Nonlinear Optical Limiters Research Articles

Enhanced Nonlinear Optical Limiter in the Visible Spectral Region Based on Fe- and Co-Doped NiO Nanoparticles within PVP Nanofibers

Enhanced Nonlinear Optical Limiter in the Visible Spectral Region Based on Fe- and Co-Doped NiO Nanoparticles within PVP Nanofibers

Strong nonlinear optical limiting of resin composed by carbon nanotubes

The development of solid-state nonlinear optical limiting (NOL) materials is crucial for advancing the practicality in the field of optical limiting. In this paper, we innovatively prepare a new solid NOL material which is spiral carbon nanotubes doped epoxy resin (SCNTs-doped ER, SER) with a simple physical mixing method, and achieve an excellent nonlinear optical limiting performance. We experimentally measured optical limiting of SER with different SCNTs concentrations (0.14, 0.28, and 0.43 mg/mL) and obtained the nonlinear absorption coefficient, nonlinear refractive index, and third-order nonlinear susceptibility at the wavelength 1064 nm. Z-scan experiment results show that the SER exhibits a large nonlinear absorption coefficient (5.07 ± 0.38) × 10−9 m/W. We also measure the transmittance of the SER to evaluate its nonlinear optical limiting performance. For the SER with 0.43 mg/mL concentration, the linear transmittance and minimum transmittance with NOL effects at 1064 nm are 54.8% and 26.2%, respectively. In addition, the SER also has prominent features such as a high damage threshold and easy fabrication, indicating that the SER is a promising solid material for nonlinear optical limiting.

Nonlinear optical limiting based on polarizability inversion suspension

Nonlinear optical limiting (NOL) technology can protect human eyes and optical instruments from strong laser damage, but at the same time, it also reduces the transmission of weak signal light. Here we propose a NOL method based on polarizability inversion suspension with high transmittance (greater than 90%) under weak light. In the method, the light intensity-controlled polarizability inversion suspension is utilized to achieve NOL effect based on optical Kerr effect. The relationship between incident light intensity and transmittance in polarizability inversion suspension is achieved by analyzing the NOL mechanism and light forces acting on microspheres in suspension. In a proof-of-concept experiment, a PS (polystyrene)-CS2 suspension is used as the example suspension. We measure the optical limiting effect of PS-CS2 suspension at four different concentrations (3.45, 4.72, 5.82 and 6.80 g/L) and three different thicknesses (5, 10 and 20 mm) at the wavelength of 1064 nm. Among them, the 10 mm thick PS-CS2 dispersion with a concentration of 4.72 g/L has the best optical limiting effect with a large nonlinear optical limiting coefficient of 0.618, which is better than most NOL materials at 1064 nm. Therefore, the proposed method provides a new promising idea to achieve high-performance nonlinear optical limiting.

Reflective nonlinear optical limiter design based on coupled Tamm plasmon polaritons and optical Kerr effect

With the increasing applications of high-power lasers in fields such as laser fabrication, laser measurement, laser therapy and scientific research, there is an increasing demand for high-performance nonlinear optical limiters (NOLs) to protect human eyes and optical sensitive elements. Here we propose a brand-new approach to design a reflective NOL with an ultra-wide stop band based on coupled Tamm plasmon polaritons (TPPs) and optical Kerr effect. The NOL permits the transmission of weak signal light at the desired wavelength while effectively blocking potentially harmful or accidentally intense lasers at the same wavelength to avoid damage to sensitive optical elements or human eyes. The design can be optimized for the desired operating wavelength and threshold intensity by using different dielectric layers. In a proof-of-concept design, taking the 1064 nm laser as an example, we design a NOL capable of dynamically adjusting its transmission in response to laser intensity. The NOL has a high transmission of 85.21 % at weak light (intensity less than 0.20 MW/cm2), and the transmission can be rapidly reduced to 1.39 % when the incident light intensity increases to 60.37 MW/cm2. Furthermore, the broad stop band effectively safeguards the limiter from potential damage caused by intense light at different wavelengths. Our proposed limiter exhibits an exceptionally wide stop band range spanning from 0.5 ∼ 20 µm, nearly 30 times broader than conventional reflective NOLs. The proposed NOL design scheme provides a new promising method to design an excellent reflective NOL at the desired wavelength.

Fabrication of Two-Dimensional Homo-Bimetallic Porphyrin Framework Thin Films for Optimizing Nonlinear Optical Limiting.

