber optics. Section 1.2 discusses various fiber properties such as optical loss, chromatic dispersion, and birefringence. Particular attention is paid to chromatic dispersion because of its importance in the study of nonlinear effects probed by using ultrashort optical pulses. Section 1.3 introduces various nonlinear effects resulting from the intensity dependence of the refractive index and stimulated inelastic scattering. Among the nonlinear effects that have been studied extensively using optical fibers as a nonlinear medium are self-phase modulation, cross-phase modulation, four-wave mixing, stimulated Raman scattering, and stimulated Brillouin scattering. Each of these effects is considered in detail in separate chapters. Section 1.4 gives an overview of how this book is organized for discussing such a wide variety of nonlinear effects in optical fibers.
关键词： fiber optics,stimulated Raman scattering,four-wave mixing,stimulated Brillouin scattering,chromatic dispersion,nonlinear effects,self-phase modulation,cross-phase modulation,birefringence
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Self-phase modulation
摘要： The ?rst nonlinear effect that we focus on is the self-phase modulation (SPM), a phenomenon that leads to spectral broadening of optical pulses [1–9]. SPM is the temporal analog of self-focusing of CW beams occurring inside any nonlinear medium with n2 > 0. It was ?rst observed in 1967 in the context of transient self-focusing of optical pulses propagating through a CS2-?lled cell [1]. By 1970, SPM had been observed in solids and glasses by using picosecond pulses. The earliest observation of SPM in optical ?bers was made with a ?ber whose core was ?lled with CS2 liquid [7]. This work led by 1978 to a systematic study of SPM in a silica-core ?ber [9]. This chapter considers SPM as a simple example of the nonlinear effects that can occur inside optical ?bers. Section 4.1 is devoted to the case of pure SPM as it neglects the GVD effects and focuses on spectral changes induced by SPM. The combined effects of GVD and SPM are discussed in Section 4.2 with emphasis on the SPM-induced frequency chirp. Section 4.3 presents two analytic techniques and uses them to solve the NLS equation approximately. Section 4.4 extends the analysis to include the higher-order nonlinear effects such as self-steepening.
关键词： GVD,self-steepening,spectral broadening,optical pulses,frequency chirp,SPM,nonlinear effects,NLS equation,self-phase modulation
更新于2025-09-12 10:27:22
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[Laser Institute of America ILSC? 2019: Proceedings of the International Laser Safety Conference - South Kissimmee, Florida, USA (March 18–21, 2019)] International Laser Safety Conference - Simulated supercontinuum generation in the human eye
摘要： Femtosecond laser pulses of sufficiently high intensity are prone to undergo a number of nonlinear effects while propagating in media. The increasing use of high intensity, femtosecond laser systems underscores the need to understand the retinal hazards generated by nonlinear optical effects, the generation of supercontinuum. Current laser safety standards such as ANSI Z136.1 for pulse wavelengths of 1200 nm - 1400 nm have been determined from experimental studies using pulse durations longer than 100 fs and linear pulse simulations. The combination of strong absorption, broad bandwidth, and dispersive effects makes standard nonlinear pulse simulation methods, based on the slowly varying envelope approximation, unsuitable for the study of near-infrared pulses in biological tissues. To model retinal hazards, we leverage an existing model for linear ultrafast pulse propagation that does not rely on an envelope approximation and simulate spectral broadening in water. Using one-dimensional simulations incorporating the effect of self-focusing, we validate the model using previous experiments for white-light supercontinuum generation in water. We then simulate propagation of 10 fs - 1 ps, 1200 nm - 1400 nm pulses at the current ANSI MPE limit for pulses under 10 ps.
关键词： nonlinear effects,supercontinuum generation,femtosecond laser pulses,self-focusing,ANSI Z136.1,retinal hazards
更新于2025-09-11 14:15:04
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All-optical radio-frequency modulation of Anderson-localized modes
摘要： All-optical modulation of light relies on exploiting intrinsic material nonlinearities [V. R. Almeida et al., Nature 431, 1081 (2004)]. However, this optical control is rather challenging due to the weak dependence of the refractive index and absorption coefficients on the concentration of free carriers in standard semiconductors [R. A. Soref and B. R. Bennett, Proc. SPIE 704, 32 (1987)]. To overcome this limitation, resonant structures with high spatial and spectral confinement are carefully designed to enhance the stored electromagnetic energy, thereby requiring lower excitation power to achieve significant nonlinear effects [K. Nozaki et al., Nat. Photonics 4, 477 (2010)]. Small mode-volume and high-quality (Q)-factor cavities also offer an efficient coherent control of the light field and the targeted optical properties. Here, we report on optical resonances reaching Q ～ 105 induced by disorder on photonic/phononic-crystal waveguides. At relatively low excitation powers (below 1 mW), these cavities exhibit nonlinear effects leading to periodic (up to ～35 MHz) oscillations of their resonant wavelength. Our system represents a test bed to study the interplay between structural complexity and material nonlinearities and their impact on localization phenomena and introduces a different functionality to the toolset of disordered photonics.
关键词： nonlinear effects,disorder-induced cavities,Anderson-localized modes,all-optical modulation,photonic/phononic-crystal waveguides
更新于2025-09-10 09:29:36