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Nonlinear Optics || Ultrafast and Intense-Field Nonlinear Optics
摘要： There is currently great interest in the physics of ultrashort laser pulses. Recent advances have led to the generation of laser pulses with durations of the order of 1 attosecond (Hentschel et al., 2001). Ultrashort pulses can be used to probe the properties of matter on extremely short time scales. Within the context of nonlinear optics, ultrashort laser pulses are of interest for at least two separate reasons. The ?rst reason is that the nature of nonlinear optical interactions is often profoundly modi?ed through the use of ultrashort laser pulses, in part because of the broad spectral bandwidth necessarily associated with such pulses. The next two sections of this chapter treat various aspects of the resulting modi?cations of the nature of nonlinear optical interactions. The second reason is that ultrashort laser pulses tend to possess extremely high peak intensities (because laser pulse energies tend to be established by the energy-storage capabilities of laser gain media), and thus short laser pulses tend to have much higher peak powers than longer pulses. The second half of this chapter is devoted to a survey of the sorts of nonlinear optical processes that can be excited by extremely intense laser ?elds.
关键词： attosecond pulses,ultrashort laser pulses,high peak intensities,spectral bandwidth,nonlinear optics
更新于2025-09-23 15:21:01
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Nonlinear Optics || Nonlinear Optics of Plasmonic Systems
摘要： In the present chapter we explore the optical properties of plasmonic systems. The word plasmonics is often associated with the properties of metals. The reason for this association is that both the electrical and optical properties of metals are intimately related to the large number of nearly free electrons present in the conduction band of a metal. In this chapter we will primarily be concerned with the optical properties of metals, although the fundamental results that we obtain equally well describe the optical properties of other types of plasmas. The properties of nearly free electrons have been described earlier in this book, for instance as a limiting case of the Lorentz model described in Section 1.4 and also in terms of relativistic effects of plasmas as described in Section 13.7. The present chapter seeks to describe the properties of plasmonic systems in a cohesive manner. Part of the reason for interest in plasmonic systems is that they display very strong light-matter coupling, and this strong coupling leads to both linear and nonlinear properties that can be qualitatively different from those of nonplasmonic systems. This coupling leads for example to a propagating wave, known as a surface plasmon polariton (SPP), which is a mixed excitation of both electron and electromagnetic ?eld oscillations. Plasmonic systems also tend to display large nonlinear optical effects, both because metals often possess a large value ofχ (3) and because for the case of composite systems electric ?elds tend to become enhanced in regions near a metallic particle. More detailed accounts of the the role of plasmonics in nonlinear optics can be found in the accounts of Kauranen and Zayats (2012), Maier (2007), and Novotny and Hecht (2006a).
关键词： surface plasmon polariton,Drude model,plasmonics,gold,nonlinear optics
更新于2025-09-23 15:21:01
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Chromophores with side isolate groups and applications in improving the poling efficiency of second non-linear optical (NLO) materials
摘要： In this paper, alkyl groups with different lengths are introduced to the two-dimensional spindle-type chromophores as the steric isolators to improve the poling efficiency and long term stability of the poled polymers for second-order nonlinear optical materials. The structure and thermal properties of alkyl functionalized chromophores are characterized by the 1H-NMR, FT-IR, UV-Vis, DSC, TGA, et al. The chromophores with different alkyl groups present extremely similar maximum absorbance wavelength (480nm), which means they have very similar first-order hyperpolarizability. Guest-host polymer doped with chromophores has been prepared. Those materials display different glass transition temperatures and good thermal stability. According to the electro-optic coefficients studies and poling efficiency results, chromophores with longer alkyl side chain groups exhibit better poling efficiency and larger electro-optic coefficients. Especially for the chromophores with octyl group, the poling efficiency increases up to 3 times compared to the reference chromophore 2-(3-{2,5-Phenylmethanol-4-[4-(dimethylamino)styryl]-styryl-5,5-dimethylcyclohex-2-enylidene)malononitrile (STC), while the corresponding electro-optic coefficient of the poled polymers increases up to 4 times, indicating a significant effect of the isolate groups on improving the poling efficiency.
关键词： Chromophores,Electro-optical (EO),Nonlinear optics,Poling efficiency
更新于2025-09-23 15:21:01
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Customizing supercontinuum generation via on-chip adaptive temporal pulse-splitting
摘要： Modern optical systems increasingly rely on complex physical processes that require accessible control to meet target performance characteristics. In particular, advanced light sources, sought for, for example, imaging and metrology, are based on nonlinear optical dynamics whose output properties must often finely match application requirements. However, in these systems, the availability of control parameters (e.g., the optical field shape, as well as propagation medium properties) and the means to adjust them in a versatile manner are usually limited. Moreover, numerically finding the optimal parameter set for such complex dynamics is typically computationally intractable. Here, we use an actively controlled photonic chip to prepare and manipulate patterns of femtosecond optical pulses that give access to an enhanced parameter space in the framework of supercontinuum generation. Taking advantage of machine learning concepts, we exploit this tunable access and experimentally demonstrate the customization of nonlinear interactions for tailoring supercontinuum properties.
关键词： machine learning,optical pulse shaping,supercontinuum generation,photonic chip,nonlinear optics
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA, USA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - Crack-Free Silicon-Nitride-on-Insulator Nonlinear Circuits for Continuum Generation in the C-Band
摘要： We report on the fabrication and testing of silicon-nitride-on-insulator nonlinear photonic circuits for complementary metal–oxide–semiconductor (CMOS) compatible monolithic co-integration with silicon-based optoelectronics. In particular, a process has been developed to fabricate low-loss crack-free Si3N4 730-nm-thick ?lms for Kerr-based nonlinear functions featuring full process compatibility with existing silicon photonics and front-end Si optoelectronics. Experimental evidence shows that 2.1-cm-long nanowires based on such crack-free silicon nitride ?lms are capable of generating a frequency continuum spanning 1515–1575 nm via self-phase modulation. This work paves the way to time-stable power-ef?cient Kerr-based broad-band sources featuring full process compatibility with Si photonic integrated circuits on CMOS lines.
