- 标题
- 摘要
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- 实验方案
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Polarization Modulation Instability in All-Normal Dispersion Microstructured Optical Fibers With Quasi-Continuous Pump
摘要： We report the experimental observation of the polarization modulation instability (PMI) effect in all-normal dispersion (ANDi) microstructured optical ?bers (MOFs) with quasi-continuous pumping. The small unintentional birefringence (～10?5), that any realistic non-polarization maintaining MOF exhibits, contributes to this nonlinear effect. PMI can produce two sidebands whose polarization state is orthogonal to the polarization of the pump. In this work, only one type of PMI process is observed, i.e., when the pump is polarized along the slow axis of the ?ber and sidebands are generated in the fast axis mode. This PMI process was studied experimentally in two ANDi ?bers with different dispersion features and pumped with long (700 ps) pump pulses at 1064 nm. Experimental results are compared with theoretical calculations, with reasonably good agreement.
关键词： Four-wave mixing,Optical polarization.,Microstructured optical ?bers,Chromatic dispersion,Fiber nonlinear optics
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Nonlinear Optics of Multiferroic Materials
摘要： Multiferroics, that is, materials with a coexistence of long-range magnetic and electric order have been attracting tremendous interest because of pronounced coupling effects between magnetic and electric properties that may be the basis for novel devices in which a magnetization is controlled by an electric voltage rather than by energy-intensive electric-current-driven magnetic fields. For monitoring as well as controlling the magnetoelectric coupling, it is essential to have simultaneous access to the magnetic and electric phase of a multiferroic. Only then, the spatial relation between the magnetic and electric domain structures and their response to external perturbations like applied magnetic or electric fields can be studied. Nonlinear optics is particularly well suited for this purpose. The simplest nonlinear optical process is second harmonic generation (SHG) (cid:650) doubling of the frequency of a light wave in a material. SHG is a very symmetry-sensitive process. Any reduction of the symmetry of the frequency-doubling medium can lead to new SHG contributions. Since all types of ferroic order reduce the point group symmetry, SHG can be used as background-free probe of the occurring order. In general, the magnetic and the electric order of a multiferroic change symmetry in different ways so that they are represented by different SHG contributions. These are readily separated by polarization filters so that SHG is an ideal tool to observe the coexistence and correlation between the ferroic phases and their domains in a single experiment. Polarization-dependent SHG spectroscopy and imaging experiments are therefore ideal for analysing the magnetoelectric correlation in a broad variety of multiferroic materials. Some of the most important achievements of nonlinearoptics on multiferroics are: (cid:120) Detection of a coupling between antiferromagnetic and ferroelectric order in hexagonal manganites that occurs in the domain walls rather than in the domains. The result anticipated the current interest in domain walls as functional oxide interfaces [1]. (cid:120) A coupling between magnetic and electric domains in TbMnO3 sustained even across a first-order (cid:120) phase transition [2]. Inversion of a multiferroic domain pattern: The direction of the magnetic or electric order parameter of a multiferroic is reversed across the entire sample, but the domain patterns such is retained [3]. (cid:120) Reversal of a multiferroic domain state without application of external DC fields, just by light [4]. (cid:120) In-situ tracking of the emergence of ferroic order in multiferroic oxide thin films by monitoring the formation of the ordered state by SHG during growth [5]. Optical access in all these experiments involves lasers emitting light pulses of either 100 fs or 5 ns. The laser light can be used to monitor the multiferroic order by nonlinear optics but also, prior to that, to manipulate the ordered state by with an intense pump light beam and analyse the ensuing dynamics. In view of the versatility of the optical access to multiferroics and the generality of the symmetry-based approach to the detection of ferroic phases, it is to be expected that the field of nonlinear optics on multiferroics will continue to develop at the highest speed.
关键词： magnetoelectric coupling,multiferroic materials,second harmonic generation,Nonlinear optics
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Gain-Managed Nonlinear Fiber Amplifier
摘要： We demonstrate a novel pulse evolution in a fiber amplifier. We show that this pulse evolution is driven by a nonlinear attractor and paves the way toward simple, compact fiber systems producing high-energy, ~30-fs pulses.
