Nonlinear Optical Devices Research Articles

Low threshold amplified spontaneous emission in ultrastable CsPbBr3-TS-1 nanocomposite films under two-photon excitation

Perovskite nanomaterials have attracted significant attention in the field of nanoscale laser field, however, poor environmental stability is the biggest challenge that restricts their applications. In this study, an in situ synthesis method was used to encapsulate CsPbBr3 nanocrystals (NCs) in titanium silicalite molecular sieve (TS-1). Owing to the hollow structure and the hydrophobicity of the TS-1, the hydro and thermal stabilities of the perovskite NCs were significantly improved. Using AB glue, we prepared thin films using a one-step spin coating method, and synthesized highly compact and smooth CsPbBr3 nanocomposite thin films. Amplified spontaneous emission (ASE) was achieved with a low-threshold under two-photon excitation at room temperature, and a stable emission under continuous intense laser shots in an ambient atmosphere was maintained. The influence of the perovskite concentration and calcination temperature on the ASE threshold was also investigated. This study will significantly broaden the application of perovskite nanocrystals in practical nonlinear optical devices.

Layered Metal‐Halide Perovskite Single‐Crystalline Microwire Arrays for Anisotropic Nonlinear Optics

AbstractHybrid organic–inorganic metal‐halide perovskites with diverse structure tunability are promising for nonlinear‐optical (NLO) applications, such as frequency conversion and electro‐optic modulation. For integrated NLO devices, single‐crystalline perovskite micro‐ and nanostructures with high quality and multifunctionality are in high demand. However, the fabrication of single‐crystalline perovskites arrays is still challenging in regulating liquid dynamics and crystal growth simultaneously. Herein, a capillary‐bridge‐manipulated strategy is established to steer the dewetting process of microdroplets and provide spatial confinement for crystal growth. These 1D perovskite microwire arrays show regulated geometry, pure orientation, and single crystallinity. Chiral ammonium molecules are introduced into the metal‐halide octahedral quantum wells to break the centrosymmetry of the perovskite, allowing the perovskite to exhibit excellent second‐order NLO properties. The as‐prepared microwire arrays also demonstrate linearly polarized second harmonic generation and two‐photon fluorescence. Microwire arrays exhibit higher second harmonic conversion efficiency compared with their polycrystalline thin‐film counterparts. It is believed that this strategy for the fabrication of chiral perovskite microstructure arrays holds great promise for NLO integrated applications and opens up an avenue to explore multifunctional chiral perovskites.

Controllable epitaxial growth of GeSe2 nanostructures and nonlinear optical properties

Germanium diselenide (GeSe2) has emerged as a new member of anisotropic two-dimensional (2D) materials and gained increasing attention because of its excellent air stability, wide band gap and unique anisotropic properties, which exhibits promising applications in the fields of electronics, optoelectronics and polarized photodetection. However, the controllable epitaxial growth of large-scale and high-quality GeSe2 nanostructures to date remains a big challenge. Herein, GeSe2 nanofilms with lateral size up to centimeter scale have been successfully prepared on mica substrate by employing chemical vapor deposition technique. Experimental results demonstrated that hydrogen is the key factor for the controllable growth of GeSe2 nanostructures and GeSe2-based heterostructures. Corresponding growth mechanism was proposed based on systematical characterizations. The nonlinear optical properties of as-prepared GeSe2 were investigated by employing open-aperture z-scan technique exhibiting significant saturable and reverse saturable absorption behaviors at wavelengths of 400 nm and 800 nm, respectively. This study provides a new and robust route for fabricating GeSe2 nanostructures and 2D heterostructures, which will benefit the development of GeSe2-based nonlinear optical and optoelectronic devices.

