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We investigate the plasmon-mediated nonlinear dynamics and the optics of a laser emission of random nanoemitters (NEs) embedded in a two-dimensional (2D) lattice of conducting nanorings (NRs) enhanced by plasmon–polariton (PP) excitations. The interaction of quantum NEs with the PP field in the NRs perturbs the dynamics of the electronic populations in NEs, leading to a significant dependence of laser generation (dynamics) on the plasma frequency ωp of PP. This results in a strong coupling of NE field emission with the PP field and sharp variations of the average current in the NR lattice. The phase transition in the system was found when the macroscopic structures of PP fields are excited simultaneously in different regions of the system if ωp (control parameter) reaches critical value ωc. We have established the analytical dependence of the PP current I = I(ωp/ωc) on the plasma frequency, which is in excellent agreement with the results of numerical simulations. This effect may allow the design of new types of PP active devices with the use of conducting NRs in modern nanoelectronics. [ABSTRACT FROM AUTHOR]

A bipartite system is defined as two microscopic entities being able to exchange energy. When excited by light, the complete optical response functions at first (polarizabilities) and second orders (first hyperpolarizabilities) of such a system are determined using the diagrammatic theory of optics. The generality of the method is ensured by the free choice of light–matter and matter–matter interaction Hamiltonians and by the arbitrary number of quanta involved in the energy exchange. In the dipolar approximation, the optical response functions of the system (i.e., of the interacting entities) are linked to the responses of the interaction-free entities by transfer matrices. These universal matrices identically modify the optical response functions at all orders in the electromagnetic field, allowing the implementation of matter–matter interactions in higher-order processes, such as stimulated or spontaneous Raman scattering and four-wave mixing. This formalism is then applied to various composite systems: dimers, multimers and lattices of nanoparticles and molecules, dense molecular layers, and substrate-induced image dipoles. [ABSTRACT FROM AUTHOR]

Optical metasurfaces, artificial planar nanostructures composed of subwavelength meta-atoms, have attracted significant attention due to their ability to tailor optical nanoscale properties, making them a versatile platform for shaping light in both linear and nonlinear regimes. This paper reports on the realization of second harmonic generation (SHG) enhancement based on a dolmen-type gold metasurface containing two resonances. Nonlinear scattering theory is employed to numerically investigate the SHG enhancement phenomenon in the resonant metasurface. The periodic dolmen-type gold metasurface introduces a diffraction coupling effect between Fano resonance and surface lattice resonance (SLR), providing strong local-field enhancement and significantly enhancing the nonlinear effect. We analyze the influence of the coupling between Fano resonance and SLR on the SHG intensity and achieve a 230-fold enhancement in SHG intensity compared to the single resonance case by adjusting the periodicity of the metasurface. The SHG-enhanced gold metasurface may find applications in sensing, imaging, optical computing, and integrated nonlinear optics. [ABSTRACT FROM AUTHOR]

Second-order nonlinear processes like Sum-Frequency Generation (SFG) are essentially defined in the electric dipolar approximation. However, when dealing with the SFG responses of bulk, big nanoparticles, highly symmetric objects, or chiral species, magnetic and quadrupolar contributions play a significant role in the process too. We extend the diagrammatic theory for linear and nonlinear optics to include these terms for single objects as well as for multipartite systems in interaction. Magnetic and quadrupolar quantities are introduced in the formalism as incoming fields, interaction intermediates, and sources of optical nonlinearity. New response functions and complex nonlinear processes are defined, and their symmetry properties are analyzed. This leads to a focus on several kinds of applications involving nanoscale coupled objects, symmetric molecular systems, and chiral materials, both in line with the existing literature and opening new possibilities for original complex systems. [ABSTRACT FROM AUTHOR]

Optical metamaterials, sensing, nonlinear optics, and surface-enhanced spectroscopies have witnessed the remarkable potential of the anapole mode. While dielectric particles with a high refractive index have garnered significant attention in recent years, the exploration of plasmonic anapole modes with intense localized electric field enhancements in the visible frequency range remains limited. In this study, we present a theoretical investigation on the relationship between the strongest near-field response and magnetic anapole modes, along with their substantial enhancement of Raman signals from probing molecules. These captivating findings arise from the design of a practical metallic oblate spheroid–film plasmonic system that generates magnetic anapole resonances at frequencies within the visible–near-infrared range. This research not only sheds light on the underlying mechanisms in a wide range of plasmon-enhanced spectroscopies but also paves the way for innovative nano-device designs. [ABSTRACT FROM AUTHOR]

Research on novel ultrafast photonic devices with wide adaptability has become important scientific technical means to realize both scheme innovation and performance breakthrough in fiber laser generation. As types of transition metal oxide, manganese dioxide (MnO2) materials exhibit remarkable properties including high photothermal stability, strong oxidation resistance, and excellent optical properties, making them promising candidate for utilization as modulation devices in nonlinear optics and ultrafast optics fields. We investigate the impact of MnO2-based saturable absorber (SA) on the pulse characteristics. The experiment reveals that MnO2-based SA supports effectively pulsed laser generation in wide pump power range and large dispersion parameter space with signal-to-noise ratio more than 85 dB. As far as we know, the pump power response range is outstanding among the most of the reported pulsed lasers, which is attributed to the large modulation depth of MnO2 SA. We also investigate the impact of dispersion on the characteristics of laser output, which is not involved in other similar works. This research indicates that MnO2 as a photonic device has vast potential in advanced ultrafast optics. [ABSTRACT FROM AUTHOR]

Nowadays, people are interested in many nonlinear models in sciences and engineering, e.g., a (2+1)-dimensional generalized nonlinear evolution system in fluid dynamics, plasma physics, nonlinear optics and quantum mechanics. We purpose to study that system by means of constructing one set of the bilinear auto-Bäcklund transformations and one set of the similarity reductions. Our bilinear auto-Bäcklund transformations can link certain solutions for that system with other solutions for that system itself, while our similarity reductions go from that system to a known ordinary differential equation. Our results depend on all the coefficients in that system. The present work could assist the future investigations in fluid dynamics, quantum mechanics, nonlinear optics and plasma physics. [ABSTRACT FROM AUTHOR]

Single crystal synthesis, growth and characterization pose challenges such as impurities, temperature control issues and mechanical stress. The present study aims to address these issues by synthesizing and exploring the physico-chemical properties of a nonlinear semi-organic crystal, tartaric acid and ammonium chloride (TAAC). The crystal growth occurred via the slow evaporation method at ambient temperature using double-deionized water as a solvent. Physico-chemical properties were tested, and characterization included X-ray diffraction, scanning electron microscopy (SEM), and photoluminescence to analyse structure, purity and morphology. Additionally, Fourier-transform infrared spectroscopy, UV-visible spectra and micro hardness methods were employed to analyse the optical properties and determine band-gap energy. Antifungal and antibacterial activities against Candida albicans, Staphylococcus aureus and Pseudomonas aeruginosa were evaluated using the agar-well diffusion method. TAAC demonstrated superior structure and characteristics compared to potassium dihydrogen phosphate crystals across all parameters. [ABSTRACT FROM AUTHOR]

