- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Nonlinear Optics - Novel Results in Theory and Applications || Polarization Properties of the Solitons Generated in the Process of Pulse Breakup in Twisted Fiber Pumped by ns Pulses
摘要： Common optical fibers are randomly birefringent, and solitons formatting and traveling in them are randomly polarized. However, it is desirable to have solitons with a well-defined polarization. With pump relatively long pulses, the nonlinear effects of modulation instability (MI) and stimulated Raman scattering (SRS) are dominant at the initial stage of the process of supercontinuum (SC) generation; modulation instability results in pulse breakup and formation of short pulses that evolve finally to a bunch of solitons and dispersive waves. We do the research of the polarization of solitons formed by the pulse breakup process by the effect of modulation instability with pump pulses of nanoseconds in standard fiber (SMF-28) with circular birefringence introduced by fiber twist, and the twisted fiber mitigates the random linear birefringence. In this work, we found that polarization ellipticity of solitons is distributed randomly; nevertheless, the average polarization ellipticity is closer to the circular than the polarization ellipticity of the input pulse. In the experimental setup. 200 m of SMF-28 fiber twisted by 6 turns/m was used. We used 1 ns pulse to pump the fiber. The results showed that at circular polarization of the input pulse solitons at the fiber output have polarizations close to the circular, while in the fiber without twist, the soliton polarization was random.
关键词： pulse propagation and temporal solitons,birefringence and polarization,fiber optic,stimulated Raman scattering,nonlinear optics
更新于2025-09-19 17:13:59
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Plasmon enhanced second harmonic generation by periodic arrays of triangular nanoholes coupled to quantum emitters
摘要： Optical properties of periodic arrays of nanoholes of a triangular shape with experimentally realizable parameters are examined in both linear and nonlinear regimes. By utilizing a fully vectorial three-dimensional approach based on the nonlinear hydrodynamic Drude model describing metal coupled to Maxwell’s equations and Bloch equations for molecular emitters, we analyze linear transmission, reflection, and nonlinear power spectra. Rigorous numerical calculations demonstrating second and third harmonic generation by the triangular hole arrays are performed. It is shown that both the Coulomb interaction of conduction electrons and the convective term contribute on equal footing to the nonlinear response of metal. It is demonstrated that the energy conversion efficiency in the second harmonic process is the highest when the system is pumped at the localized surface plasmon resonance. When molecular emitters are placed on a surface of the hole array line shapes, the second harmonic signal exhibits three peaks corresponding to second harmonics of the localized surface plasmon mode and upper and lower polaritonic states.
关键词： strong coupling,second harmonic generation,hydrodynamic Drude model,plasmonics,nonlinear optics
更新于2025-09-19 17:13:59
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Near resonant nanosecond laser-driven nonlinear optical response in As <sub/>50</sub> S <sub/>50</sub> thin films
摘要： Nanosecond near resonant excitation in As50S50 thin films leads to strong nonlinear optical response, i.e. nonlinear absorption coefficient up to 4 × 106 cm GW?1 and nonlinear refractive index of 8.5 cm2 GW?1, both of which are the strongest ever reported in amorphous semiconductors. We propose a three-level energy band model to explain this effect, which indicates that the nonlinear process is reverse saturable absorption in nature, mediated by excited-state absorption from slow interband transition between the conduction and valence band. On the other hand, observation of negative nonlinear refractive index reveals the occurrence of self-defocusing effect. Finally, benefitting from the strong nonlinear response, we demonstrate a promising application of As50S50 thin films as an optical limiter for optoelectronic sensors.
关键词： chalcogenide,nonlinear optics,Z-scan,thin films
更新于2025-09-19 17:13:59
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Nonlinear energy deposition of filamentation with femtosecond Airy laser beams in water
摘要： The nonlinear propagation of femtosecond Airy laser ?laments in water is numerically investigated in this paper. We mainly consider the in?uences of con?nement parameter, pulse duration and beam waist on the deposited energy of ?laments. The values of con?nement parameter are found to have a signi?cant impact on the temporal and spatial dynamics of the pulse. The characteristics of energy deposition also di?er widely for Airy beams with di?erent con?nement parameters. The less the con?nement parameter, the more energy deposited by ?lamentation. However, the relative deposited energy evolves relatively small changes under di?erent con?nement parameters. We also found the longer pulse duration and longer beam waist are bene?cial to the total deposited energy increase.
关键词： self-focusing,Airy beams,energy deposition,Ultrafast nonlinear optics
更新于2025-09-19 17:13:59
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[IEEE IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium - Yokohama, Japan (2019.7.28-2019.8.2)] IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium - Characterization of double-bounce scattering in RVoG scenarios using controlled HR-PolTomSAR experiments
摘要： We experimentally investigate mutual information and generalized mutual information for coherent optical transmission systems. The impact of the assumed channel distribution on the achievable rate is investigated for distributions in up to four dimensions. Single channel and wavelength-division multiplexing (WDM) transmission over transmission links with and without inline dispersion compensation are studied. We show that for conventional WDM systems without inline dispersion compensation, a circularly symmetric complex Gaussian distribution is a good approximation of the channel. For other channels, such as with inline dispersion compensation, this is no longer true and gains in the achievable information rate are obtained by considering more sophisticated four-dimensional (4D) distributions. We also show that for nonlinear channels, gains in the achievable information rate can also be achieved by estimating the mean values of the received constellation in four dimensions. The highest gain for such channels is seen for a 4D correlated Gaussian distribution.