Influence of polarization, multi-valences and multi-coordination of cobalt: Third-order nonlinear, dielectric and Faraday properties of Bi0.5Co1.5S3/high optical basicity glass

In this study, we have successfully grown Co doped Bi0.5Co1.5S3 nanocrystals inside heavy metal oxide diamagnetic 42PbO-48TeO2-10B2O3 glass whose morphology, structure and properties were characterized using various techniques. The optimum parameters for Bi0.5Co1.5S3 nanocrystals formation is 380°C for 10hours. Glasses having different amounts of Bi0.5Co1.5S3presented colors from light yellow to green and pure blue due to the different optical absorption of Co2+ ions in octahedral and tetrahedral coordination units. X-ray diffraction pattern revealed the formation of orthorhombic Bi2S3 nanocrystals in glass and Raman spectra demonstrated modification on structure such as TeO4 → TeO3 and BO → NBO conversion. The red shift in transmission cutoff edge of glasses showed experimental evidence of quantum confinement effect. Due to the high optical basicity system, X-ray photoelectron spectra studies confirmed the co-existence of Co2+, Co3+ and Co4+ which presented characteristic absorption in ultraviolet-visible spectra. The introduction of Bi0.5Co1.5S3 greatly increased the polarizability of glass, resulting in significant improvement on third-order nonlinearity, AC conductivity and dielectric constant. 1% Bi0.5Co1.5S3 doped glass presents giant Verdet constant of 62 rad/T.m at 633nm, promising nonlinear refractive index (5.662 × 10−11 esu) and large dielectric constant (78). This result proved that the synthesis of multivalence states of Co doped Bi2S3 in glass is an efficient method to improve the optical, dielectric and magneto optical performance of glass. Such dilute magnetic semiconductor nanocrystals-glass system has great potential applications in nonlinear, dielectric and magneto optical current sensors and isolators devices.

Studying the surface morphology, linear and nonlinear optical properties of manganese (III) phthalocyanine chloride/FTO films

Scientific review of laser protective materials is currently primarily focused on improving linear transmittance and developing the optical limiting ability. Due to its unique large π electronic conjugated structure, phthalocyanine has become a successful optical limiting material. Thin films of manganese (III) phthalocyanine chloride (MnPcCl) were formed on FTO substrates using traditional thermal deposition techniques. The X-ray diffraction demonstrated that there is an amorphous structure for MnPcCl films. AFM's surface morphology shows that the MnPcCl film is homogeneous and formed by spherical and elliptical nanoparticles. The thickness dependences of both linear and nonlinear optical properties of MnPcCl films were also investigated via UV–Vis-IR measurements. The absorption coefficient examination indicated that the films were distinguished by an indirect transition with two energy gaps. The power of the He–Ne (633 nm) and green (533 nm) lasers were used to estimate optical limiting behavior. The MnPcCl film deposited on the FTO revealed a high optical laser limitation that could be acceptable for different nonlinear optical devices, like laser filters.

Nonlinear optical properties of CsPbClxBr3-x nanocrystals embedded glass

All-inorganic perovskite has attracted significant attention due to its excellent nonlinear optical characteristics. Stable and low-toxic perovskite materials have great application prospects in optoelectronic devices. Here, we study the nonlinear optical properties of CsPbCl x Br 3 − x ( x = 1 , 1.5, 2) nanocrystals (NCs) glass by open-aperture Z-scan. It is found that the two- (2PA) and three-photon absorption (3PA) intensity can be adjusted by the treatment temperature and the ratio of halide anions. The perovskite NCs glass treated at a high temperature has better crystallinity, resulting in stronger nonlinear absorption performance. In addition, the value of the 2PA parameter of CsPbCl 1.5 Br 1.5 NCs glasses decreases when the incident pump intensity increases, which is ascribed to the saturation of 2PA and population inversion. Finally, the research results show that the 2PA coefficient ( 0.127 cm GW − 1 ) and 3PA coefficient ( 1.21 × 10 − 5 cm 3 GW − 2 ) of CsPbCl 1 Br 2 NCs glass with high Br anion content are larger than those of CsPbCl 2 Br 1 and CsPbCl 1.5 Br 1.5 NCs glasses. This is mainly due to the greater influence of Br anions on the symmetry of the perovskite structure, which leads to the redistribution of delocalized electrons. The revealed adjustable nonlinear optical properties of perovskite NCs glass are essential for developing stable and high-performance nonlinear optical devices.