Developing efficient metal-organic framework (MOF) optical devices with tunable third-order nonlinear optical (NLO) properties is an important challenge for scientific research and practical application. Herein, 2D monometallic and hetero/homo-bimetallic porphyrin MOF thin films (ZnTCPP(M) M = H2, Fe, Zn) were fabricated using the liquid-phase epitaxial (LPE) layer-by-layer (LBL) method to investigate the metal substitution dependent third-order NLO behavior. The prepared homo-bimetallic ZnTCPP(Zn) thin film exhibited enhanced third-order NLO performance with a higher third-order nonlinear susceptibility of ∼4.21 × 10-7 esu compared to monometallic and hetero-bimetallic counterparts. Additionally, theoretical calculations were performed to complement the experimental findings and revealed that the enhanced NLO effect of the ZnTCPP(Zn) thin film is mainly attributed to the enhanced local excitation. These findings not only provide a comprehensive understanding of the relationship between metal types and the NLO behavior of porphyrin MOF thin films but also offer valuable insights into the design and optimization of NLO devices.

Nonlinear optical studies of phenothiazine Schiff bases for optical limiting application

Synthesized Schiff-based organic molecules consisting of phenothiazine backbone (Phe-DNP, Phe-Ma, Phe-3) to investigate its optical limiting applications. The structural confirmation of compounds is carried out by FTIR and NMR spectroscopy. The quantum mechanical calculations of compounds are measured using Density functional theory (DFT) to investigate the electronic orientation in molecular orbitals and the theoretical bandgap. All the molecules show a broad absorption in the visible domain and the conjugated molecule absorption shifts towards the higher wavelength region. The effective intramolecular charge transfer of molecules in the order Phe-DNP> Phe-Ma>Phe-3 is understood from the ground state absorption spectra results. All the organic moieties exhibited sequential two-photon absorption upon studying the open aperture Z-scan technique. Phe-Ma molecule shows the highest nonlinear absorption (1.212× 10−10 m/W) and lowest optical limiting threshold (3.19 × 1012 W/m2) compared to other molecules suggesting that Phe-Ma could be a potential nonlinear optical limiter.

Phthalocyanine covalent frameworks doped in PMMA matrix as high performance nonlinear optical limiter

Phthalocyanine compounds are a class of macrocyclic conjugated structures with 18 π-electrons. And have better photophysical properties. However, the π-π electron interactions lead to aggregation between phthalocyanine molecules, which affects optical limiting properties. In this work, the conjugated organic small molecule antiphenylenediamine (PDA) is grafted onto the phthalocyanine conjugate system through the azo condensation reaction, and the covalent organic framework polymer (PDA-InPc) was obtained. Then it is doped into the polymethyl methylmethacrylate (PMMA) matrix to produce a phthalocyanine solid device with different thickness (PMMA-PDA-InPc). The aggregation-free phthalocyanine covalent organic frameworks avoids intramolecular aggregation of the phthalocyanine units, and dispersing it in PMMA solid devices can also reduce intermolecular π-π stacking. As a result, the fluorescence lifetime of PMMA-PDA-InPc is τ1 = 0.52 ns (A1 = 95.71%) and τ2 = 11.5 ns (A2 = 4.29%), indicating that the phthalocyanine conjugated unit exists mainly as monomers (95.71%), while the proportion as aggregates is very small (4.29%). At the input laser energy of 9 μJ, the nonlinear absorption coefficient of PMMA-PDA-InPc device is (2.2 × 10−9 m/W), which is significantly better than PMMA-InPc device (1.0 × 10−9 m/W), indicating that PMMA-PDA-InPc has improved nonlinear absorption and reverse saturation absorption. This design idea of non-aggregated phthalocyanine covalent organic frameworks and its solid device expands a new idea for the development of useable phthalocyanine optical limiters.

Nonlinear Optical Response of Dispersed Medium Based on Conjugates Single-Walled Carbon Nanotubes with Phthalocyanines

Nanosecond lasers have recently been widely involved in human activity. However, high-intensity laser radiation can cause severe damage to organs of vision and expensive photonic devices. Radiation in the near UV range is especially dangerous for human eyes, since it is strongly absorbed by biological media and is also invisible, i.e., the reaction time of the eye to such radiation is much lower than that of visible light. Passive limiters have high transmission (>70%) at a low light intensity and begin to “darken” only when the threshold value of the laser radiation intensity is reached. In this work, we studied liquid nanodispersed nonlinear optical limiters based on hybrids of single-walled carbon nanotubes (SWCNTs) with metal-free tetra(hydroxy)phthalocyanine (OH)4PcHH). The value of the hydrodynamic radius of separate particles after (OH)4PcHH binding increased from 288 ± 55 nm to 350 ± 60 nm, which confirms the attachment of phthalocyanine complexes to nanotubes. The third harmonic of a Nd:YAG nanosecond laser (355 nm, 20 ns) was used to study the nonlinear optical response. Based on a Z-scan with open-aperture and input-output dependence curves, third-order nonlinear optical absorption coefficients of 149, 236, and 229 cm/GW were obtained for dispersions of composites of SWCNTs and (OH)4PcHH in water, dimethylformamide (DMF), and dimethylsulfoxide (DMSO), respectively. Threshold values did not exceed 100 mJ/cm2. The Z-scan showed a gradual decrease in the duration of the laser pulse by 53%; however, near the focus, there was a sharp increase in the duration of the transmitted pulse, reaching a value of 29 ns in z = 0. This phenomenon confirms the occurrence of reverse saturable absorption in the investigated media and can be used in photonic devices to control the temporal characteristics of the signal. Thus, the possibility of protection of sensitive photonic devices and human eyes from nanosecond laser pulses in the near UV range by nanodispersed liquid media based on composites of SWCNTs with (OH)4PcHH has been discussed in this paper.