The present work is involved in the synthesize, characterization and evaluating the role of CuO on physical, structural and optical properties of 45P 2 O 5 -(55-x)Na 2 O-xCuO (x = 0, 1.0, 3.0 and 5.0 mol%) compositions. The as-synthesized samples are characterized by various experimental techniques such as XRD, FTIR, Raman and UV visible spectroscopy to study their suitability for laser and non-linear optical applications. The density of glasses increases whereas molar volume decreases from with the doping of CuO in place of Na 2 O. The amorphous nature of the prepared samples is confirmed by X-ray pattern. FTIR and Raman spectra confirm the presence of metaphosphate (Q2) and orthophosphate (Q0) structural units in the prepared glass samples which confirms that the glass network become more polymerised with the addition of CuO in place of Na 2 O. The optical band gap increases from 1.94 to 4.11 eV whereas refractive index decreases from 2.76 to 2.14 with increasing doping of CuO. The molar refraction decreases while metallization criteria increase with CuO doping. This glass material demonstrates promising potential for applications in non-linear optics. [ABSTRACT FROM AUTHOR]

2D transition metal halide oxides (TMHOs) have attracted much interest due to their intriguing ferroelectrics and excellent nonlinear optics, however, their susceptibility to oxidation makes their basic research and practical application a challenge. Therefore, it is crucial to understand the oxidation mechanism and explore effective strategies for protection. Here, taking van der Waals (vdWs) ferroelectric NbOI2 as an example, oxidation mechanisms and tuning the oxidation behaviors of NbOI2 and its heterostructures by a variety of in situ experiments and first‐principles calculations are discovered. The ambient‐pressure X‐ray photoelectron spectra reveal a self‐limiting oxidation in isolated NbOI2, driven by spontaneously formed iodine vacancies that react with oxygen molecules due to their lower formation and adsorption energies. For the heterostructures with a lower Fermi level (such as WSe2) than transition state VI@NbOI2 (NbOI2 rich in I‐vacancies), the charge transfer from NbOI2 to WSe2 drives the continuous and complete oxidation of NbOI2 flakes. Moreover, the heterostructures with a higher Fermi level (such as graphene) than VI@NbOI2 can weaken the oxidation of NbOI2. By linking the energy band structures to oxidation behavior, the work offers a new oxidation mechanism of 2D air‐sensitive materials and a crucial strategy for improving their chemical stability. [ABSTRACT FROM AUTHOR]

The in‐plane anisotropic properties of 2D group IV monochalcogenides offer an additional degree of freedom which can be advantageous in optoelectronic applications. Here, it is demonstrated that the third harmonic generation (THG) produced by ultrathin tin (II) sulfide (SnS) is in‐plane anisotropic with respect to the direction of the excitation linear polarization. The polarization‐resolved THG (P‐THG) measurements are described with a nonlinear optics model, which accounts for the orthorhombic crystal structure of the 2D SnS. The relative magnitudes of the χ(3) tensor components are calculated by recording and simultaneously fitting two orthogonal polarization components of the P‐THG signals. Furthermore, the "THG anisotropy ratio" is introduced, which compares the THG intensity produced when the excitation linear polarization is along the armchair crystallographic direction, with the case when it is along the zigzag direction. The experimental findings provide quantitative information on the anisotropic nature of the THG process in various SnS flakes. Nonlinear anisotropic 2D materials can be used in future optoelectronic devices, where anisotropic polarization sensitivity is required. Having an optical tool that quantitatively probes the effect of the in‐plane anisotropy among different 2D materials, could be of considerable importance for evaluating the performance of such materials and devices. [ABSTRACT FROM AUTHOR]

We demonstrated an inline synthesizer for generating ultrashort pulses in the ultraviolet (UV) range. The inline UV pulse synthesizer comprised three nonlinear crystals located in the propagation path of the fundamental driving laser pulse. Second-harmonic signals with central wavelengths of 420, 375, and 345 nm were generated in turn in the three BBO crystals, resulting in a synthesized UV pulse subsequent to the final nonlinear crystal. Its temporal amplitude and phase could be manipulated easily by changing the relative positions of the crystals, allowing for flexibility of the waveform. The minimum pulse duration of the synthesized UV pulse was 4.7 fs, which was close to the Fourier-transform-limited pulse duration. This ultrashort UV pulse with 19 μ J energy can be utilized in various applications such as high harmonic generation and frustrated tunneling ionization. [ABSTRACT FROM AUTHOR]

In this work, the nonlinear optical (NLO) properties of CuO nanoparticles (CuO NPs) were studied experimentally using the pulsed laser ablation (PLA) technique. A nanosecond Nd: YAG laser was employed as the ablation excitation source to create CuO NPs in distilled water. Various CuO NPs samples were prepared at ablation periods of 20, 30, and 40 min. Utilizing HR-TEM, the structure of the synthesized CuO NPs samples was verified. In addition, a UV–VIS spectrophotometer was used to investigate the linear features of the samples. The Z-scan technique was utilized to explore the NLO properties of CuO NPs samples, including the nonlinear absorption coefficient (β) and nonlinear refractive index ( n 2 ). An experimental study on the NLO features was conducted at a variety of excitation wavelengths (750–850 nm), average excitation powers (0.8–1.2 W), and CuO NPs sample concentrations and sizes. The reverse saturable absorption (RSA) behavior of all CuO NPs samples differed with the excitation wavelength and average excitation power. In addition, the CuO NPs samples demonstrated excellent optical limiters at various excitation wavelengths, with limitations dependent on the size and concentration of CuO NPs. [ABSTRACT FROM AUTHOR]

This research presents the optical limiting properties of a novel axially linked D‐A type compound, LaPc‐C60(OH)n, where lanthanide phthalocyanine serves as the donor and fullerenol as the acceptor. The incorporation of fullerenol expands the π‐conjugated system, decreases the aggregation of the phthalocyanine, and significantly increases the solubility of the compound. The establishment of this D‐A system promotes intramolecular electron transfer, effectively improving both the non‐linear optical (NLO) response and optical limiting properties. In addition, homogeneous poly(methyl methacrylate) (PMMA) composite films (LaPc‐C60(OH)n/PMMA) are prepared using a simple solution casting method. Compared to fullerenol or lanthanum phthalocyanine individually, LaPc‐C60(OH)n exhibited a superior NLO response both in solution and in the solid composite film. In particular, LaPc‐C60(OH)n/PMMA demonstrated an increase in the non‐linear absorption coefficient (2050 cm GW−1) and a larger third‐order magnetization (1.84 × 10−8 esu). In addition to exhibiting an excellent NLO response at 532 nm, LaPc‐C60(OH)n also shows significant NLO enhancement at 1064 nm, extending the limiting range into the near‐infrared region. This behavior is attributed to different nonlinear absorption mechanisms and the synergistic effect that arise from the photo‐induced electron transfer process between the fullerenol and LaPc. [ABSTRACT FROM AUTHOR]