Submicron periodical poling by local switching in ion sliced lithium niobate thin films with a dielectric layer

Lithium niobate LiNbO3 (LN) on insulator wafers (LNOI) representing a submicron-thick LN film bonded to a SiO2 layer deposited on a thick LN substrate have been manufactured recently by ion slicing. Today, LNOI is one of the most promising materials for fabrication of various integrated optical devices, including waveguides, electro-optical modulators, and wavelength convertors, due to their high drop in refractive index at the interface between the film and the SiO2 layer. Creation of the stable domain structures with submicron periods in LNOI will improve the properties of nonlinear optical devices. Periodically poled LN with periods below 300 nm can be used to implement an optical parametric oscillator in the backward configuration. We have studied experimentally the ways to create the stripe domains and periodical domain structures in LNOI with a dielectric layer under the film by local switching. The identified scenarios of the domain evolution were attributed to the ineffective screening of depolarization field. We have shown that stripe domains and periodic domain structures can be produced by scanning with a biased tip only at temperatures above 80 °C. Periodical stable domain structures with periods down to 300 nm have been created.

A novel organic-inorganic ionic cocrystal - piperazine-1,4-diium tetrachloridocuprate(II) dihydrate delivering efficient optical limiting

The aqueous reaction of piperazine and copper chloride dihydrate yielded piperazine-1,4-diium tetrachloridocuprate(II) hydrate (PCu) cocrystal. Acid hydrolysis during pH optimization produced cationic piperazine-1,4-diium, which was neutralized by anionic tetrachloridocuprate(II) to form a stable ionic cocrystal. The PCu single crystal belongs to the space group C2/c of the monoclinic crystal system. High linear absorption with indirect bandgap and least possible crystal defects are coherently supported to the two-photon absorption assisted optical limiting phenomena in PCu cocrystal. The third order nonlinear refractive index (n2), absorption coefficient (β) and susceptibility (χ(3)) of title material are found to be (0.635±0.0058)×10-8 cm2W−1, (0.232±0.001)×10-4 cmW−1, (2.63±0.01)×10-6 esu respectively under continuous-wave laser (100 mW, 532 nm) excitation shows its suitability for nonlinear optical device applications. The variation in β measured at different nanosecond pulsed laser intensities confirmed the presence of sequential two-photon absorption. The noncovalent intermolecular charge transfer responsible for sequential two-photon absorption in PCu cocrystal is theoretically proved possible using DFT-UB3LYP/LANL2DZ+6-311G** level of quantum mechanical calculation. The onset optical limiting threshold values were measured to be (0.394±0.02)×1003 Wcm−2 and (1.62±0.02)×1012 Wm−2 for 100 mW continuous wave laser and 100 μJ nanosecond pulsed green laser (532 nm) irradiance respectively. Hence the PCu cocrystal can be a promising candidate for optofunctional applications.

Ultrafast third order nonlinear optical properties of self-assembled indium phthalocyanine multilayer films

An ultrathin composite films with alternated layers containing anionic lithium tetracarboxyl indium phthalocyanine chloride (ClInPc(COOLi)4) and cationic poly(diallydimethyl ammonium chloride) (PDDA) were prepared using layer-by-layer assembly technique. The resulting films were characterized by Ultraviolet-visible and Fourier transform infrared spectroscopy, showing regularly consecutive adsorption. The ultrafast third-order nonlinear optical properties of the films were investigated via a 4f coherent imaging system with phase object with 190 fs laser pulses at 532nm. The results demonstrate that the ultrathin films exhibited excellent self-focusing effect (n2 ∼ 8.86 × 10−17 m2/W) and reverse saturable absorption properties (β ∼ 5.19 × 10−10 m/W), while the nonlinear optical response of the same composite in aqueous solution were found to be negligible. Our results indicate that the ClInPc(COOLi)4/PDDA film is a promising candidate for future nonlinear optical devices.