关键词： Lasers, fiber,Nonlinear optics, fibers,Ultrafast lasers
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Coupling Ideality Optimization of High-Q Deuterated Silicon Nitride Microresonator
摘要： As one of the important photonic integrated platforms, microcavity resonators based on silicon nitride (SiN) have great potential in nonlinear optics applications due to their low loss and high nonlinearity. They are usually designed with a multi-mode structure to achieve high quality factors (Q factors) and small mode volumes, which are beneficial for enhancing light-matter interactions. However, the multi-mode nature also introduces challenges in controlling the coupling between different modes, especially for high-order modes. In this work, we demonstrate a detailed coupling identification of high-Q SiN microresonators with a multi-mode structure. By carefully designing the coupling region between the bus waveguide and the microresonator, we achieve selective excitation of different modes and investigate their coupling characteristics. Our results show that the coupling strength can be effectively controlled by adjusting the gap size and the coupling length, which provides a useful guideline for optimizing the performance of SiN microresonators in nonlinear optics applications.
关键词： microresonator,quality factor,nonlinear optics,silicon nitride,mode coupling
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Threshold Effects and Metastability in Solitary Refractive Index Wells
摘要： Threshold effects and trapping subsequent to the collision of a projectile wave packet and a target are ubiquitous in quantum mechanics. In nonlinear optics, the interaction between a soliton (S) and a dispersive wave (DW) exhibits similarities to wave-packet scattering and offers means for all-optical control [1]. However, threshold effects akin to those in quantum mechanical potential scattering when a bound-state eigenvalue is close to the continuum, and generation of metastable states due to scattering resonances, are not directly allowed. Such phenomena are of high interest in the context of optical technologies concerning storage and manipulation of optical data. Here, we exploit an elaborate yet fabricable nonlinear waveguide [2] to realize an all-optical analogue of a quantum mechanical potential well in terms of the refractive index change induced by a solitary wave. Besides threshold effects this allows for an unexpected trapping mechanism with the ability to engineer metastable states with controllable lifetimes. Observation of the above effects requires S and DW to copropagate at nearly identical group velocities. Our setup features an alternating sequence of regions of normal dispersion (N1?N3) and anomalous dispersion (A1, A2), exhibiting group delay and group velocity dispersion pro?les shown in Figs. 1(a,b). We use numerical simulations of an unidirectional propagation equation for the analytic signal [3]. Firstly, we demonstrate threshold effects in the collision of a “projectile” DW in A2 and a “target” soliton in A1, manifested by peaks in the fraction of transmitted DW energy (Fig. 1(c)) and culminating in its re?ectionless transmission at integer potential strengths νeff de?ned by the DW center frequency (Fig. 1(d)). Off-threshold, interference with re?ected DW components causes a polychotomous wave train (Fig. 1(e)). As evident from the spectrograms in Figs. 1(h,i), inside S, DW exhibits a time-domain structure resembling the quasi bound state closest in νeff. Secondly, we show that a projectile DW launched in N3, colliding with a target soliton in A1, experiences a partial down-shift to a frequency range in A2, group-velocity matched to the soliton. The down-shifted frequency components perceive the soliton as time-domain potential-well to which they are con?ned. Nonzero overlap of the trapped state with the adjacent region of normal dispersion causes its decay, resulting in metastability. Trapping and decay of a metastable state (Figs. 1(f,j)) might also lead to a huge time-delay (Figs. 1(g,k)). We further observe re?ectionless transmission, total (bounce-off) re?ection and trapping in the collision of unequal solitons residing in different regions of anomalous dispersion. Besides the fundamental aspect of providing a quantum analog system, this might pave the way for new applications in optical technologies such as all-optical manipulation of data.
关键词： soliton,solitary refractive index wells,dispersive wave,metastability,nonlinear optics,threshold effects
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Kerr Beam Self-Cleaning in the Telecom Band
摘要： Multimode graded index (GRIN) fibers received a renewed interest in recent years, in particular for the development of new laser sources [1]. In many cases, the use of GRIN fibers is limited by multimodal propagation, leading to a spatially modulated intensity distribution (speckles) at the fiber output. Recent studies have found that quasi-single mode propagation can be recovered in GRIN fibers by the so-called Kerr self-cleaning effect [2]. It consists in the spontaneous recovery of the spatial beam quality, without any frequency shift [2] (as opposed to, e.g., Raman beam self-cleaning [3]). This nonlinear process was only observed so far at laser wavelengths around 1 μm, for peak power levels above a certain threshold value. In this communication, we show that Kerr beam self-cleaning also occurs in a GRIN fiber pumped with chirped pulses in the telecom band (1562 nm). At these wavelengths, the power threshold of the self-cleaning process is decreased by one order of magnitude with respect to pumping at 1 μm.
