- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Optical and Thermal Properties of Laser-Ablated Platinum Nanoparticles Graphene Oxide Composite
摘要： Platinum nanoparticles were synthesized in graphene oxide aqueous solution using a laser ablation technique to investigate the effect of optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution. The samples were prepared with different ablation times. The platinum nanoparticles that formed a spherical shape on the surface of graphene oxide solution were authenticated using UV-visible spectrum and transmission electron microscopy patterns. The particle size decreased with increasing ablation time, and the concentration and volume fraction of samples were increased. To obtain the optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution, UV-visible spectroscopy, Z-scan, thermal lens and photoacoustic techniques were used. Consequently, the linear and nonlinear refractive indices increased with an increase in the volume fraction of platinum nanoparticles. It was observed from the spatial self-phase modulation patterns that, the optical nonlinear property of the graphene oxide was enhanced in the presence of platinum nanoparticles, and the nonlinearity increased with an increase in the volume fraction of platinum nanoparticles inside the graphene oxide solution. The thermal diffusivity and thermal effusivity of platinum nanoparticles graphene oxide were measured using a thermal lens and photoacoustic methods, respectively. The thermal diffusivity and thermal effusivity of samples were in the range of 0.0341 × 10?5 m2/s to 0.1223 × 10?5 m2/s and 0.163 W s1/2 cm?2 K?1 to 0.3192 W s1/2 cm?2 K?1, respectively. Consequently, the platinum enhanced the optical and thermal properties of graphene oxide.
关键词： graphene oxide,z-scan,spatial self-phase modulation,Pt-NPs,platinum nanoparticles/graphene oxide composite,laser ablation,photoacoustic,thermal lens
更新于2025-09-16 10:30:52
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High-Efficiency and Broadband Near-Infrared Bi-Functional Metasurface Based on Rotary Different-Size Silicon Nanobricks
摘要： Several novel spin-dependent bi-functional metasurfaces consisting of different-sized rotary silicon nanobricks have been proposed and numerically investigated based on the Pancharatnam–Berry phase and structural phase simultaneously. Here, a transmission mechanism is strictly deduced, which can avoid crosstalk from the multiplexed bi-functional metasurface. Four kinds of high-efficiency including a spin-dependent bi-functional beam deflector, a spin-dependent bi-functional metalens, a bi-functional metasurface with spin-dependent focusing and deflection function, and a spin-dependent bi-functional vortex phase plate. All of the results demonstrate the superior performances of our designed devices. Our work opens up new doors toward building novel spin-dependent bi-functional metasurfaces, and promotes the development of bi-functional devices and spin-controlled photonics.
关键词： metalens,metasurface,phase modulation,vortex beam
更新于2025-09-16 10:30:52
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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) - Realtime Coherent cw THz System: Phase Modulation without Phase Modulator
摘要： In optoelectronic continuous wave (cw) THz spectroscopy phase measurement is very beneficial, to improve SNR and/or to obtain depth information. Often, the required phase modulation limits the acquisition speed and increases the complexity of existing cw THz systems. Commonly, optical free space delay lines, fibre stretchers [1] or electro optical modulators [2] are used for phase modulation. In this paper we demonstrate that a simple optical fiber delay in combination with a fast sweeping laser source can be used for ultrafast fast phase modulation. With this technique we demonstrate a fully fibre-coupled cw THz spectrometer with 58 Hz update rate covering a bandwidth of 2.5 THz. To the best of our knowledge this is the fastest coherent cw THz system demonstrated so far. This makes cw THz systems competitive to time-domain approaches in terms of acquisition speed and simplifies the system architecture significantly. Therefore, it paves the way for compact, broadband and cost-effective THz systems.
关键词： continuous wave,phase modulation,fast sweeping laser,fiber delay,THz spectroscopy
更新于2025-09-16 10:30:52
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Synthesis of bilayer graphene nanosheets by pulsed laser ablation in liquid and observation of its tunable nonlinearity
摘要： Bilayer graphene nanosheets (B-GNSs) have been synthesized from dry-cell graphite electrode by using facile laser ablation in liquid technique in ambient condition. The plasma plume generated on incidence of ns pulsed Nd:YAG laser fundamental radiation of 1064 nm has facilitated the transformation of bulk graphite (BG) into B-GNSs via liquid carbon phase within 30 min of laser irradiation, and the layer number is are found to be increased with further increase in laser ablation time. The thickness dependent coherent nonlinear optical (NLO) response of the synthesized materials in aqueous dispersion has been determined by spatial self-phase modulation technique. The oxygen-containing surface defects in multilayer GNSs (M-GNSs) have led to scarcity in amount of e-h pairs in compared to that in B-GNSs. Therefore, a better NLO polarization has been observed in B-GNSs in compared to that of M-GNSs. Moreover, the thickness dependent thermal conductivity and hydrodynamic performance of GNSs-water dispersion has led to the observation of tunable NLO response with change in temperature as well as with the intensity of pump laser. The experimental findings obtained in this work may be considered as a key step towards fabrication of graphene from graphitic waste materials for development of future nonlinear photonics devices.