We demonstrate a hybrid nanocomposite combining mesoporous silica, p SiO 2 , as a host medium and guest lithium niobate LiNbO 3 nanocrystals embedded into tubular silica nanochannels by calcination of the precursor mixed solution of lithium and niobium salts. High-resolution transmission electron microscopy, X-ray diffraction and Raman scattering techniques reveal trigonal LiNbO 3 nanocrystals within the p SiO 2 nanochannels, indicating their random texture morphology. Annealing at high temperatures (950 ∘ C) during calcination also leads to partial crystallization of the p SiO 2 matrix with the formation of trigonal α - SiO 2 nanocrystals. The Raman microscopy analysis of the p SiO 2 : LiNbO 3 nanocomposite reveals three structural crystalline phases, α - SiO 2 , LiNbO 3 and a mixed phase which involves the α - SiO 2 phase of host membrane and LiNbO 3 nanocrystals embedded into the membrane. The finite size of the LiNbO 3 nanocrystals results in specific features of the LO-TO phonon frequency splitting, which are investigated by Raman microscopy. In the transmission geometry, the second harmonic generation emission exhibits no Maker fringes and is characterized by a broad angular diagram of diffusely scattered light. The second harmonic generation response is independent of the polarization direction of the incident pump light, thus indicating a spatial isotropy of the nonlinear optical conversion in the p SiO 2 : LiNbO 3 composite, consistent with the randomly oriented textural morphology of the deposited LiNbO 3 nanocrystals. The contribution of the guest LiNbO 3 nanocrystals to the second harmonic generation effect was found to be strongly dominant compared to the partially crystallized host p SiO 2 matrix. The nanocomposite p SiO 2 : LiNbO 3 membrane, set in the 90 ∘ nonlinear optical geometry, shows unusually high diffusely transmitted second harmonic generation light (back-reflected emission), apparently supported by internal light reflection from the tubular nanochannel network. Despite the fundamental interest, the revealed anomalous back-reflected second harmonic generation emission from p SiO 2 : LiNbO 3 nanocomposite membranes expands the prospects for their photonic and nonlinear optical applications. [ABSTRACT FROM AUTHOR]

This paper investigates new analytical wave solutions for the fractional Kuralay-IIB equations (FK-IIBE), including a new definition of the fractional derivative. This model works in disciplines such as ferromagnetic materials, optical fibers, wave mixing, and nonlinear optics. The integrable motion of space curves can be determined by our governing model. This research holds great importance in the area of optical fibers, exact and analytical solitons solution. The polynomial method’s complete discrimination system (CDSPM) is used to identify a variety of exact and analytical soliton solutions such as periodic, hyperbolic, rational, Jacobian elliptic (JE), and trigonometric functions. Additionally, we also convert the JE function into a solitary wave (SW) solution. To provide a comprehensive understanding of the dynamic aspects of the system, we also address bifurcation points, quasi-periodic behavior, sensitivity analysis, Poincarè maps, time series profile, and critical solution conditions. The research offers straightforward, efficient algorithms that can consistently and effectively address FK-IIBE. Machine learning technologies are also utilized to satisfy the criteria defined by dynamic analysis. Python regression learner tools are used for reverse engineering to analyze the mathematical model’s equilibrium based on parameter intervals and thresholds determined by dynamical analysis. [ABSTRACT FROM AUTHOR]

While understanding the competitive adsorption behavior of gas sensor is important, it is yet to be unraveled. Especially for the influence of water molecules to the gas adsorbed on 2D materials. This study explores the potential of layered 2D materials as a candidate material for gas sensing, employing non‐destructive measurement, and second harmonic generation (SHG). The investigation focuses on analyzing oxygen, ammonia, and water vapor adsorbed on a WS2 surface by studying the evolutions in electric dipole and electric field. Leveraging the simplified bond hyperpolarizability model (SBHM), a foundation is established for gas sensors utilizing high‐quality 2D materials. This approach facilitates the detection of material modifications in response to environmental influences, including the inevitable water molecules. The obtained hyperpolarizability from SBHM exhibits remarkable consistency with Langmuir's adsorption model, confirming the physical adsorption in the system. In addition, the competitive effects between gases are explored by comparing experimental results with theoretical predictions based on Boltzmann distribution and density functional theory (DFT) calculations. This highlights the effectiveness of SHG and SBHM in studying gas adsorption on layered van der Waals materials. [ABSTRACT FROM AUTHOR]

The study of conductive oxides has gained momentum within the photonics community due to their unique linear and nonlinear optical properties. Despite recent experiments reporting on high harmonic generation from thin films, the optical/electronic behavior of these compounds at the nanoscale is still not fully understood due to the lack of a suitable theoretical model. In the present work, aluminum zinc oxide is excited near its epsilon‐near‐zero crossing point using incident femtosecond pulses having peak power densities in the 1 TW cm−2 range. A relatively efficient frequency up‐conversion including even and odd harmonics up to the seventh order is observed. A hydrodynamic‐Maxwell theoretical approach is adopted, capable of simultaneously taking into account linear and nonlinear dispersions, nonlocal effects, surface, magnetic, and bulk nonlinearities in a spectral region that spans over two and a half octaves from the UV to the NIR region. The study enables a deeper understanding of the fundamental material parameters regulating optical nonlinearities, providing important insights to engineer this class of materials for applications in sensing, ultra‐fast physics, and spectroscopy. [ABSTRACT FROM AUTHOR]

Ultrafast vortex beams have significant scientific and practical value because of their unique phase properties in both the longitudinal and transverse modes, enabling multi‐dimensional quantum control of light fields. Directly generating watt‐level ultrafast vortex beams with large angular momentum has remained a major challenge due to the limitations of mode‐locked materials and existing spatiotemporal mode‐locking generation methods. In this study, quasi‐2D PEA2(CsPbBr3)n‐1PbBr4 perovskite films are prepared by an anti‐solvent method and employed for the first time in a mode‐locked resonator operating in free space. Utilizing the angle‐based non‐collinear pumping and frequency doubling techniques, the second‐order ultrafast green vortex beams with a power of up to 1.05 W and a duration of 373 ps are generated. Experimental findings demonstrate the strong nonlinear saturable absorption properties of quasi‐2D PEA2(CsPbBr3)n‐1PbBr4 perovskite films at high power levels, highlighting their considerable potential in ultrafast laser technology and nonlinear optics. [ABSTRACT FROM AUTHOR]

Commercial infrared (IR) nonlinear optical (NLO) materials are mainly from chalcopyrite‐type AMQ2 (A = Ag, Zn, M = Ga, Ge, Q = S, Se, P) crystals such as AgGaS2 (AGS), AgGaSe2 (AGSe), and ZnGeP2 (ZGP), in which the basic NLO‐active groups are MQ4 tetrahedral units. However, the small anisotropic character of them critical for small birefringence hinders the practical applications in the available IR wavelength range. In this study, a novel strategy for modulating birefringence is proposed using a cation regulation‐driven compressed hypertetrahedral layer approach and a family of AAg2MS4 (A = Na, K, Rb; M = P, As) IR NLO crystals are successfully obtained. Remarkably, the title compounds increase the birefringence to 0.12–0.15, about three times larger than that of AGS (0.04), while they can maintain large bandgaps and strong NLO effects. In addition, they exhibit congruent‐melting properties, beneficial for bulk single crystal growth. The work offers a firsthand access for designing and fabricating high‐performance IR NLO materials. [ABSTRACT FROM AUTHOR]