Attaching azoles to Hantzsch 1,4-dihydropyridines: Synthesis, theoretical investigation of nonlinear optical properties, antimicrobial evaluation and molecular docking studies

In the present study, we designed three novel compounds via the combination of two precious nitrogen-containing scaffolds; 1,4-dihydropyridine (DHP) and azole, in the same molecule. To synthesize the title compounds, initially, azolyl benzaldehydes were obtained through the nucleophilic aromatic substitution reaction of 4-fluorobenzaldehyde with pyrazole, imidazole or 1,2,4-triazole. Subsequently, an unsymmetrical Hantzsch reaction was applied to achieve DHP scaffold, thus the target molecules. After structural characterization, the effects of various azole rings on optical and non-linear optical (NLO) properties were investigated by computational methods. Band gaps, chemical hardness/softness, dipole moments, average polarizability, first hyperpolarizability values were computed for the target compounds at the CAM-B3LYP/6-31++G(d,p) level of theory. The comparable results confirmed the potential of DHP-azole hybrids to be utilized in NLO devices. The title molecules were further tested for their antibacterial and antifungal activities following the evaluation of their drug likeness properties. The compounds containing imidazole or triazole rings represented better antifungal properties than antibacterial activities. Molecular docking studies were performed in the catalytic site of lanosterol 14α-demethylase, CYP51, from Candida albicans to explain the obtained biological results and suggest molecular modifications to endow this class of molecules with improved antifungal effects.

Highly Efficient and Robust Broadband Nano‐VO2(M) Saturable Absorber for Nonlinear Optics and Ultrafast Photonics

AbstractThe metal‐to‐insulator transition behavior and the fast and reversible phase transition behavior in vanadium dioxide (VO2) have attracted widespread attention to study various potential applications. However, few studies have been focused on its nonlinear properties and applications in the pulsed laser field. Here, the authors report the design and synthesis of monoclinic nano‐VO2(M) saturable absorber with broadband absorption which spans the entire near‐infrared region, and high optical nonlinearity which is much higher than those of carbon nanomaterials, gold nanocrystals, and Cu1.8S nanocrystals, as measured in the same condition. The nano‐VO2(M) optical modulators are integrated into the fiber laser cavities, and demonstrate wideband Q‐switching operations at 1, 1.56, and 2 µm and mode‐locking operation at 2 µm, with a pulse duration of 765 fs. This work first reveals the outstanding nonlinear optical properties of nano‐VO2(M) and lays a foundation for its development in advanced nonlinear optical and photonic devices.

Band Gap Engineering in Acceptor-Donor-Acceptor Boron Difluoride Formazanates.

π-Conjugated molecules with acceptor-donor-acceptor (A-D-A) electronic structures make up an important class of materials due to their tunable optoelectronic properties and applications in, for example, organic light-emitting diodes, nonlinear optical devices, and organic solar cells. The frontier molecular orbital energies, and thus band gaps, of these materials can be tuned by varying the donor and acceptor traits and π-electron counts of the structural components. Herein, we report the synthesis and characterization of a series of A-D-A compounds consisting of BF2 formazanates as electron acceptors bridged by a variety of π-conjugated donors. The results, which are supported by density functional theory calculations, demonstrate rational control of optoelectronic properties and the ability to tune the corresponding band gaps. The narrowest band gaps (EgOpt = 1.38 eV and EgCV = 1.21 eV) were observed when BF2 formazanates and benzodithiophene units were combined. This study provides significant insight into the band gap engineering of materials derived from BF2 formazanates and will inform their future development as semiconductors for use in organic electronics.

