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- 摘要
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Spectral Broadening Enhancement in Graphene Integrated Si Waveguides
摘要： Silicon-on-insulator waveguides covered with graphene in length of 60 μm have been fabricated and investigated. Self phase modulation were carried out, and enhanced nonlinear phase shift, Kerr nonlinearity and figure-of-merit have been confirmed in graphene-silicon waveguides by experiments and simulations.
关键词： Integrated optics materials,waveguides,nonlinear optics
更新于2025-09-12 10:27:22
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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) - Coherent Control of the Non-Instantaneous Response of Plasmonic Nanostructes
摘要： Nonlinear metamaterials have revolutionized nonlinear optics, allowing novel abilities that expand the current available nonlinear material capabilities. Due to their unique response, nanoparticles (NP's) have been the subject of research in numerous fields ranging from physics, engineering, biology, medicine and others. Understanding their physical mechanism and properties has enabled unprecedented capabilities in linear and nonlinear optics, sensing, theragnostic biomedical optics, material classifications of molecular structures as complicated as DNA or sensitive as oxygen singlets and much more [1-4]. A complete theoretical description, based on the nonlinear scattering theory, has been found suitable to describe the geometrical contribution of nanostructures (NSs) to their nonlinear response [5]. Yet, until now, a comprehensive theory has been investigated only for the instantaneous nonlinear response. A full response, including the resonant non-instantaneous behavior brought about by their resonant linewidth, has not yet been studied. We experientially demonstrate variance in the nonlinear response by coherently controlling the electric field. We show, for the first time to our knowledge, resonant non-instantaneous properties by coherent control measurements of nonlinear second harmonic generation (SHG) in resonant media. (see Figure 1). In contrary to common perception, we find that transform limited pulses do not yield the strongest nonlinearity in SHG. Approaching strong fields, a decrease in nonlinear behavior is not captures in traditional nonlinear models. We develop a theoretical framework, analogous to a resonant 3 level interaction, capturing non-instantaneous resonant phenomena portraying resonant effects beyond the weak field two-photon description. These include deviations from the conventional SHG nonlinearity which commonly is proportional to the square of the fundamental field intensity (see Figure 2.a). We also show that with changing the localized surface plasmonic resonant wavelength relative to the source's central wavelength, a shift in energy distribution and intensity emerges in the SH process pointing to the relative position of the resonant frequency (see Figure 2.b).
关键词： Nonlinear metamaterials,nanoparticles,second harmonic generation,nonlinear optics,plasmonic nanostructures
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Multimode fibers
摘要： Multimode fibers were first used for nonlinear optics during the 1970s because most optical fibers available at that time supported multiple modes. The situation changed in the 1980s when single-mode fibers were commercialized in view of their telecommunication applications. The interest in multimode fibers re-surfaced after 2005, partly motivated by their use for space-division multiplexing in optical communication systems. As a byproduct of this interest, the nonlinear effects in multimode fibers have been studied extensively since 2010. This chapter covers recent advances in a systematic fashion. Three types of multimode fibers are introduced in Section 14.1, where we also discuss modes supported by them. Section 14.2 extends theory of Section 2.3 to obtain a set of coupled nonlinear equations for various fiber modes. These equations are used in Sections 14.3 to discuss modulation instability and soliton formation in multimode fibers. The focus of Section 14.4 is on the intermodal nonlinear effects that transfer energy among the modes. The spatio-temporal effects are discussed in Section 14.5 with emphasis on spatial beam cleanup and supercontinuum generation through multimode fibers. Section 14.6 is devoted to the nonlinear phenomena in multicore fibers.
