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- 摘要
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Surface Nonlinear Optics on Centrosymmetric Dirac Nodal‐Line Semimetal ZrSiS
摘要： Gapless surface states (SSs) are features of topological semimetals and are extensively observed. Nowadays, the emerging question is whether the SSs possess exotic and applicable properties. Here, associated with the symmetrical selection rule for nonlinear optical materials, the surface nonlinear optics on a centrosymmetric Dirac nodal-line semimetal ZrSiS crystal is studied and it is found that the SSs bring record nonlinear susceptibilities. The unprecedented conversion efficiencies for second and third harmonic generations are 0.11‰ and 0.43‰, respectively, more than ten orders of magnitude larger than the typical surface second harmonic generation. This work discovers a new route toward studying the SSs for applications in nonlinear photonics.
关键词： density functional theory calculations,ZrSiS,surface states,nonlinear optics,symmetry breaking
更新于2025-09-11 14:15:04
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[IEEE 2018 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Campinas (2018.10.8-2018.10.10)] 2018 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Study of the fabrication of pedestal based-optical waveguides for applications in nonlinear optics
摘要： In this work we present the details regarding the fabrication process of pedestal based optical waveguides, using different materials with large optical nonlinearities as core layer. With the pedestal fabrication process it is possible to use novel materials that are highly inert to chemical etchants or alloys composed of heavy metal elements, since this technique does not require etching of the core material itself. Lateral confinement of light is performed through the fabrication of pedestals by Reactive Ion Etching (RIE) on the lower cladding. The last step in the fabrication process is the deposition of the core layer and, for this reason, etching this layer is no longer necessary. The materials used as core layer are Aluminum Nitride and Titanium oxynitride films, due to the fact that these materials present a great potential for the fabrication of Nonlinear Optics integrated devices.
关键词： nonlinear optics,aluminum nitride,Pedestal waveguide,titanium oxynitride
更新于2025-09-11 14:15:04
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Semi-Nonlinear Nanophotonic Waveguides for Highly Efficient Second-Harmonic Generation
摘要： Quadratic optical parametric processes form the foundation for various applications related to classical and quantum frequency conversion, and have attracted significant interest recently in on-chip implementation. These processes rely on phase matching among the interacting guided modes, and refractive index engineering is a primary approach for this purpose. Unfortunately, modal phase-matching approaches developed so far only produce parametric generation with fairly low efficiencies, due to the intrinsic modal mismatch of spatial symmetries. Here, a universal design and operation principle is proposed for highly efficient optical parametric generation on integrated photonic platforms. By breaking the spatial symmetry of the optical nonlinearity of the device, nonlinear parametric interactions can be dramatically enhanced. This principle is then employed to design and fabricate a heterogeneous titanium oxide/lithium niobate nanophotonic waveguide that is able to offer second-harmonic generation with a theoretical normalized conversion efficiency as high as 2900% W?1 cm?2, which enables the measurement of an experimental efficiency of 650% W?1 cm?2, significantly beyond the reach of conventional modal phase-matching approaches. Unlike nonlinearity domain engineering that is material selective, the proposed operation principle can be flexibly applied to any other on-chip quadratic nonlinear platform, to support ultra-highly efficient optical parametric generation.
关键词： lithium niobate,integrated photonics,nonlinear optics,optical parametric generation
更新于2025-09-11 14:15:04
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Control of THz field waveform emitted from air plasma by chirping two-color laser pulses
摘要： Few-cycle terahertz pulses can be effectively generated in air plasma by mixing an ultrashort laser pulse with its second harmonic. The temporal overlap between these two pulses is critical, which can degrade with the mismatch of group velocities. However, the overlap between the fundamental and second harmonic can be controlled by pre-stretching the temporally separated pulses. In this paper, we study the role of chirp and the relative phase between the fundamental and its second harmonic in the formation of the terahertz waveform. We demonstrate experimentally and explain within the context of transient photocurrent model, that the combination of chirping and relative phase shifting can provide a powerful tool to control the waveform of the terahertz pulse.
关键词： Dispersion,Plasma physics,Nonlinear optics,THz generation,Ultrashort pulses
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Avionics and Vehicle Fiber-Optics and Photonics Conference (AVFOP) - Arlington, VA, USA (2019.11.5-2019.11.6)] 2019 IEEE Avionics and Vehicle Fiber-Optics and Photonics Conference (AVFOP) - Barium Titanate Electro-Optic Modulators
摘要： Barium titanate is a highly desired material for the development of advanced linear phase modulators due to its exceptional electro-optic coefficient, r51, that is over 20 times larger than the largest used in lithium niobate, r33. While the large r51 value in barium titanate has been reported, its utilization in modulators has been limited due to the difficulty in aligning the optical polarization with the crystal axes to maximize the electro-optic effect. Here we discuss the use of off-diagonal electro-optic tensor elements in thin film barium titanate modulators, present recent results, and go into further detail about the challenges and opportunities of using r51 in modulators.
关键词： barium,optical polarization,birefringence,Electrooptic modulators,nonlinear optics,slot waveguide,titanate
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) - Direct Laser Writing Using Chalcogenide Thin Films
摘要： Direct laser writing has been performed in thin AMTIR-1 layers. By using 10 ns laser pulses, 250 nm thick lines have been written by tightly focusing the laser beam on the thin film layers. The possibility to enhance this resolution by using the Sb2Te3 material as super-resolution mask is also discussed.