关键词： fiber nonlinear optics,optical fiber communication,digital communication,Channel models,mutual Information
更新于2025-09-19 17:13:59
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Alternation of the Mode Synchronization and Desynchronization in Ultrafast Fiber Laser
摘要： Ultrafast fiber lasers offer a unique opportunity to implement optically a Poincaré mapping in the phase space of a variety of complex dissipative dynamical systems operating far from the equilibrium. Understanding of such complex optical dynamical systems revealing, for instance, ultrafast dynamics of the dissipative solitons (DSs) and more complex regimes is important for advancing specification and performance of the mode-locked lasers used in a vast number of applications ranging from spectroscopy and medicine to metrology and telecom. Here, using the mode-locked fiber laser as a test-bed, the Shilnikov-type ultrafast dynamics taking the form of randomly switching between noise-like pulsing and quasi-continuous-wave regimes is experimentally demonstrated. The transient coherence recovery is revealed, during which the noise-like pulse (NLP) is transformed into a coherent DS state and then returned to an incoherent NLP state. The demonstrated alternation of mode synchronization and desynchronization is both of practical importance for developing new types of partially mode-locked lasers and of the fundamental interest for the nonlinear science in the context of revealing routes to the turbulence in distributed nonlinear systems.
关键词： optical spectroscopy,nonlinear optics,fiber laser
更新于2025-09-19 17:13:59
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Resonance Enhancement in Laser-Produced Plasmas (Concepts and Applications) || Front Matter
摘要： The motivation in writing this book is to show the most recent findings of newly emerged field of resonance-enhanced high-order harmonic generation (HHG) using the laser pulses propagating through the narrow and extended laser-produced plasma plumes. It becomes obvious that the developments in this field are aimed for improvement of harmonic yield through precise study of resonance effects during fine-tuning of driving pulses to the resonances. The purpose of writing this book is to acquaint the readers with the most advanced, recently developed methods of plasma harmonics generation at the conditions of coincidence of some harmonics, autoionizing states, and some ionic transitions possessing strong oscillator strengths. This book demonstrates how one can improve the plasma harmonic technique using this approach.
关键词： extreme ultraviolet,plasma harmonics,laser-produced plasmas,high-order harmonic generation,resonance enhancement,XUV,nonlinear optics,HHG
更新于2025-09-19 17:13:59
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Structural, spectroscopic, physical properties and quantum chemical investigation on bromide salt of 4-dimethylaminopyridine NLO material for optoelectronic applications
摘要： In this paper, investigations on the crystal structure, vibrational, physical properties on charge transfer single crystals of 4-dimethylaminopyridinium bromide. Its structural parameters, vibrational, mechanical and optical properties have been studied by SCXRD, FT-IR, FT-Raman, Vickers microhardness test and Ultraviolet-Visible spectral analysis. The computational investigations were carried out to determine the molecular geometries, vibrational modes, HOMO-LUMO analysis, population analysis, MEP, thermodynamics and macroscopic NLO response of the compound. The theoretical and experimental molecular geometrical parameters and vibrational assignments have been in good agreement. Mulliken charge distribution of the present compound was studied systematically. The chemical hardness, electro-negativity and chemical potential of the molecule have been computed by HOMO - LUMO plot. FMO analysis indicates the electron delocalization on the title compound and also its low value of energy gap indicates electron transfer. NLO parameters were calculated by DFT. The calculated hyperpolarizability values showed that the compound is a good candidate for NLO applications.
关键词： Quantum chemical calculation,Single crystals,Nonlinear Optics,Mayer Index,Vibrational spectra
更新于2025-09-19 17:13:59
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Second-harmonic generation from 2D photonic crystal waveguide with simultaneous near-flat dispersions at fundamental frequency and second harmonic
摘要： Photonic crystal waveguides (PCW) have shown great potential to generate second harmonic (SH), but the available schemes with cavity or defect suffer from a lack of multiple wavelengths operation and excessive phase-matching requirement. Here we propose a 2D PCW structure comprised of a modulated single line defect, which is capable of independently controlling the fundamental frequency (FF) and SH modes. Therefore, two near-flat group velocity dispersions can be achieved for these modes, and they simultaneously satisfy phase matching conditions. Based on multiply scattering method, we theoretically demonstrate that the SH resonant modes originated from the nonradiative near-flat dispersion have high quality factors (nearly 6.5 × 104 for the maximum value). And the maximum SH conversion efficiency for these resonant modes are 2 orders of magnitude higher than that of off-resonant modes. In addition, benefitting from the matching of the group velocities of the second harmonic and the fundamental, the central wavelength of SH can be modulated within wavelength range ～3nm. These results can provide potential applications in on-chip integration of photonics and quantum optics.
关键词： Photonic crystal waveguides,Nonlinear optics,Harmonic generation and mixing,Slow light
更新于2025-09-19 17:13:59
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semiconductor waveguide platforms
摘要： We design the high confinement InP/In1?xGaxAsyP1?y semiconductor waveguides and investigate the effective wavelength conversion based on this platform. Efficient confinement and mode field area fluctuation at different wavelength is analyzed to achieve the high nonlinear coefficient. The numerical results show that nearly zero phase-mismatch condition can be satisfied through dispersion tailoring of InP/In1?xGaxAsyP1?y waveguides, and the wavelength conversion ranging over 40 nm with the maximum conversion efficiency ?26.3 dB is achieved. Meanwhile, the influences of the doping parameter y and pumping wavelength on the bandwidth and conversion efficiency are also discussed and optimized. Our demonstration of the excellent all-optical wavelength conversion properties of the InP/In1?xGaxAsyP1?y waveguides could pave the way towards direct integration telecom band devices on stand semiconductor platforms.
关键词： Wavelength conversion,Four-wave mixing,InP/In1?xGaxAsyP1?y waveguide,Nonlinear optics
更新于2025-09-19 17:13:59