2D materials are a promising platform for applications in many fields as they possess a plethora of useful properties that can be further optimized by careful engineering, for example, by defect introduction. While reliable high‐yield defect engineering methods are in demand, most current technologies are expensive, harsh, or non‐deterministic. Optical modification methods offer a cost‐effective and fast mechanism to engineer the properties of 2D materials at any step of the device fabrication process. In this paper, the nonlinear optical responses of mono‐, bi‐, and trilayer molybdenum disulfide (MoS2) flakes are enhanced by deterministic defect‐engineering with a femtosecond laser. A 50‐fold enhancement in the third harmonic generation (THG) and a 3.3‐fold increase in the second harmonic generation (SHG) in the optically modified areas is observed. The enhancement is attributed to resonant SHG and THG processes arising from optically introduced mid‐band gap defect states. These results demonstrate a highly controllable, sub‐micrometer resolution tool for enhancing the nonlinear optical responses in 2D materials, paving the way for prospective future applications in optoelectronics, quantum technologies, and energy solutions. [ABSTRACT FROM AUTHOR]

Lithium niobate and lithium tantalate are among the most widespread materials for nonlinear, integrated photonics. Mixed crystals with arbitrary Nb–Ta ratios provide an additional degree of freedom to not only tune materials properties, such as the birefringence but also leverage the advantages of the singular compounds, for example, by combining the thermal stability of lithium tantalate with the larger nonlinear or piezoelectric constants of lithium niobate. Periodic poling allows to achieve phase-matching independent of waveguide geometry and is, therefore, one of the commonly used methods in integrated nonlinear optics. For mixed crystals, periodic poling has been challenging so far due to the lack of homogeneous, mono-domain crystals, which severely inhibit domain growth and nucleation. In this work, we investigate surface-near (< 1 μ m depth) domain inversion on x-cut lithium niobate tantalate mixed crystals via electric field poling and lithographically structured electrodes. We find that naturally occurring head-to-head or tail-to-tail domain walls in the as-grown crystal inhibit domain inversion at a larger scale. However, periodic poling is possible if the gap size between the poling electrodes is of the same order of magnitude or smaller than the average size of naturally occurring domains. This work provides the basis for the nonlinear optical application of lithium niobate tantalate mixed crystals. [ABSTRACT FROM AUTHOR]

AbstractThe main objective of the study is to analyze the structural behavior and NLO activity of 4-cumyl phenol by experimental and theoretical spectroscopic techniques. Its computational result is compared with the cumene compound. The optimized structural parameters of the title compound were computationally obtained at the B3LYP/6-31G (d, p) basis set. The fundamental modes of vibration were examined by experimental FT-IR, and FT-Raman techniques. The distribution of the vibrational bands was carried out with the help of normal coordinate analysis (NCA). The resulting harmonic wavenumbers were scaled by using NCA method. Topological analysis, such as Electron localization function (ELF), natural bond orbital analysis (NBO), reduced density gradient (RDG) and atoms in molecule (AIM) analysis, molecular electrostatic potential (MEP) have been used to evaluate the intermolecular interaction, especially the hydrogen bonds. UV-visible spectrum of the compound was recorded in the region 200–900 nm and the electronic properties and HOMO-LUMO energies were calculated by time dependent density functional theory approach. [ABSTRACT FROM AUTHOR]

Coherent dispersive wave emission, as an important phenomenon of soliton dynamics, manifests itself in multiple platforms of nonlinear optics from fibre waveguides to integrated photonics. Limited by its resonance nature, efficient generation of coherent dispersive wave with ultra-broad bandwidth has, however, proved difficult to realize. Here, we unveil a new regime of soliton dynamics in which the dispersive wave emission process strongly couples with the splitting dynamics of the driving pulse. High-order dispersion and self-steepening effects, accumulated over soliton self-compression, break the system symmetry, giving rise to high-efficiency generation of coherent dispersive wave in the ultraviolet region. Simultaneously, asymmetric soliton splitting results in the appearance of a temporally-delayed ultrashort pulse with high intensity, overlapping and copropagating with the dispersive wave pulse. Intense cross-phase modulations lead to octave-wide broadening of the dispersive wave spectrum, covering 200–400 nm wavelengths. The highly-coherent, octave-wide ultraviolet spectrum, generated from the simple capillary fibre set-up, is in great demand for time-resolved spectroscopy, ultrafast electron microscopy and frequency metrology applications, and the critical role of the secondary pulse in this process reveals some new opportunities for all-optical control of versatile soliton dynamics. Here the authors propose method for generating octave-spectral-wide ultraviolet pulses in capillary fibres by coupling dispersive-wave radiation with soliton-splitting dynamics, which may trigger advanced applications in ultrafast optics. [ABSTRACT FROM AUTHOR]

A novel design of ultrahigh efficiency and ultralow threshold energy all-optical switches based on local state transition of complete-connected optical waveguide networks (CCOWNs) is proposed. The generation of the ultra-narrow transmission peak and the ultra-strong photonic localization in network is attributed to the mutation of states, which are significant improvements in the performance of all-optical switch. First, the ultra-strong photonic localization induces the Kerr effect in nonlinear material, which transforms the transmission peaks into a transmission valley and results in the super-high efficiency. The efficiency of switch based on CCOWN with 11 unit cell (UC) and each UC possessing 7 nodes was calculated and found to be approximately 1.38 × 10 39 , which is 13 orders of magnitude better than previously reported. Furthermore, the ultra-strong photonic localization also leads to the ultralow threshold energy. Calculations reveal that the threshold control energy of all-optical switch based on CCOWN only with 7 UC and each UC possessing 5 nodes is about 5.78 × 10 - 30 J, which is 5 orders of magnitude smaller than the best reported results. In addition, fitting formulas for the transmission and switching efficiency with UC number have been derived, and the results show that the switching efficiency increased exponentially with the UC number and nodes. This study not only presents a new model for designing all-optical switch with outstanding performance, but also provides the possibility for further practical use of all-optical switch, while deepening our insight into optical waveguide networks. [ABSTRACT FROM AUTHOR]

We report on the observation of the nonlinear optical properties of tungsten disulphide (WS2) in the infrared (IR) region, along with the enhancement in the nonlinearity achieved by integrating gold nanoparticles (AuNPs) in WS2. WS2 was synthesized using liquid phase exfoliation (LPE) and the spray pyrolysis technique, with layers integrated of AuNPs synthesized using de-wetting process. All samples were characterized using FESEM-EDX, AFM, UV-Vis, and Raman Spectroscopy to analyze their properties including their morphology and linear absorption, in addition to band-gap and vibrational analyses. The nonlinear optical (NLO) measurements and analysis were conducted using the Z-scan technique with a 1560 nm femtosecond laser with both on open and closed apertures to determine the nonlinear absorption coefficient (β) and nonlinear refractive index (n2).Samples of WS2 and AuNPs-WS2 were compared for their coefficient values. AuNPs-WS2 obtained higher values of βavg_S1= (2.30 ± 0.06) ×10− 9m/W and βavg_S2= (4.45 ± 0.07) ×10− 9 m/W resulting in a higher nonlinear optical susceptibility of χ (3) = 10.20 × 10− 12 esu, which is double that of WS2-only sample. This enhancement could be significant contribution in optical devices application. [ABSTRACT FROM AUTHOR]