Coordination-Induced Symmetry Breaking on Metal-Porphyrinic Framework Thin Films for Enhanced Nonlinear Optical Limiting

Structural asymmetry affecting the nonlinear optics (NLO) of metal-organic frameworks (MOFs) is very important in fundamentals and applications but is still a challenge. Herein we develop a series of indium-porphyrinic framework (InTCPP) thin films and provide the first study on the coordination-induced symmetry breaking on their third-order NLO. The continuous and oriented InTCPP(H2) thin films were grown on quartz substrates and then postcoordinated with different cations (Fe2+ or Fe3+Cl-) in InTCPP(H2) (named InTCPP(Fe2+) and InTCPP(Fe3+Cl-)). The third-order NLO results reveal the Fe2+ and Fe3+Cl- coordinated InTCPP thin films have substantially enhanced NLO performance. Moreover, InTCPP(Fe3+Cl-) thin films cause symmetry breaking of microstructures, resulting in a 3-fold increase in the nonlinear absorption coefficient (up to 6.35 × 10-6 m/W) compared to InTCPP(Fe2+). This work not only develops a series of nonlinear optical MOF thin films but also provides new insight into symmetry breaking on MOFs for nonlinear optoelectronic applications.

Nonlinear optical limiting effect of porous graphene dispersions at 1064 nm.

This work presents a new, to the best of our knowledge, porous graphene dispersion in ethanol that can achieve a good nonlinear optical limiting (NOL) effect at the wavelength of 1064nm. Using the Z-scan system, the nonlinear absorption coefficient of the porous graphene dispersion with a concentration of 0.01mg/mL was measured as 9.69×10-9 c m/W. The NOL of the porous graphene dispersions in ethanol under three different concentrations (0.01, 0.02, and 0.03mg/mL) were measured. Among them, the 1-cm-thick porous graphene dispersion with a concentration of 0.01mg/mL has the best optical limiting effect, in which the linear transmittance is 76.7%, and the lowest transmittance is 24.9%. By using the pump-probe technique, we detected the formation and annihilation times of the scatter when the suspension interacts with the pump light. The analysis shows that the NOL mechanisms of the novel porous graphene dispersion are mainly nonlinear scattering and nonlinear absorption.

Dinuclear indium phthalocyanine doped in PMMA glass used as nonlinear optical limiter

A novel dinuclear indium phthalocyanine (In-Pc-In) is synthesized and doped in PMMA, the resulting In-Pc-In-PMMA can greatly suppress aggregation between Pc units. As a result, the In-Pc-In-PMMA show superior nonlinear absorption behaviors than the In-Pc-In-THF samples.

A Novel Nonlinear Optical Limiter Based on Stimulated Brillouin Scattering in Highly-Nonlinear Fiber

A novel nonlinear optical limiter (NOL) based on stimulated Brillouin scattering (SBS) in highly nonlinear fiber was proposed and experimentally demonstrated at 1550 nm wavelength. The nonlinear optical limiting effects of HNLF were characterized and demonstrated theoretically and experimentally. In a proof-of-concept experiment, we verified that the NOL based on a 50 m HNLF has excellent limiting performance due to its small effective area and high Brillouin gain coefficient. The linear transmittance and lowest nonlinear transmittance of the NOL were 87.5% and 11.9%, respectively.

Nonlinear Optical Limiting and Radiation Shielding Characteristics of Sm2O3 Doped Cadmium Sodium Lithium Borate Glasses.