关键词： saturable absorption,direct laser writing,Z-scan,super-resolution,nonlinear optics,chalcogenide glasses
更新于2025-09-11 14:15:04
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Terahertz Nonlinear Optics of Graphene: From Saturable Absorption to High‐Harmonics Generation
摘要： Graphene has long been predicted to show exceptional nonlinear optical properties, especially in the technologically important terahertz (THz) frequency range. Recent experiments have shown that this atomically thin material indeed exhibits possibly the largest nonlinear coefficients of any material known to date, paving the way for practical graphene-based applications in ultrafast (opto-)electronics operating at THz rates. Here the advances in the booming field of nonlinear THz optics of graphene are reported, and the state-of-the-art understanding of the nature of the nonlinear interaction of graphene with the THz fields based on the thermodynamic model of electron transport in graphene is described. A comparison between different mechanisms of nonlinear interaction of graphene with light fields in THz, infrared, and visible frequency ranges is also provided. Finally, the perspectives for the expected technological applications of graphene based on its extraordinary THz nonlinear properties are summarized. This report covers the evolution of the field of THz nonlinear optics of graphene from the very pioneering to the state-of-the-art works. It also serves as a concise overview of the current understanding of THz nonlinear optics of graphene and as a compact reference for researchers entering the field, as well as for the technology developers.
关键词： terahertz,high-harmonics generation,nonlinear optics,thermodynamic model,graphene
更新于2025-09-11 14:15:04
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Realization of Nonlinear Optical Nonreciprocity on a Few-Photon Level Based on Atoms Strongly Coupled to an Asymmetric Cavity
摘要： Optical nonreciprocity is important in photonic information processing to route the optical signal or prevent the reverse flow of noise. By adopting the strong nonlinearity associated with a few atoms in a strongly coupled cavity QED system and an asymmetric cavity configuration, we experimentally demonstrate the nonreciprocal transmission between two counterpropagating light fields with extremely low power. The transmission of 18% is achieved for the forward light field, and the maximum blocking ratio for the reverse light is 30 dB. Though the transmission of the forward light can be maximized by optimizing the impedance matching of the cavity, it is ultimately limited by the inherent loss of the scheme. This nonreciprocity can even occur on a few-photon level due to the high optical nonlinearity of the system. The working power can be flexibly tuned by changing the effective number of atoms strongly coupled to the cavity. The idea and result can be applied to optical chips as optical diodes by using fiber-based cavity QED systems. Our work opens up new perspectives for realizing optical nonreciprocity on a few-photon level based on the nonlinearities of atoms strongly coupled to an optical cavity.
关键词： optical nonreciprocity,few-photon level,asymmetric cavity,nonlinear optics,cavity QED
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) - Soliton Self-Compression in Hollow Capillary Fibres
摘要： The creation of shorter and shorter optical pulses at higher and higher energies has been one of the primary aims of laser science and nonlinear optics. At high energies (few mJ), the dominant technique is currently the use of self-phase modulation (SPM) and self-steepening in a gas-filled hollow capillary fibre (HCF) to spectrally broaden pump pulses (typically ~30 fs), followed by chirped mirrors to compensate the phase variation across the spectrum and hence achieve pulse compression [1]. In this way high-energy single-cycle pulses are routinely generated. An alternative route to shorter pulses is soliton self-compression, where the dispersion of the fibre is tuned to be anomalous such that it continuously compensates the phase of the pulse as its spectrum expands. This technique is widely established at low power in solid-core optical fibres and at few-μJ energies in hollow-core photonic-crystal fibres (HC-PCF) [2]. Here we experimentally demonstrate soliton self-compression in conventional gas-filled HCF at much higher energy [3]. We will describe how our technique opens the door to generating 1 fs, 1 TW optical pulses.
关键词： optical pulses,nonlinear optics,hollow capillary fibres,soliton self-compression
更新于2025-09-11 14:15:04
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Handbook of Graphene || Hybrid Graphene–Silicon Photonic and Optoelectronic Integrated Devices
摘要： Graphene, a monolayer of carbon atoms arranged in a honeycomb pattern, has many intriguing optical and electrical properties, providing us numerous applications in optoelectronics, nonlinear optics, and biochemical sensing. However, due to the atomic thickness of the material, light–matter interactions in graphene are intrinsically weak, which greatly limit its practical applications. To overcome this challenge, graphene-on-silicon photonic integrated circuits (PICs) have been proposed and demonstrated in recent years. In such PICs, the propagating light in silicon waveguides can strongly interact with the top-layer graphene through in-plane evanescent–field coupling. On the other hand, with unique properties in photonics and optoelectronics, graphene is expected to open a new avenue for the development of revolutionized on-chip applications, which cannot be precedent based on traditional silicon photonic technology. Therefore, this emerging area has attracted a great deal of attention. In this Chapter, we comprehensively introduce theoretical principles, fabrication processes, and applications of graphene-on-silicon PICs, and review recent research progress in this topic.
关键词： silicon photonics,optoelectronics,photonic integrated circuits,optical interconnects,biochemical sensing,Graphene,mid-infrared photonics,nonlinear optics
更新于2025-09-11 14:15:04