Infrared up‐conversion imaging is used for frequency conversion of near and mid‐infrared photons to the visible or shorter near‐infrared wavelength range where high‐performance silicon sensors can be used for imaging in‐lieu of the cumbersome infrared counterparts. Nonlinear optical crystals are used for up‐conversion imaging, however, this typically requires long lengths, high pump power, and careful phase matching between interacting waves. To miniaturize the up‐conversion imaging device and eliminate stringent phase‐matching requirements, sub‐wavelength size optical metasurfaces are being explored as the nonlinear optical medium supporting resonances in the near‐infrared, albeit being prone to higher‐order diffraction at the up‐converted wavelengths. Here, a novel two‐dimensional (2D) layered material‐based nonlinear optical mirror (NLOM) based wide‐field up‐conversion imaging device is demonstrated with only 45 nm thick Gallium Selenide (GaSe) layer on a gold reflector with a suitable dielectric spacer. Near‐infrared input at 1550 nm is up‐converted to 622 nm visible output in the presence of a pump beam at 1040 nm through a sum frequency generation (SFG) process. The NLOM stack is optimized using particle swarm optimization algorithm for maximizing the detected SFG signal. Image up‐conversion experiments are performed demonstrating real, Fourier‐plane imaging, and real‐time Fourier‐domain processing with good imaging fidelity and efficiency. [ABSTRACT FROM AUTHOR]

The exploration of photon avalanching (PA) luminescence in different lanthanide emitters has profound implications in plentiful frontier applications. However, studies for universal mechanisms at the nanoscale to exhibit giant nonlinear responses in various avalanching emitters are limited. Here, record‐breaking nonlinear responses up to 60th‐order in high‐lying emitting levels of various emitters at room temperature are generated by proposing a universal mechanism named energy relay‐mediated photon avalanche (enrePA). By harnessing energy from the avalanching nano‐engine through the energy relay of Yb3+ ions, the brightness of blue emissions from Tm3+ and Ho3+ can be enhanced with giant optical nonlinearity up to 60th and 38th order, respectively. Further incorporating gadolinium‐based systems, more emitters (Tb3+, Eu3+, Dy3+, Nd3+) can be activated with extreme optical nonlinearities up to 48th‐order. By expanding PA into the full‐spectrum range, the enrePA mechanism opens exciting avenues for flexible and high‐efficiency PA modulation in multilayer nanostructures, enabling the applicability of PA in more technologies such as super‐resolution imaging, lithography, and optical detection. [ABSTRACT FROM AUTHOR]

Raman lasers are an actively developing field of nonlinear optics aiming to create efficient frequency converters and various optical sensors. Due to the growing importance of ultracompact chip‐scale technologies, there is a constant demand for optical device miniaturization; however, the development of a nanoscale Raman laser remains a challenging endeavor. In this work, a fully subwavelength Raman laser operating in visible range is proposed, based on a gallium phosphide nanocylinder resonator supporting a quasi‐bound state in the continuum (quasi‐BIC). The precise spectral matching of the nanoparticle high‐Q modes is performed with the pump and detuned Raman emission wavelengths. The simulations demonstrate an experiment‐ready design of Raman nanolaser with a lasing threshold expected to be as low as Pth≈21mW$P_{\mathrm{th}} \approx 21\nobreakspace \mathrm{mW}$. The proposed configuration represents the prototype of a low‐threshold Raman nanolaser with all dimensions smaller than the operational wavelength. [ABSTRACT FROM AUTHOR]

Pulsed solid‐state lasers comprise 2D materials as saturable absorbers that contain transparent windows of the atmosphere and characteristic fingerprint spectra of several vital molecules that are significant in various applications and research. Over the past few decades, significant progress has been made in the development of narrow pulse width, high energy, high average output power, high efficiency, and simple construction of passively Q‐switched and mode‐locked lasers with 2D materials as saturable absorbers. This review summarizes the development of 2D materials, including graphene, transition metal dichalcogenides, black phosphorus, topological insulators, and MXenes, as modulator devices for solid‐state lasers owing to their broadband operation, excellent nonlinear optical response, low recovery time, ultrafast dynamic processing, and easy fabrication. Then, some new emerging and representative applications of pulsed solid‐state lasers are introduced and illustrated such as laser surgery, material processing, and lidar. Finally, future challenges and perspectives of pulsed solid‐state lasers with 2D materials‐based saturable absorbers are analyzed and addressed. The rapid development of pulsed solid‐state lasers with the continuous improvement of modulation technology is expected to expand opportunities for application in industry, scientific, medical, and other areas. [ABSTRACT FROM AUTHOR]

Two‐dimensional polymers (2DPs) and their layer‐stacked 2D covalent organic frameworks have recently emerged as nonlinear optical (NLO) materials for potential applications in optics. However, the chemistry for designing third‐order NLO 2DP films with large nonlinear absorption coefficient (β) has remained a mystery. Herein, three highly crystalline porphyrin‐integrated 2D polyimines (named as 2DPI‐Zn‐Azo, 2DPI‐2H‐Azo, and 2DPI‐Zn), which are homogeneous films showing large lateral areas over cm2, uniform transparency, and thickness of tens of nanometers are reported. Particularly, the 2DPI‐Zn‐Azo film comprising zinc porphyrin and –NN– displays a large saturable absorption under 532 nm and the highest β (−1.88 × 105 cm GW−1) among the three 2D polyimines, that is also 2–5 orders of magnitude higher than the state‐of‐art performance of photoactive small molecules, porphyrin‐integrated 2DPs, and inorganic 2D materials. Control experiments in combination with theoretical calculation discover that the embedding of metal centers and –NN– results in highly delocalized π‐electrons and narrow bandgap in 2DPI‐Zn‐Azo, which enables fast transfer of the photogenerated electrons after the light‐excited charge separation, thus boosting the NLO performance. This work opens up a new path for the construction of highly efficient third‐order NLO film materials, and pushes the development of 2DPs for optics and optoelectronics. [ABSTRACT FROM AUTHOR]

This study focuses on the investigation of the perturbed Chen–Lee–Liu model with conformable fractional derivative by the implementation of the generalized projective Riccati equations technique. The proposed method uses symbolic computations to provide a dynamic and powerful mathematical tool for addressing the governing model and yielding significant results. Numerous analytical solutions of the governing model, including bell-shaped soliton solutions, anti-kink soliton solutions, periodic solitary wave solutions and other solutions, have been constructed effectively utilizing this effective technique. The findings acquired from the governing model utilizing the suggested technique demonstrate that all results are novel and presented for the first time in this study. Solitons are of immense significance in the domain of nonlinear optics due to their inherent ability to preserve their shape and velocity during propagation. The study of the propagation and the dynamical behaviour of the derived results have been explored by representing them graphically through 3D, density, and contour plots with different selections of arbitrary parameter values. The solitons acquired from the proposed model can provide significant advantages in the field of fiber-optic transmission technology. The obtained results demonstrate that the suggested approach is extremely promising, straightforward, and efficient. Furthermore, this approach may be effectively used in numerous emerging nonlinear models found in the fields of applied sciences and engineering. [ABSTRACT FROM AUTHOR]

