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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) - Spectroscopic and Structural Properties of Yb <sup>3+</sup> -Doped and Undoped 2D-Mos <sub/>2</sub> Thin Films for Optoelectronic and Photonic Device Applications
摘要： Molybdenum disulphide (MoS2) has layered structure and is classed as a transition metal-disulphide (TMD) material. Recently it has drawn significant attention for exploring optoelectronic and photonic properties on sub-nanometre scale, with a potential for accessing quantum interactions [1]. The electronic structure and stoichiometry of TMDs make them distinguishable from the metallic graphene, as the TMDs depict a clear bandgap, as in compound semiconductors [2], which is quite attractive for device engineering and applications in photovoltaic, energy storage, and bandgap engineered light-sources [3]. In this research, the fabrication of undoped and Yb3+-ion doped MoS2 nanometre (nm)-scale thin films are discussed using femto-second pulsed laser deposition (fs-PLD) and the structural and spectroscopic properties of fs-PLD are compared with liquid-phase epitaxy grown undoped MoS2 films. Such a comparative analysis may offer materials fabrication platform in future for engineering optoelectronic and photonic devices on silica glass and silicon platforms.
关键词： DFT,Raman spectroscopy,nonlinear optical properties,Molybdenum disulphide,fs-PLD,photonic devices,Yb3+-doped,optoelectronic,thin films
更新于2025-09-19 17:13:59
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Niobium disulfide as a new saturable absorber for an ultrafast fiber laser
摘要： Group VB transition metal dichalcogenides (TMDCs) are emerging two-dimensional materials and have attracted significant interests in the fields of physics, chemistry, and material sciences. However, there are very few reports about the optical characteristics and ultrafast photonic applications based on group VB TMDCs so far. In this work, we have calculated the niobium disulfide (NbS2) band structure by the density functional theory (DFT), which has revealed that NbS2 is a metallic TMDC. In addition, we have prepared an NbS2-microfiber device and the nonlinear optical characteristics have been investigated. The modulation depth, saturation intensity and non-saturable loss have been measured to be 13.7%, 59.93 MW cm?2 and 17.74%, respectively. Based on the nonlinear optical modulation effect, the Er-doped fiber (EDF) laser works in the soliton mode-locking state with the pump power of 94–413 mW. The pulse duration of 709 fs and the maximum average output power of 23.34 mW have been obtained at the pump power of 413 mW. The slope efficiency is as high as 6.79%. Compared to the recently reported studies based on TMDCs comprehensively, our experimental results are better. These experimental results demonstrate that NbS2 with excellent nonlinear optical properties can be used as a promising candidate to advance the development of ultrafast photonics.
关键词： Niobium disulfide,ultrafast fiber laser,saturable absorber,mode-locking,nonlinear optical properties
更新于2025-09-19 17:13:59
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Graphene Photonics || Nonlinear Optical Properties
摘要： In the preceding two chapters, we consider only the linear optical response of graphene; fields of different frequencies do not mix, and the amplitude of the response is linearly proportional to the strength of the excitation optical field. In this chapter, the nonlinear optical response of graphene is discussed. In general, the nonlinear optical response of a material is described by a polarization that is a nonlinear function of the optical field; such a nonlinear polarization is characterized by a nonlinear susceptibility. Because graphene can be treated as a conductor, its nonlinear optical response can alternatively be described by an optical current that is a nonlinear function of the optical field; such a nonlinear current is characterized by a nonlinear conductivity. As in the case discussed in the preceding two chapters for the relation between linear susceptibility and linear conductivity, these two alternative descriptions of nonlinear optical properties of graphene are equivalent. In this section, we first define the nonlinear susceptibility and then make the connection between the nonlinear susceptibility and the nonlinear conductivity.
关键词： Optical Response,Nonlinear Conductivity,Graphene,Nonlinear Optical Properties,Nonlinear Susceptibility
更新于2025-09-16 10:30:52
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Graphene Photonics || Optical Properties
摘要： The linear optical properties of graphene are considered in this chapter. Optoelectronic properties are considered in Chapter 4, and nonlinear optical properties are discussed in Chapter 5. All of these properties are related to the interactions between graphene and an optical field.
关键词： optoelectronic properties,optical properties,graphene,nonlinear optical properties
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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Enhanced Nonlinear Optics Properties of a Bromine Chalcone from a novel Polymorph
摘要： This work presents crystallization, structural elucidation and a thorough study on nonlinear optical (NLO) properties calculated at DFT/CAM-B3LYP/6-311+G(d) level of a new bromine chalcone monoclinic polymorph (BRC-m). Both linear polarizability and second hyperpolarizability associated to NLO process of the intensity dependent refractive index (IDRI) were calculated. The dynamic third-order NLO susceptibility (χ(3)(―ω;ω,ω,―ω)) for BRC-m are higher than obtained experimentally for other chalcone derivatives. Furthermore, the theoretical results for BRC-m were compared with triclinic bromine chalcone (BRC-t); and the change of crystalline state (BRC-t to BRC-m) enhanced the third-order NLO susceptibility from 0.257 × 10―20m2/V2 to 2.48 × 10―20??2/??2 at 1064nm, respectively. This observation shows that future research on crystallization process of known NLO materials is a promising way to improve even more their potential optical application and improve the crystal quality.