关键词： modulation instability,spatio-temporal effects,spatial beam cleanup,soliton formation,multimode fibers,multicore fibers,supercontinuum generation,nonlinear optics,space-division multiplexing,intermodal nonlinear effects
更新于2025-09-12 10:27:22
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Self-starting all-fiber mode-locked laser based on Mamyshev mechanism with high-energy pulse generation at 1550 nm
摘要： An all-fiber mode-locked laser based on Mamyshev mechanism operating at 1550 nm was demonstrated. Self-phase modulation and offset spectral filtering provide high peak-power pulse selection in the laser cavity and induce mode locking. With selected operating parameters, the all-fiber mode-locked laser easily achieves mode locking without external seed pulses or auxiliary starting arms, making the laser convenient to operate. Pulses with maximum energy ~18 nJ and width 230 fs are obtained. Pulse width is almost unchanged with increasing pump power, while pulse energy increases linearly. Starting of the mode-locked laser based on Mamyshev mechanism and output spectra with different pump powers were experimentally investigated.
关键词： Fiber nonlinear optics,Fiber lasers,Laser mode locking,Laser cavity resonators
更新于2025-09-12 10:27:22
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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) - Frequency Comb Generation and Conversion in Non-Centrosymmetric Optical Microresonators
摘要： Optical frequency combs have become the key technology in optical precision measurements [1], bear a high potential for broadband, high-resolution molecular spectroscopy [2] and are promising to advance future optical clocks [3]. For low-power, compact and mobile applications, high-repetition-rate combs such as continuous-wave-pumped Kerr combs [4] and soliton frequency combs based on a third-order nonlinearity [5] have turned out to be especially useful. Thus far, most of these frequency combs operate in the near-infrared (NIR) spectral regime around 1550 nm for reasons such as chromatic material dispersion. Many applications ranging from astronomical spectroscopy, optical clocks and quantum physics all the way to molecular sensing, however, require the frequency combs to be centered in the ultraviolet (UV), visible (VIS) and mid-infrared (MIR) spectral regimes [3,6-8]. In this contribution, we present pathways towards achieving this goal. In a first approach [9], synchronously pumped high-Q whispering gallery-mode resonators with a second-order nonlinearity are employed to convert a high-repetition-rate (21 GHz) NIR comb into the VIS and UV wavelength regimes at the same time (see Fig. 1(a)), using an engineered quasi-phase-matching structure. Furthermore, via degenerate optical parametric oscillation (OPO) the sub-harmonic of the initial comb in the MIR can be generated; non-degenerate OPO even allows for wavelength-tunable signal and idler combs. These results pave the way towards a phase-coherent link of frequency combs across the UV, VIS, NIR and MIR spectral regions in a single microresonator. This could allow for low-power self-referenced frequency combs without the need for octave-spanning spectra (e.g. via 3f-4f-interferometry). Additionally, we show first results towards achieving frequency combs purely based on second-order nonlinearities in few-mode optical microresonators (see Fig. 1(b)). This type of combs not only allows to potentially access wavelength regimes different from the NIR, but they also come with the opportunity to use fast electro-optic tuning, a method that is very weak for Kerr microcombs.
关键词： optical frequency combs,nonlinear optics,microresonators,frequency conversion
更新于2025-09-12 10:27:22
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[IEEE 2019 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Udine, Italy (2019.9.4-2019.9.6)] 2019 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Hybrid Method For Electromagnetic Modelling of Coherent Radiation in Semiconductor Lasers
摘要： In this paper hybrid method for electromagnetic (EM) modelling of coherent radiation in semiconductor lasers is presented. Described approach consist of drift diffusion (DD) model and electromagnetic simulation. Four-level two-electron atomic system with Pauli Exclusion Principle (PEP) extended by electric pumping ratio has been used as lasing model.