We designed novel alkalides such as FLi2-M-OLi3 and FLi2-M-NLi4 (M = Li, Na, K), along with OLi3-M-NLi4 (M = Li, Na) by interacting alkali metal atoms with heterogeneous superalkali clusters in anionic, neutral and cationic configurations. The stability of these superalkali based alkalides are confirmed by its binding energy (Eb). Utilising QTAIM method, the bond strength and nature of bond have been analysed. NPA charge analysis is conducted to forecast charge transfer and also to confirm the alkalide character of the complex along with the electron localisation function (ELF) analysis. The HOMO–LUMO gap analysis is performed to analyse electrical conductivity and chemical reactivity. The nonlinear optical (NLO) properties have been investigated by polarisability and first-order static hyperpolarizibilty (β0), which is found to be as high as 2.77 × 107 a. u. for (OLi3-Li-NLi4)+ complex. The UV-Vis spectra and electronic transitions are used to explain the enhanced NLO responses. The study not only identifies new alkalide candidates but also presents strategies to significantly improve their NLO properties, which may be useful in nonlinear optics and optoelectronics. [ABSTRACT FROM AUTHOR]

We study the nonlinear dynamics of perturbed, spectrally stable T-periodic stationary solutions of the Lugiato–Lefever equation (LLE), a damped nonlinear Schrödinger equation with forcing that arises in nonlinear optics. It is known that for each N ∈ N , such a T-periodic wave train is asymptotically stable against NT-periodic, i.e. subharmonic, perturbations, in the sense that initially nearby data will converge at an exponential rate to a (small) spatial translation of the underlying wave. Unfortunately, in such results both the allowable size of initial perturbations as well as the exponential rates of decay depend on N and, in fact, tend to zero as N → ∞ , leading to a lack of uniformity in the period of the perturbation. In recent work, the authors performed a delicate decomposition of the associated linearized solution operator and obtained linear estimates which are uniform in N. The dynamical description suggested by this uniform linear theory indicates that the corresponding nonlinear iteration can only be closed if one allows for a spatio-temporal phase modulation of the underlying wave. However, such a modulated perturbation is readily seen to satisfy a quasilinear equation, yielding an inherent loss of regularity. We regain regularity by transferring a nonlinear damping estimate, which has recently been obtained for the LLE in the case of localized perturbations to the case of subharmonic perturbations. Thus, we obtain a nonlinear, subharmonic stability result for periodic stationary solutions of the LLE that is uniform in N. This in turn yields an improved nonuniform subharmonic stability result providing an N-independent ball of initial perturbations which eventually exhibit exponential decay at an N-dependent rate. Finally, we argue that our results connect in the limit N → ∞ to previously established stability results against localized perturbations, thereby unifying existing theories. [ABSTRACT FROM AUTHOR]

We propose a nonlinear-optics-based nanosensor to detect malachite green (MG) contaminants on semiconductor interfaces such as silicon (Si). Applying the simplified bond hyperpolarizability model (SBHM), we simplified the second-harmonic generation (SHG) analysis of an MG-Si(111) surface and were able to validate our model by reproducing experimental rotational anisotropy (RA) SHG experiments. For the first time, density functional theory (DFT) calculations using ultrasoft pseudopotentials were implemented to obtain the molecular configuration and bond vector orientation required by the SBHM to investigate and predict the second-harmonic generation contribution for an MG-Si 001 surface. We show that the SBHM model significantly reduces the number of independent components in the nonlinear tensor of the MG-Si(111) interface, opening up the possibility for real-time and non-destructive contaminant detection at the nanoscale. In addition, we derive an explicit formula for the SHG far field, demonstrating its applicability for various input polarization angles. Finally, an RASHG signal can be enhanced through a simulated photonic crystal cavity up to 4000 times for more sensitivity of detection. Our work can stimulate more exploration using nonlinear optical methods to detect and analyze surface-bound contaminants, which is beneficial for environmental monitoring, especially for mitigating pollution from textile dyes, and underscores the role of nonlinear optics in real-time ambient-condition applications. [ABSTRACT FROM AUTHOR]

Silicon nitride is widely used in integrated photonics for optical nonlinear wave mixing due to its low optical losses combined with relatively high nonlinear optical properties and a wide‐range transparency window. It is known that a higher concentration of Si in silicon‐rich nitride (SRN) magnifies both the nonlinear response and optical losses, including nonlinear losses. To address the trade‐off, four‐wave mixing (FWM) is implemented in over a hundred SRN waveguides prepared by plasma‐enhanced chemical vapor deposition in a wide range of SRN refractive indices varying between 2.5 and 3.2 (measured in the C‐band). It is determined that SRN with a refractive index of about 3 maximizes the FWM efficiency for continuous‐wave operation, indicating that the refractive index of SRN is indeed a crucial optimization parameter for nonlinear optics applications. The FWM efficiency is limited by large nonlinear optical losses observed in SRN waveguides with indices larger than 2.7, which are not related to two‐photon absorption. Finally, the third‐order susceptibility χ3$\left(\chi\right)_{3}$ and the nonlinear refractive index n2$n_{2}$ are estimated for multiple SRN refractive indices, and, specifically, the nonlinearities as large as χ3=(12.6±1.4)×10−19 m2 V−2$\left(\chi\right)_{3} = \pm 1.4 \left.\right) \times \left(10\right)^{- 19} \textrm{ } \left(\text{m}\right)^{2} \textrm{ } \left(\text{V}\right)^{- 2}$ and n2=(7.6±0.8)×10−17 m2 W−1$n_{2} = \pm 0.8 \left.\right) \times \left(10\right)^{- 17} \textrm{ } \left(\text{m}\right)^{2} \textrm{ } \left(\text{W}\right)^{- 1}$ are estimated in a waveguide with an SRN refractive index of 3.2. [ABSTRACT FROM AUTHOR]

The optically good quality organic 2-amino 4,6-dimethyl pyrimidine 4-nitrophenol (AMP4N) single crystal (length 120 mm and diameter 15 mm) was grown by immersed Sankaranarayanan–Ramasamy (ISR) method at ambient temperature using methanol as solvent. The ampoule was specially designed for the growth of good quality and bulk size unidirectional single crystal by slow cooling condition. The unwanted temperature gradient developed on the solution surface was completely avoided, hence the formation of secondary nucleation on top of the ampoule is avoided. The growth apparatus and optimization parameters have been made simpler compared to the conventional SR method. Growth direction parallel to the gravity direction can be easily achieved, hence slanted growth could be avoided within the ampoule and also linear transportation of embryos from solution to crystal–solution interface is achieved. The ISR method-grown single crystal was subjected to various characterizations. The structure of AMP4N was confirmed by single-crystal X-ray diffraction analysis. The optical behaviour of the grown crystal was analysed by UV–visible NIR spectrophotometer. Fourier transform infrared spectrum is used to confirm the functional groups present in the AMP4N crystal. The negative photoconductivity nature of the AMP4N single crystal was determined by photoconductivity analysis. The piezoelectric (d33) coefficient has been measured, and the d33 value shows that it is a suitable material for piezoelectric devices. The full-width at half maximum (FWHM) values of various regions indicate that the entire grown crystal has high crystalline perfection and is optically homogeneous. Birefringence interferometry shows that the grown crystal has good refractive index homogeneity. The novel crystal growth ISR method has been reported, and also various studies reveal that the ISR method-grown crystals are favourable for high performance optical device applications. [ABSTRACT FROM AUTHOR]