关键词： structural elucidation,nonlinear optical properties,bromine chalcone,Crystallization,third-order susceptibility,monoclinic polymorph
更新于2025-09-16 10:30:52
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Nonlinear Optical Properties of Zinc Oxide Thin Films Produced by Pulsed Laser Deposition
摘要： In this work, the nonlinear optical properties of Zinc Oxide (ZnO) thin films produced on microscope slide glass substrates at room temperature (RT) using Pulsed Laser Deposition (PLD) method has been presented. PLD system consists of a vacuum chamber (pumped by a turbo molecular pump, backed with a rotary pump), rotating sample and substrate holders, optical thickness measurement system, infrared temperature measurement system and a nanosecond laser system. Previously deposition vacuum chamber evacuated down to ~10-8 mbar and deposition was taken place about 1.3×10-1 mbar oxygen background gas pressure value. Morphological properties of thin films were obtained by Atomic Force Microscopy (AFM) that shows homogenous and smooth film structure. Thin films crystallinity were investigated by using X-Ray Diffraction (XRD) method and showed that polycrystalline ZnO structure with the largest peak corresponding to (002) orientation but some films contain Zn with (101) orientation . The thicknesses of the films were deduced from reflectance measurement using a fitting software and crosschecked with profilometer and AFM measurements. The thickness of the films ranged between 10 nm and 220 nm. Linear optical properties were obtained by using UV-VIS Spectrometer. Furthermore, we presented the nonlinear optical properties of the ZnO thin films that were obtained by the z-scan method.
关键词： Z-scan system,Zinc Oxide Thin Film,Nonlinear Optical Properties,Pulsed Laser Deposition
更新于2025-09-12 10:27:22
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Quantum-enhanced tunable spin-valley dependent excitonic second harmonic generation in molybdenum disulfide quantum dots
摘要： Developing a robust system with a strong tunable nonlinear second harmonic generation (SHG) is desirable. In this work, we calculate SHG arising from the excitonic states of monolayer molybdenum disulfide quantum dots (MoS2 QDs) with a parabolic confinement potential within massive Dirac fermion model using the density matrix formalism. We theoretically demonstrate that MoS2 QDs can exhibit a giant and tunable Spin-Valley dependent excitonic SHG, which can be tuned from 0 to ～107 pm/V and realized by biasing nanostructured gates or by position-dependent doping. Remarkably, the strength of SHG response is more than two orders of magnitude higher than that in monolayer MoS2. Furthermore, robust excitonic effects together with strong spin-valley coupling in monolayer transition metal dichalcogenides quantum dots (TMDC QDs), which are tunable depending on the strength of the quantum confinement, make them as a promising candidate for ultrathin nonlinear optical materials with large nonlinearities. We believe that this study could spark interest in the nonlinear optical properties of TMDC QDs and open up a variety of new avenues for versatile novel 2D nonlinear photonics and optoelectronic nanodevices.
关键词： second harmonic generation,spin-valley coupling,TMDC QDs,excitonic nonlinear optical properties
更新于2025-09-12 10:27:22
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Applied Surface Science || Synthesis and Nonlinear Optical Studies on Organic Compounds in Laser-Deposited Films
摘要： Organic semiconductors as active materials in thin-film electronic devices such as alkynes, heterocycles, dyes, ferrocenes, spiranes, or porphyrins, with special geometries and certain electronic molecular parameters, which possess nonlinear optical (NLO) properties and offer several major advantages over their inorganic counterparts, are presented in this chapter. There are a number of simple and versatile techniques that can be employed for the deposition of these important classes of materials. The matrix-assisted pulsed laser evaporation (MAPLE) technique provides advantages with regard to making organic films of different morphologies on different types of substrates. New insights into the crystallization growth mechanisms in MAPLE-deposited conjugated polymer films, which realize the connection between the structure and the carrier transport properties, are discussed herein. Second harmonic generation (SHG) capabilities of the thin films were also investigated.
关键词： thin films,organic synthesis,nonlinear optical properties,laser deposition
更新于2025-09-11 14:15:04
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Structural, Spectroscopic, and Excitonic Dynamic Characterization in Atomically Thin Yb <sup>3+</sup> ‐Doped MoS <sub/>2</sub> , Fabricated by Femtosecond Pulsed Laser Deposition
摘要： The large area deposition and synthesis of 10 mm × 10 mm atomically thin Yb3+-doped MoS2 films by femtosecond pulsed laser deposition on a silica glass optical platform for device applications are demonstrated for the first time. The presence of Yb3+-ion doping is confirmed using photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The Yb3+-doped MoS2 films, when excited with a 976 nm laser, exhibit room temperature PL with a peak at 1002 nm. The XPS and Raman spectroscopic analyses of the Yb3+-doped and undoped films show that the deposited films are a mixture of 2H- and 1T-MoS2 after postdeposition annealing at 500 °C. The density functional theory analysis shows that the 1T phase is metastable by +77 kJ (≈0.8 eV) mol-1, when compared with the 2H state at 0 K. Ultrafast transient nonlinear optical spectroscopic measurements prove that the saturable absorption of undoped MoS2 is significantly modified after Yb3+-ion doping, by displaying dopant-host structure charge transfer. The complex transient absorption line shape shows a combination of bleach (negative) signals at the A (670 nm) and B (630 nm) exciton energies, and a strong induced absorption below the A exciton level. The results presented herein provide critical insight in designing novel rare-earth-ion doped 2D materials and devices.
关键词： molybdenum disulfide,femtosecond pulsed laser deposition,saturable absorber,rare-earth ion photoluminescence,nonlinear optical properties
更新于2025-09-11 14:15:04