Antimicrobial activity of copper and silver metal nanoparticles synthesized from Riccia fluitans

Riccia bryophyte, a genus of liverworts that comes under the family of Ricciaceae, order Marchantiales. The plants are primitive plant structure, that's not differentiated into root, stem, and leaf. The material utilized in this study was a Spp of a Riccia fluitans, that grows on damp soil or, less unremarkably, floating in ponds, and is usually utilized in aquariums. The nanoparticles utilized in this study exhibit potential medicinal drug activity. Advantages of its therapeutic potential can be utilized in a sizable number of fields like health care, cosmetics, biomedical, food and feed, drug-gene delivery, surroundings, health mechanics, optics, chemical industries, physical science, area industries, energy science, catalysis, lightweight emitters, single lepton transistors, nonlinear optical devices, and photo-electrochemical applications. This study aimed to gauge the medicinal drug activity of Riccian nanoparticles, copper-loaded nanoparticles, and silver-loaded nanoparticles against varied microorganisms. The result of the study showed that the Nanoparticle, Ag-NP and Cu-Np synthesized from Riccia is having good antimicrobial activity against tested organisms.

Effect of 532 nm Nd:YAG laser irradiation on the optical properties of Ge1Se2.5 glass film

Ge1Se2 .5 alloy was prepared using the melt quenching method and the film was deposited by the thermal evaporation method. The as-prepared film was irradiated with Nd:YAG laser at 532 nm wavelength for different durations. The structural and morphological characterization indicates that the film has nanoparticles of different shapes with sizes varying from 80 to 300 nm and the structure becomes more crystalline on laser irradiation. The refractive index of the film increases, while the band gap decreases on laser irradiation. The dispersion behaviour of refractive index was studied using the WDD model. The decrease in band gap is attributed to the increase of laser-induced defects, which consequently narrows the energy gap. The non-linear optical parameters were found to increase with an increase in laser irradiation time. The increase in these parameters and transformation from the amorphous to the polycrystalline phase make laser-irradiated films suitable for non-linear optical devices and optical recording media.

Strong coupling of a plasmonic nanoparticle to a semiconductor nanowire

Abstract By placing a single Au nanoparticle on the surface of a cadmium sulfide (CdS) nanowire, we demonstrate strong coupling of localized surface plasmon resonance (LSPR) modes in the nanoparticle and whispering gallery modes (WGMs) in the nanowire. For a 50-nm-diameter Au-nanosphere particle, strong coupling occurs when the nanowire diameter is between 300 and 600 nm, with a mode splitting up to 80 meV. Using a temperature-induced spectral shift of the resonance wavelength, we also observe the anticrossing behavior in the strongly coupled system. In addition, since the Au nanosphere has spherical symmetry, the supported LSPR mode can be selectively coupled with transverse electric (TE) and transverse magnetic (TM) WGMs in the nanowire. The ultracompact strong-coupling system shown here may provide a versatile platform for studying hybrid “photon–plasmon” nanolasers, nonlinear optical devices, and nanosensors.

Tunable nonlinear optical responses of few-layer graphene through lithium intercalation

Abstract Intercalation has been demonstrated to be a powerful tool for tuning the physical and chemical properties of two-dimensional (2D) materials, providing the highest possible doping level and an ideal system to study various electronic states. In this work, we demonstrate that the nonlinear absorption effect of few-layer graphene (about 6–8 layers) is changed from saturable absorption (SA) to reverse saturable absorption (RSA) after lithium intercalation. This is attributed to the increase of Fermi energy owing to the charge transfer from Li to graphene layers in intercalated compounds (LiC6). And the change of nonlinear absorption effect is revisable after deintercalation. In addition, the modulation depth of RSA in lithiated graphene is found to rise with the decrease of incident laser wavelength, different from that of pristine graphene. Besides, the dispersion relationships of degenerate and nondegenerate two-photon absorption are analyzed from the results of nonlinear absorption and transient dynamics of lithiated graphene, indicating the 1.91–2.21 eV upshift of the Fermi surface. Our findings of the intercalation-tunable nonlinear optical absorption effect pave the way for the construction of nonlinear optical devices based on 2D intercalation compounds.