Photonic crystal fiber is a category of optical fibers, getting great attention by its promise to offer a range of optical characteristics that are not achievable in conventional optical fibers. Engineered dispersion and nonlinear characteristics of photonic crystal fiber (PCF) make it an attractive candidate for nonlinear optics and advanced optical networking in the all-optical domain. An optical network consists of different optical components such as laser sources, amplifiers, regenerators, and convertors for proper signal transmission over long distances. In recent years, the performance of the components has been improving by employing the appealing properties of PCF. The PCF's application on such components is discussed, and the simulated results on gain amplification, regeneration, conversion, fiber laser are reviewed. These developments reveal that the enhanced performance provided by PCF makes it suitable for different optics applications. [ABSTRACT FROM AUTHOR]

We are interested in the existence of normalized solutions to the problem (- Δ) m u + μ | y | 2 m u + λ u = g (u) , x = (y , z) ∈ R K × R N - K , ∫ R N | u | 2 d x = ρ > 0 , in the so-called at least mass critical regime. We utilize recently introduced variational techniques involving the minimization on the L 2 -ball. Moreover, we find also a solution to the related curl–curl problem ∇ × ∇ × U + λ U = f (U) , x ∈ R N , ∫ R N | U | 2 d x = ρ , which arises from the system of Maxwell equations and is of great importance in nonlinear optics. [ABSTRACT FROM AUTHOR]

This paper investigates a generalized form of the nonlinear Schrödinger equation characterized by a logarithmic nonlinearity. The nonlinear Schrödinger equation, a fundamental equation in nonlinear wave theory, is applied across various physical systems including nonlinear optics, Bose–Einstein condensates, and fluid dynamics. We specifically explore a logarithmic variant of the nonlinear Schrödinger equation to model complex wave phenomena that conventional polynomial nonlinearities fail to capture. We derive four distinct forms of the nonlinear Schrödinger equation with logarithmic nonlinearity and provide exact solutions for each, encompassing bright, dark, and kink-type solitons, as well as a range of periodic solitary waves. Analytical techniques are employed to construct bounded and unbounded traveling wave solutions, and the dynamics of these solutions are analyzed through phase portraits of the associated dynamical systems. These findings extend the scope of the nonlinear Schrödinger equation to more accurately describe wave behaviors in complex media and open avenues for future research into non-standard nonlinear wave equations. [ABSTRACT FROM AUTHOR]

Of late, it has been recognized that both the band gap and carrier mobility play crucial roles in the linear/nonlinear optical applications of nanolayered two-dimensional van der Waals (vdW) transition-metal disulfide compounds. Due to their unique anisotropic physics and twisted octahedral structure, MoSe2 nanofilms have emerged as a focal point of research. This study focuses on the growth of MoSe2 nanofilms via magnetron sputtering on various third-generation semiconductor nanofilms (AGZ: AlN, Ga2O3, and ZnO). The resulting nanocomposite films exhibit remarkably fast carrier dynamics. Morphological analysis using scanning electron microscopy (SEM) and finite-difference time-domain (FDTD) simulation confirmed the structural characteristics and revealed significant changes in electric, magnetic, and polarization fields within the nanoheterojunction films upon stress application. Moreover, these findings highlight evident light-matter interaction and efficient carrier transport. In addition, the linear and nonlinear optical absorption characteristics of MoSe2/AGZ were investigated along with the dynamic processes of charge separation, transfer, and energy transfer at the interface of the heterojunction. Furthermore, an energy-level model for the charge transition process under light irradiation was established. The nonlinear absorption coefficient (NLA) of MoSe2 nanoheterojunctions is in the range of 10–2 to 10–3 cm/W, which is 10 to 100 times higher than that of pure material. Additionally, by evaluating the figure-of-merit (FOM) performance index for MoSe2 nanoheterojunctions, we discovered that its ultrafast NLA behavior can be utilized in devices such as all-optical switches. This provides a theoretical foundation for the fabrication of functional heterojunctions. [ABSTRACT FROM AUTHOR]

Designing and synthesizing multifunctional hybrid copper halides with near ultraviolet (NUV) light‐excited high‐energy emission (<500 nm) remains challenging. Here, a pair of broadband‐excited high‐energy emitting isomers, namely, α‐/β‐(MePh3P)2CuI3 (MePh3P=methyltriphenylphosphonium), were synthesized. α‐(MePh3P)2CuI3 with blue emission peaking at 475 nm is firstly discovered wherein its structure contains regular [CuI3]2− triangles and crystallizes in centrosymmetric space group P21/c. While β‐(MePh3P)2CuI3 featuring distorted [CuI3]2− planar triangles shows inversion symmetry breaking and crystallizes in the noncentrosymmetric space group P21, which exhibits cyan emission peaking at 495 nm with prominent near‐unity photoluminescence quantum yield and the excitation band ranging from 200 to 450 nm. Intriguingly, β‐(MePh3P)2CuI3 exhibits phase‐matchable second‐harmonic generation response of 0.54×KDP and a suitable birefringence of 0.06@1064 nm. Furthermore, β‐(MePh3P)2CuI3 also can be excited by X‐ray radioluminescence with a high scintillation light yield of 16193 photon/MeV and an ultra‐low detection limit of 47.97 nGy/s, which is only 0.87 % of the standard medical diagnosis (5.5 μGy/s). This work not only promotes the development of solid‐state lighting, laser frequency conversion and X‐ray imaging, but also provides a reference for constructing multifunctional hybrid metal halides. [ABSTRACT FROM AUTHOR]

This study presents the design, synthesis, and comprehensive characterization of a novel series of D‐π‐A type malononitrile‐derived chromophores, BTC‐1–BTC‐4. Combining various spectroscopic techniques, nonlinear Z‐scan measurements, and quantum chemical calculations, we revealed the intricate relationship between nonlinear optical properties and the interplay of molecular structure, intramolecular charge transfer (ICT), and dipole moments (μ). Our experimental and computational findings corroborate that the polarization degree in the ground state, the charge separation in the excited state and twisted intramolecular charge transfer (TICT) collectively dictate the nonlinear optical properties of the compounds. Notably, BTC‐1 exhibits an exceptional nonlinear absorption coefficient β value (2×10−8 m W−1), attributed to its optimized charge transfer efficiency and pronounced degree of charge separation. Our findings provide actionable insights for the rational design of high‐performance organic Nonlinear optics (NLO) materials with potential applications in advanced photonic devices. [ABSTRACT FROM AUTHOR]