关键词： ADE,drift diffusion,PEP,device,FDTD,simulation,nonlinear optics
更新于2025-09-12 10:27:22
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Formation Rules and Dynamics of Photoinduced χ <sup>(2)</sup> Gratings in Silicon Nitride Waveguides
摘要： Silicon nitride has emerged as a prominent platform for building photonics integrated circuits. While its nonlinear properties based on third-order effects have been successfully exploited, an efficient second harmonic generation in standard stoichiometric silicon nitride (Si3N4) waveguides can also be achieved after all-optical poling as was recently shown. The root of such phenomenon has been attributed to the inscription of a self-organized periodic space-charge grating along the waveguide, allowing an effective χ(2) and automatic quasi-phase-matching of pump and second harmonic. However, the different parameters and their role in increasing the efficiency of the process are still not fully comprehended. In this work, we use optical means to identify the general conditions of mode matching occurring during all-optical poling. The overlap integral between pump and second harmonic optical modes is shown to be the governing parameter in determining the features of the χ(2) gratings. Two-photon microscopy measurements of the χ(2) gratings reveal the presence of a secondary periodicity in some of the waveguides used in the study. According to overlap integral simulations such effect can occur due to mode mixing in the waveguide bends. From a study of poling dynamics, we observe that poling efficiency and rate increase as a function of optical pump power and waveguide length. However, in order to initiate poling, a critical pump intensity, which is lower for longer waveguides, must be coupled into waveguide. Temporal and thermal stability tests reveal the nature of charge traps responsible for grating inscription. After applying thermally activated hopping as conductivity mechanism in our samples, we show that only shallow traps seem to be activated during the all-optical poling process.
关键词： stoichiometric silicon nitride,nonlinear optics,all-optical poling,second harmonic generation,quasi-phase-matching
更新于2025-09-12 10:27:22
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Low- and High-Order Nonlinear Optical Characterization of Metal Sulfide Quantum Dots
摘要： Any new synthesized semiconductor nanoparticles or quantum dots (QDs) require to be examined under different conditions using laser pulses of variable energies, wavelengths and durations to understand the nonlinear optical mechanisms and distinguish their attractive properties for practical applications. Among various QDs, the metal sulfides took special attention due to their advanced nonlinear optical properties. Additionally, laser ablation can readily produce plasmas containing QDs that could be used for different applications. One of them is that they can be used as emitters for harmonic generation from ultrashort laser pulses. Here we review recent studies of different low- and high-order optical nonlinearities of metal sulfide QDs, such as optical limiting, two-photon, saturable and reverse saturable types of nonlinear absorption, nonlinear refraction, and generation of high-order harmonics in extreme ultraviolet range.
关键词： metal sulfide quantum dots,nonlinear optics
更新于2025-09-12 10:27:22
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Photobleaching of Submicron DAST Crystals in a PMMA Film by Direct Laser Writing
摘要： Selective photobleaching of DAST (trans-4'-(dimethylamino)-Nmethyl-4-stilbazolium tosylate) non-linear crystals in a 2-μ m-thick polymethacrylate film using direct laser writing at a wavelength of 532 nm at a power of 1–10 mW and a recording speed of 5–35 μ m/s is studied. The laser pattern is established as a function of recording parameters. The destruction of crystals and their transition into the amorphous state enabled one to record a structure that is well resolved in the optical microscope and in the luminescence signal. No layer surface violation at the crystal damage sites is detected. The method ensures the formation of a grating with a periodic modulation of the nonlinearly optical coefficient, which is essential in the quasi-phasematching generation.
关键词： nonlinear optics,DAST,2D grating,photobleaching
更新于2025-09-12 10:27:22
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A computational study of the electronic structure and optical properties of the complex TeO<sub>2</sub>/TeO<sub>3</sub> oxides as advanced materials for nonlinear optics
摘要： Electronic structure of series of tellurium oxide crystals within the TeO2—TeO3 binary system is studied with generalized gradient approximation to DFT, hybrid DFT-HF method with the PBE0 and B3LYP exchange-correlation functionals and with quasiparticle G0W0 approach. Comparison with available experimental data revealed significant underestimation of the band gap values within DFT. The hybrid DFT-HF method leads to slightly overestimated values of the bandgap, and the best agreement with experimental data provides the “one-shot” G0W0 calculations starting from Kohn-Sham solutions. The electronic structure of tellurium oxides is discussed in details. It is found that the bandgap value decreases proportionally to fraction of tellurium atoms in octahedral coordination. This change is due to formation of gap states by 5s(Te) electrons which do not participate in Te(VI)–O bonding. Dielectric susceptibilities are calculated within Random Phase approximation for the series of tellurium oxides and high nonlinear properties of the compounds are predicted by empirical Miller’s rule.
关键词： Ab initio,DFT,tellurium oxides,GW,nonlinear optics,electronic structure
更新于2025-09-12 10:27:22