Enhanced nonlinear optical properties of the Cu2Se/RGO composites

Tuning the third-order nonlinear optical (NLO) properties of graphene (G) is of great significance in nonlinear optics. In this work, Cu2Se/reduced graphene oxide (RGO) composites with different Cu2Se contents were prepared via a solvothermal method. The structure and morphology indicated that the Cu2Se nanoparticles were uniformly dispersed on the surface of the graphene nanosheets. The NLO properties of the composites with different Cu2Se contents were investigated via the Z-scan technique with a picosecond-pulse laser at 532 nm. The results showed that the Cu2Se/RGO composites had the properties of reverse saturated absorption (RSA) and positive nonlinear refraction, and their NLO properties could be effectively regulated by controlling the Cu2Se contents. The third-order nonlinear susceptibility of the Cu2Se/RGO composite with a 1.5:1 mass ratio of Cu2Se to graphene oxide could reach 6.52 × 10−11 esu, which increased five-fold compared to G. The introduction of Cu2Se improved the NLO response of G, which might be attributed to the content effect of Cu2Se in the composites and the synergistic effects stemming from charge transfer between the Cu2Se and RGO This paper lays a foundation for the further study on the applications of the Cu2Se/RGO composite materials in NLO devices.

Parametric wavelength conversion with bidirectional utilization of a multiple QPM device.

A configuration for wavelength conversion and optical amplification by parametric interaction using a nonlinear optical device is proposed. It enables pump generation through second harmonic generation (SHG), difference frequency generation (DFG), and optical parametric amplification (OPA) using a multiple-quasi-phase-matched (M-QPM) LiNbO3 waveguide in a bidirectional manner. Wavelength conversion for the 1.4-1.6 µm band is experimentally demonstrated. In addition, it is demonstrated that the parametric gain band can be changed using various detunings between the pump and QPM wavelengths used for the DFG/OPA process. The proposed method would be useful for enabling high-capacity optical transmission outside the 1550-nm band.

Tuning the Electronic and Nonlinear Optical Properties of (4-Methylphenyl) (4-methylpiperidin-1-yl) Methanone and Its Substituted Analogues

A lot of molecules have been reported for certain applications. However, the need to continuously search for novel materials with more promise is very important because of the competitive technological innovations. One of the ways to achieve this is to use valid theoretical methods that can effectively and accurately predict the properties of existing molecular entities and using these methods to predict the properties of hypothetical molecules. The compound (4-methylphenyl) (4-methylpiperidin-1-yl) methanone (MPMPM) has been reported for its nonlinear optical potentials; however, investigating their reactivity indices would lead to the understanding of the mechanism behind their suitability as nonlinear optical devices. The molecular backbone of MPMPM was altered by introducing some substituents that could alter molecular properties. MPMPM and its derivatives were, therefore, optimized with density functional theory and the time-dependent density functional theory using pure and hybrid correlations and a polar basis set, 6-31G(d). The energy band gaps of the substituted derivatives were lower than that of MPMPM while the dipole moments and hyperpolarizabilities were higher, indicating that they could serve as better alternatives for nonlinear optical applications.

Electrical and Optical Properties of CNTs Additives Chalcogenide Glasses

Glasses have been used as the most versatile engineering materials for more than five decades. Chalcos is a Greek word which means ore former and glasses prepared by particular chalcogenide of group VI element of the periodic table or by their compounds have been known for more than 50 years as an optical material. The primary objective is to provide up to date description of the development in the field of optical and electrical properties of MWCNTs additive chalcogenide glasses. An extensive survey of relevant literature was carried out using sophisticated libraries, virtual media, different research laboratories, internet and also by personal contact with the senior researcher of this field. The exponential increase in D.C. conductivity was observed on increasing the CNT concentration. Inter nanotube connections increase which results in modification of chemical bond formation with increased CNT concentration. It has been observed that the optical band gap of CNT doped chalcogenide glass increases which may be attributed to the fact that CNT added to to the glasses retards the motion of charge carriers and may raise the optical bandgap. The electrical and optical properties of CNT additives chalcogenide glasses have been reviewed. Several applications based on CNT doped glasses have also been discussed, including the development of ionic memories, sensors, optical waveguides, holography, solid-state batteries, optical, and non-linear optical devices.