关键词： GRIN fiber,multimode fibers,nonlinear optics,Kerr beam self-cleaning,telecom band
更新于2025-09-11 14:15:04
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Microcavity-Enhanced Surface Nonlinear Optics
摘要： Confinement and manipulation of photons using microcavities have triggered intense research interest in both fundamental and applied photonics for decades. As a prominent example, whispering-gallery microcavities have ultrahigh Q factors and small mode volumes, making them promising candidates for enhancing light-matter interactions, especially for nonlinear optics. In this work, we report the second-order nonlinear optics induced by symmetry breaking at the surface of an ultrahigh-Q silica microcavity under a sub-milliwatt continuous-wave pump. By dynamically coordinating the double-resonance phase matching, a second harmonic is achieved with a co(cid:81)(cid:89)(cid:72)(cid:85)(cid:86)(cid:76)(cid:82)(cid:81)(cid:3)(cid:72)(cid:73)(cid:73)(cid:76)(cid:70)(cid:76)(cid:72)(cid:81)(cid:70)(cid:92)(cid:3)(cid:82)(cid:73)(cid:3)(cid:19)(cid:17)(cid:19)(cid:23)(cid:28)(cid:8)(cid:3031)(cid:58)-1, 14 orders of magnitude higher than that of the non-enhancement case.
关键词： nonlinear optics,symmetry breaking,microcavity,second harmonic generation,surface
更新于2025-09-11 14:15:04
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Low-threshold 4/5 octave-spanning mid-infrared frequency comb in a LiNbO3 microresonator
摘要： Mid-infrared (MIR) optical frequency combs (OFCs) are ideal light sources for precision metrology and can ?nd extensive applications, especially in molecular spectroscopy and gas detection. Here the generation of mode-locked MIR frequency comb in a LiNbO3 microring through optimized slot-waveguide design is proposed. Such microcomb can span over four-?fths of an octave (ranging from (cid:24)2810 nm to (cid:24)4630 nm) with pump power as low as 50 mW, which can be applied to the 2f -3f self-referencing for fully stabilization and helpful to monolithic integration of the whole system. Further investigations on complex dynamical processes for the microcomb generation suggest that the intracavity soliton drifting caused by the third-order dispersion could be compensated by the self-steepening effect as introducing an additional drift through proper dispersion tailoring. This work could facilitate the low-threshold broadband MIR frequency comb generation technique, as well as provide a way to realize more delicate control of soliton microcombs in both temporal and spectral domain.
关键词： mid-infrared,high-order dispersion,self-steepening,Lithium niobate,nonlinear optics
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Miramar Beach, FL, USA (2019.8.19-2019.8.21)] 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Effects of Spatial Confinement on Nonlinear Light Emission from Plasmonic Nanostructures
摘要： Photoluminescence measurements from spatially confined resonant gap-mode plasmons in a metal-dielectric-metal geometry is performed. The PL signal is nonlinear and broadband in character, and the nonlinear power dependence is seen to deviate from spatially random systems such as rough metal films.
关键词： Plasmons,Nonlinear Optics
更新于2025-09-11 14:15:04
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Nonlinear interactions in multimode optical fibers
摘要： The limitations of single-mode fibers incite multimode fibers to meet the technological demands and explore new physics. Multimode fibers support many spatial modes which can interact with each other through various nonlinear processes and give rise to complex spatiotemporal dynamics. In this review paper, we address intermodal coupling based nonlinear phenomena in short and long pulse regimes. Ultrashort femtosecond pulse regime is dominated by four-wave mixing, self and cross-phase modulation, interpulse as well as intrapulse Raman scattering and provides strong platform for the realization of multitude of nonlinear phenomena such as multimode soliton formation, generation of intense combs of dispersive waves from the multimode soliton, beam clean-up, geometric parametric instability, and optical event horizon. On the other hand, long pulse regime exhibits strong stimulated Raman processes and provides natural tool for the investigation of nonlinear phenomena such as, cascaded Raman scattering, intermodal four-wave mixing based wideband frequency generation, transient grating formation and many others. This article reviews the recent developments in intermodal nonlinear interactions in multimode fiber for both the short and long pulse regimes and provides a roadmap for future research directions in the area of multimode nonlinear fiber optics.
关键词： Intermodal interaction,Multimode fiber,Nonlinear optics
更新于2025-09-11 14:15:04