Layered ternary type‐II Weyl semimetals demonstrate promising applications in high‐performance and broadband optoelectronics, therefore it is crucial to gain insights into their photocarriers’ dynamics. In this work, the probing polarization dependence of non‐equilibrium dynamics in NbIrTe4 is investigated by using transient reflectivity spectroscopy. Following photoexcitation at 3.18 eV, the dynamical response of 1.59 eV probe pulse exhibits a strong dependence on probe polarization. The relaxation comprises two components: a rapid recovery of ≈0.6 ps attributed to the electron–phonon scattering, and an anomalous slow recovery spanning hundreds of picoseconds attributed to the photoinduced quasi‐particle. The polarization dependence of rapid relaxation time τ is indicative of the in‐plane anisotropy of electron–phonon coupling in NbIrTe4. The slow relaxation modulated by a latest reported 16 cm−1 coherent phonon also shows strong probing polarization dependence, further revealing the anisotropic nature of electron–phonon coupling and the possibility of anisotropic lattice distortion, as well as photoinduced polaron, under ultrafast photoexcitation in NbIrTe4. The dynamical anisotropy in NbIrTe4 has provided valuable guidance for the application of NbIrTe4 in polarization‐sensitive nonlinear optics or optoelectronic devices and offers insights into the unique carrier transport as well as phonon transport properties of this newly established topological material. [ABSTRACT FROM AUTHOR]

Silicon nitride (Si3N4) photonic integrated circuits are rapidly developing in recent decades. The low loss of Si3N4 attracts significant attention and facilitates a wide range of applications in integrated photonics. In this work, we demonstrate the foundry fabrication of a 300-nm-thick 8-in. wafer-scale Si3N4 platform, with a microresonator intrinsic quality factor of up to 15 × 10 6 , corresponding to an ultralow loss of 2.2 dB/m. Leveraging this platform, we develop a mature process design kit, achieving a single-mode waveguide propagation loss of less than 5 dB/m, an edge coupler loss of 1.3 dB, and an insertion loss of 0.07 dB for multimode interference couplers. Utilizing the processed Si3N4 chip, we realize a hybrid integrated tunable external cavity laser with a tuning range from 1534 to 1602 nm, a record-high side-mode suppression ratio of up to 76 dB, an optical power of 26 mW, and an intrinsic linewidth of down to 314 Hz. Our work lays a solid foundation for the further development of applications, including nonlinear optics, quantum optics, optical communications, and ranging. [ABSTRACT FROM AUTHOR]

In this study, we aimed to obtain optical soliton solutions of the perturbed Fokas–Lenells equation having the parabolic law of self-phase modulation in the presence of spatio-temporal dispersion. The Fokas–Lenells equation is significant in nonlinear optics, particularly for modeling femto-second pulse propagation. By implementing the enhanced Kudryashov method, we derive dark, bright, and kink optical solitons for the investigated model. Visualizing the obtained results supported by 3D and 2D simulations and examining the effects of the parameters within the model on the soliton behavior constitute the other branches of the study. Considering that the interaction of various self-phase modulation forms with the chromatic dispersion term is different and its effects on soliton behavior are different, the parabolic law nonlinearity form is examined in the study and the results obtained are aimed at contributing to studies on both the model and nonlinear optics. [ABSTRACT FROM AUTHOR]

[Display omitted] Inversion symmetry broken 3R phase transition metal dichalcogenides (TMDs) show fascinating prospects in spintronics, valleytronics, and nonlinear optics. However, the controlled synthesis of 3R phase TMDs is still a great challenge. In this work, two-dimensional 3R-NbSe 2 single crystals up to 0.2 mm were synthesized for the first time through chemical vapor deposition method by designing a space-confined system. The crystal size and morphology can be controlled by the location of the stacked substrates and the amount of the Nb 2 O 5 precursor. Scanning transmission electron microscopy and Raman measurements reveal the NbSe 2 exhibits a pure 3R stacking mode with relatively weak interlayer van der Waals interactions. Importantly, 3R-NbSe 2 shows obvious second harmonic generation signal which intensity intensified as thickness increases. Density functional theory calculations and optical absorption demonstrate the coexistence of metallic and semiconducting optical properties of 3R-NbSe 2. We designed a NbSe 2 /WS 2 /NbSe 2 photodetector utilizing the metallicity of 3R-NbSe 2 , which shows good performance especially an ultrafast response (6–7 μs, 0.5 ms − 7.9 s for Au electrodes in literature). The proposed strategy and findings are of great significance for the growth of many other 3R-TMDs and applications of nonlinear optical and ultrafast devices. [ABSTRACT FROM AUTHOR]

Flexible or wearable devices are of great interests in the modern technologies, and oxide thin films are critical components for such applications. In this work, epitaxial LiNbO 3 (LNO) thin film integrated on flexible mica substrate has been achieved. Al-doped ZnO (AZO) layer has been first deposited as buffer layer to obtain the epitaxial LNO film, furthermore AZO serves as bottom electrode for electrical measurement. The as-deposited LNO film exhibits high epitaxial quality with c-direction growth. The transmittance measurement indicates the high transparency of the film, ～85 % in visible range and ～90 % in near infrared region up to 1500 nm. The second harmonic generation (SHG) measurement confirms the nonlinearity of the flexible LNO film. The LNO/AZO/mica film also presents apparent ferroelectric response. Overall, the high-quality LNO integrated on flexible mica could be potentially applied in wearable optical and electrical devices. [ABSTRACT FROM AUTHOR]

The “field tensor” is the tensor product of the electric fields of the interacting waves during a sum‐ or difference‐frequency generation nonlinear optical interaction. It is therefore a tensor describing light interacting with matter, the latter being characterized by the “electric susceptibility tensor.” The contracted product of these two tensors of equal rank gives the light‐matter interaction energy, whether or not propagation occurs. This notion having been explicitly or implicitly present from the early pioneering studies in nonlinear optics, its practical use has led to original developments in many highly topical theoretical or experimental situations, at the microscopic as well macroscopic level throughout a variety of coherent or non‐coherent processes. The aim of this review article is to rigorously explain the field tensor formalism in the context of tensor algebra and nonlinear optics in terms of a general time‐space multi‐convolutional development, using spherical tensors, with components expressed in the frame of a common basis set of irreducible tensors, or Cartesian tensors. A wide variety of media are considered, including biological tissues and their imaging, artificially engineered by various combinations of optical and static electric fields, with the two extremes of all‐optical and purely electric poling, and also bulk single crystals. [ABSTRACT FROM AUTHOR]

Highly efficient off‐diagonal THz generators based on novel organic nonlinear optical single crystals with optimal polar axis orientation in the as‐grown crystal morphology are introduced. The newly developed fluorinated and non‐fluorinated cationic chromophores exhibit a non‐centrosymmetric crystal structure with P21 space group symmetry in the crystalline phase. In particular, PB5FB‐T (5‐fluoro‐2‐(4‐(2‐(hydroxymethyl)pyrrolidin‐1‐yl)styryl)‐3‐methylbenzothiazol‐3‐ium 4‐methylbenzenesulfonate) crystals have an in‐plane polar axis, along with a top‐level off‐diagonal component of the nonresonant effective first hyperpolarizability of ≈100 × 10−30 esu. This stands in stark contrast to previously reported organic THz crystals, which either show a small off‐diagonal optical nonlinearity with an in‐plane polar axis or a large off‐diagonal optical nonlinearity with an almost out‐of‐plane polar axis. Employing an off‐diagonal THz generation configuration, PB5FB‐T crystals generate a THz electric field approximately four times higher than previously reported benchmark analogous crystals with a polar axis nearly out‐of‐plane. Moreover, PB5FB‐T crystals yield smooth THz spectral shapes without significant absorption dimples up to 6 THz when utilizing 130‐fs pump pulses at the wavelength of 1300 nm. [ABSTRACT FROM AUTHOR]