关键词： Waste material,Nonlinear optical properties,Optical properties,Spatial self-phase modulation,Laser ablation,Graphene nanosheets
更新于2025-09-16 10:30:52
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Use of heavily doped germanosilicate fibres with a small core diameter in stretchers of ultrashort laser pulses at a wavelength of 1.03 μm
摘要： The use of a heavily doped germanosilicate fibre with a W-profile refractive index and small core diameter in stretchers of ultrashort laser pulses with their subsequent amplification and compression in all-fibre laser systems is considered. The application of fibres of this type makes it possible to stretch, amplify, and then compress a laser pulse with minimum distortions of its initial shape and width. Due to the dispersion properties of these fibres, which allow the pulse duration to be increased significantly at a small fibre length and the third-order positive dispersion of the diffraction-grating-based output compressor to be compensated for, amplified pulses with an energy of 2 mJ and width of 250 fs, free of a picosecond pedestal, are obtained. Several types of fibres intended for the use in stretchers of ultrashort laser pulses are comparatively analysed from the point of view of their dispersion compatibility with a diffraction-grating-based output compressor.
关键词： nonlinear self-phase modulation,fibre lasers,heavily doped germanosilicate fibre,group-velocity dispersion,femtosecond lasers,amplification of ultrashort laser pulses
更新于2025-09-16 10:30:52
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SRS converter – compressor of femtosecond ytterbium laser pulses
摘要： Stimulated Raman scattering (SRS) conversion of femtosecond pulses of an ytterbium laser at a wavelength of 1.03 mm is performed in compressed hydrogen under conditions of nonlinear phase modulation. Temporal compression of frequency-chirped Stokes pulses is carried out, as a result of which 400-fs laser pulses are converted into 27-fs Stokes pulses with a wavelength of 1.8 mm. An average Stokes power of 0.6 W is implemented at an average laser power of 6.3 W and a pulse repetition rate of 20 kHz.
关键词： femtosecond laser,pulse compression,stimulated Raman scattering,nonlinear phase modulation
更新于2025-09-16 10:30:52
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Spectral broadening of a KrF laser via propagation through Xe in the negative nonlinear index regime
摘要： In inertial con?nement (ICF) experiments at the NIKE laser facility, the high-power krypton ?uoride (KrF) laser output beams propagate through long (～75 m) air paths to achieve angular multiplexing, which is required because the KrF medium does not store energy for a suf?ciently long time. Recent experiments and simulations have shown that, via stimulated rotational Raman scattering, this propagation can spectrally broaden the laser beam well beyond the ～1 THz laser linewidth normally achieved by the induced spatial incoherence (ISI) technique used in NIKE. These enhanced bandwidths may be enough to suppress the laser-plasma instabilities which limit the maximum intensity that can be incident on the ICF target. In this paper we investigate an alternative technique that achieves spectral broadening by self-phase modulation in Xe gas, which has a large, negative nonlinear refractive index ～248 nm, and thus completely avoids transverse ?lamentation issues. The collective, nonlinear atomic response to the chaotic, nonsteady state ISI light is modeled using a two-photon vector model, and the effect of near-resonant behavior on the spectral broadening is studied.
关键词： self-phase modulation,laser-plasma instabilities,negative nonlinear index,KrF laser,spectral broadening,Xe gas
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - St. Petersburg, Russia (2019.10.17-2019.10.18)] 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Distortion Analysis of Interferometric Signal with Auxiliary Emission Modulation in Semiconductor Laser
摘要： The results of analysis of distortion of interferometric signal of a semiconductor laser with the current modulation are presented. The mathematical model of the interferometric signal was refined based on experimental data. Measurements were performed for harmonic and triangular auxiliary modulation, and the effect of laser thermal stabilization on the modulation of the interferometric signal was studied.
关键词： phase modulation,external cavity laser,thermal stabilization,distributed feedback laser,distortion of interferometric signal
更新于2025-09-16 10:30:52
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Nonlinear Fiber Optics || Introduction
摘要： This introductory chapter is intended to provide an overview of the fiber characteristics that are important for understanding the nonlinear effects discussed in later chapters. Section 1.1 provides a historical perspective on the progress in the field of fiber optics. Section 1.2 discusses various fiber properties such as optical loss, chromatic dispersion, and birefringence. Particular attention is paid to chromatic dispersion because of its importance in the study of nonlinear effects probed by using ultrashort optical pulses. Section 1.3 introduces various nonlinear effects resulting from the intensity dependence of the refractive index and stimulated inelastic scattering. Among the nonlinear effects that have been studied extensively using optical fibers as a nonlinear medium are self-phase modulation, cross-phase modulation, four-wave mixing, stimulated Raman scattering, and stimulated Brillouin scattering. Each of these effects is considered in detail in separate chapters. Section 1.4 gives an overview of how this book is organized for discussing such a wide variety of nonlinear effects in optical fibers.
关键词： fiber optics,stimulated Raman scattering,four-wave mixing,stimulated Brillouin scattering,chromatic dispersion,nonlinear effects,self-phase modulation,cross-phase modulation,birefringence
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Polarization effects
摘要： A major simplification was made in Section 2.3 while deriving the nonlinear Schr?dinger (NLS) equation. It consisted of assuming that the polarization state of the incident light is preserved during its propagating inside an optical fiber. This is not really the case in practice. In this chapter we focus on the polarization effects and consider the coupling between the two orthogonally polarized components of an optical field induced by the nonlinear phenomenon known as cross-phase modulation (XPM). The XPM is always accompanied with self-phase modulation (SPM) and can also occur between two optical fields of different wavelengths, a situation covered in Chapter 7.
关键词： optical fibers,nonlinear Schr?dinger equation,polarization effects,self-phase modulation,cross-phase modulation
更新于2025-09-12 10:27:22