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[IEEE 2019 International Topical Meeting on Microwave Photonics (MWP) - Ottawa, ON, Canada (2019.10.7-2019.10.10)] 2019 International Topical Meeting on Microwave Photonics (MWP) - Heterogeneous multicore fiber for optical beamforming
摘要： We experimentally demonstrate, for the first-time to our knowledge, optical beamforming for microwave phased array antennas implemented with a heterogeneous multicore fiber link. The multicore fiber has been engineered to act as an optical sampled true time delay that allows to implement radiofrequency signal processing in a distributed way. It comprises 7 trench-assisted cores where each core is fabricated with different dimensions and core dopant concentration, as to feature a different group delay and chromatic dispersion behavior. We emulated different radio beamsteering scenarios where the beam-pointing angle is modified by tuning the optical wavelength in a 20-nm range, while squint-beam effects are avoided.
关键词： Microwave Photonics,optical beamforming networks,multicore fibers
更新于2025-09-23 15:21:01
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Multicore-fiber solitons and laser-pulse self-compression at light-bullet excitation in the central core of multicore fibers
摘要： The propagation of laser pulses in multicore fibers (MCFs) made of a central core and an even number of cores located in a ring around it is studied. Approximate quasisoliton homogeneous solutions of the wave field in the MCF considered are found. The stability of the in-phase soliton distribution is shown analytically and numerically. At low energies, its wave field is distributed over all MCF cores and has a duration that exceeds the duration of the nonlinear Schr?dinger equation (NSE) soliton with the same energy by many (i.e., five to six) times. In contrast, almost all of the radiation at high energies is concentrated in the central core with a duration similar to the NSE soliton. The transition between the two types of distributions is very sharp and occurs at a critical energy, which is weakly dependent on the number of cores and on the coupling coefficient with the central core. The self-compression mechanism of laser pulses was proposed. It consists in injecting such MCFs with a wave packet being similar to the found soliton and having an energy larger than the critical value. It is shown that the compression ratio depends weakly on the energy and the number of cores and is approximately equal to six times with an energy efficiency of almost 100%. The use of longer laser pulses allows one to increase the compression ratio up to 30–40 times with an energy efficiency of more than 50%. The obtained analytical estimates of the compression ratio and its efficiency are in good agreement with the results of a numerical simulation.
关键词： light-bullet excitation,laser-pulse self-compression,nonlinear Schr?dinger equation,multicore fibers,solitons
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