关键词： frequency continuum,photonic integrated circuits (PICs),Complementary metal–oxide–semiconductor (CMOS),nonlinear optics,silicon-nitride-on-insulator (SiNOI)
更新于2025-09-23 15:21:01
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Multi-octave spanning, Watt-level ultrafast mid-infrared source
摘要： We present a source of brilliant mid-infrared radiation, seamlessly covering the wavelength range between 1.33 and 18 μm (7500–555 cm?1) with three channels, employing broadband nonlinear conversion processes driven by the output of a thulium-fiber laser system. The high-average-power femtosecond frontend delivers a 50 MHz train of 250 fs pulses spectrally centered at 1.96 μm. The three parallel channels employ soliton self-compression in a fused-silica fiber, supercontinuum generation in a ZBLAN fiber, and difference-frequency generation in GaSe driven by soliton self-compressed pulses. The total output enables spectral coverage from 1.33 to 2.4 μm, from 2.4 to 5.2 μm, and from 5.2 to 18 μm with 4.5 W, 0.22 W and 0.5 W, respectively. This spatially coherent source with a footprint of less than 4 m2 exceeds the brilliance of 3rd-generation synchrotrons by more than three orders of magnitude over 90% of the bandwidth.
关键词： intra-pulse difference frequency generation (DFG),ultrafast optics,supercontinuum generation,mid-infrared generation,ZBLAN optical fibre,nonlinear optics
更新于2025-09-23 15:19:57
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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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Spina??Controlled Nonlinear Harmonic Generations from Plasmonic Metasurfaces Coupled to Intersubband Transitions
摘要： Metasurfaces that generate nonlinear optical responses provide new degrees of freedom for applications such as nonlinear holography, wave mixing, and new frequencies generation. To extend the utility of flat nonlinear optics, metasurfaces providing both giant nonlinear response for efficient frequency mixing in subwavelength films and a single-beam output with a local wavefront control need to be developed. Metasurfaces with giant nonlinear response have recently been realized using the concept of intersubband polaritons. Separately, nonlinear metasurfaces providing a single-beam nonlinear output with a local wavefront control have been studied. However, a metasurface platform that possesses both of these properties has yet to be demonstrated. Herein, the first such platform is presented and its operation for three- and four-wave mixing processes is demonstrated. This approach is based on using Pancharatnam–Berry phase control of local nonlinear response and on employing meta-atoms with specific symmetries to enable generation of only a single nonlinear beam. Experimentally, 400 nm-thick metasurfaces with a wavefront-controlled single-beam output are demonstrated for second- and third-harmonic generation at pump wavelength of approximately 10 μm. Power conversion efficiencies of 7.6 × 10?4% and 3.6 × 10?4% are obtained for the two nonlinear processes, respectively, at peak pumping intensity of only 80 kW cm?2.
关键词： nonlinear beam-steering,nonlinear optics,spin angular momentum,metasurfaces,intersubband transitions
更新于2025-09-23 15:19:57
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Integrated Raman Laser: A Review of the Last Two Decades
摘要： Important accomplishments concerning an integrated laser source based on stimulated Raman scattering (SRS) have been achieved in the last two decades in the fields of photonics, microphotonics and nanophotonics. In 2005, the first integrated silicon laser based upon SRS was realized in the nonlinear waveguide. This breakthrough promoted an intense research activity addressed to the realization of integrated Raman sources in photonics microstructures, like microcavities and photonics crystals. In 2012, a giant Raman gain in silicon nanocrystals was measured for the first time. Starting from this impressive result, some promising devices have recently been realized combining nanocrystals and microphotonics structures. Of course, the development of integrated Raman sources has been influenced by the trend of photonics towards the nano-world, which started from the nonlinear waveguide, going through microphotonics structures, and finally coming to nanophotonics. Therefore, in this review, the challenges, achievements and perspectives of an integrated laser source based on SRS in the last two decades are reviewed, side by side with the trend towards nanophotonics. The reported results point out promising perspectives for integrated micro- and/or nano-Raman lasers.
关键词： nonlinear waveguide,lasers,microphotonics,nanophotonics,stimulated Raman scattering,optical microcavity,photonics crystals,nonlinear optics,nanocrystals
更新于2025-09-23 15:19:57
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Cuprous Sulfide for Different Laser Pulse Generation: Q-Switching and Mode-Locking
摘要： As a new type of copper-based chalcogenide two-dimensional nanomaterial, cuprous sulfide (Cu2S) has attracted much attention due to its unique band structure and optical properties. In this paper, all-fiber ring laser at the 1.53 μm regime with two kinds of Cu2S saturable absorber devices is demonstrated. The self-started Q-switched pulse with a central wavelength of 1530 nm was obtained for the first time by using Cu2S deposited on the fiber jumper as SA. When the tapered fibers deposited with Cu2S are used to replace the jumpers in the cavity, it can be found that the loss is significantly reduced and a mode-locked pulse with a pulse width of 896 fs has been achieved via evanescent field interaction. This experiment further enriches the application of Cu2S nanosheets in pulsed lasers and promotes the development and application of metal sulfides in nonlinear optics and ultrafast photonics.
关键词： saturable absorber,cuprous sulfide,mode-locking,Q-switching,ultrafast photonics,Cu2S,nonlinear optics
更新于2025-09-23 15:19:57