Strong nonlinear absorption (NLA), reduced optical limiting (OL) thresholds, and high radiation shielding parameters are required for the effective use of glasses in the laser radiation and nuclear radiation protecting materials. In view of this, the efficacy of Sm2O3 on the nonlinear optical (NLO) and OL properties were ascertained (at 532 nm) along with radiation shielding characteristics. The open and closed aperture Z-scan profiles revealed the presence of positive NLA and nonlinear refraction (NLR) phenomena respectively. OL measurements showed the existence of limiting behavior in the studied glasses. The NLA and NLR coefficients were improved while the OL thresholds were decreased as the doping of Sm2O3 elevated to a higher doping level. These improvements in NLA, NLR coefficients and OL efficiencies were attributed to the non-bridging oxygens and high polarizable Sm3+ ions. The NLA and OL results clearly suggest the high (5 mol %) Sm2O3 doped glass (Sm5CNLB) glass is beneficial to protect the delicate devices and human eye by suppressing the high energy laser light. The theoretical linear attenuation coefficients (LAC) values of the presented SmxCNLB glasses were obtained with the help of Phy-X software between 0.284 and 1.333 MeV. At 0.284 MeV, the maximum values occur and take values between 0.302 (for Sm0CNLB) and 0.409 cm−1 (for Sm5CNLB). We found that the LAC for the presented SmxCNLB glasses is a function of Sm2O3 content, where the LAC tends to increase, corresponding to the high probabilities of interaction, as the content of Sm2O3 changes from 0 to 5 mol %. The effective atomic number (Zeff) for the presented SmxCNLB glasses was examined between 0.284 and 1.333 MeV. As the amount of Sm2O3 is added, the Zeff increases, and this was observed at any energy.

Nonlinear Optical Performance and Optical Limiting of Germanate Glasses Modified with Pbf2 and B2o3 Induced by Nanosecond Pulsed Laser

Nonlinear Optical Performance and Optical Limiting of Germanate Glasses Modified with Pbf2 and B2o3 Induced by Nanosecond Pulsed Laser

Oriented Assembly of 2D Metal-Pyridylporphyrinic Framework Films for Giant Nonlinear Optical Limiting.

The development of metal-organic frameworks (MOFs) with nonlinear optical (NLO) properties is of pronounced significance for optical devices. Herein, a series of 2D MOFs ZnTPyP(M) (TPyP = 5,10,15,20-tetrakis(4-pyridyl)porphyrin, M = Cu, Ni, Mn, H2) films with [010]-orientation growth composed of ultrathin nanosheets from a pyridylporphyrinic ligand are first obtained by using a liquid-phase epitaxial (LPE) layer-by-layer (lbl) growth approach. ZnTPyP(M) films show a giant nonlinear optical limiting (OL) response and can be modulated by tuning the type of metalloporphyrinic ligands. As a result, ZnTPyP(Cu) film exhibits the highest nonlinear absorption coefficient of 5.7 × 10-6 m/W compared to other reported NLO materials. Density functional theory calculations were consistent with the experimental results, revealing that the tunable π-π* local excitation and the increased delocalization of the metalloporphyrinic group regulate the NLO performance of ZnTPyP(M) films. These findings provide new insight into the effect of 2D porphyrinic MOFs toward the NLO response and offer new film candidates for nonlinear OL application.

Interpenetrated Metal-Porphyrinic Framework for Enhanced Nonlinear Optical Limiting.

Structural interpenetration in metal-organic frameworks (MOFs) significantly impacts on their properties and functionalities. However, understanding the interpenetration on third-order nonlinear optics (NLO) of MOFs have not been reported to date. Herein, we report two 3D porphyrinic MOFs, a 2-fold interpenetrated [Zn2(TPyP)(AC)2] (ZnTPyP-1) and a noninterpenetrated [Zn3(TPyP)(H2O)2(C2O4)2] (ZnTPyP-2), constructed from 5,10,15,20-tetra(4-pyridyl)porphyrin (TPyP(H2)) and Zn(NO3)2 (AC = acetate, C2O4 = oxalate). ZnTPyP-1 achieves excellent optical limiting (OL) performance with a giant nonlinear absorption coefficient (3.61 × 106 cm/GW) and large third-order susceptibility (7.73 × 10-7 esu), which is much better than ZnTPyP-2 and other reported OL materials. The corresponding MOFs nanosheets are dispersed into a polydimethylsiloxane (PDMS) matrix to form highly transparent and flexible MOFs/PDMS glasses for practical OL application. In addition, the OL response optimized by adjusting the MOFs concentration in the PDMS matrix and the type of metalloporphyrin are discussed in the ZnTPyP-1 system. The theoretical calculation confirmed that the abundant π-π interaction from porphyrinic groups in the interpenetrated framework increased the electron delocalization/transfer and boosted the OL performance. This study opens a new avenue to enhance OL performance by the construction of interpenetrated structures and provides a new approach for the preparation of transparent and flexible MOF composites in nonlinear optical applications.

Antimonene Prepared by Laser Irradiation Applied for Nonlinear Optical Limiting

Antimonene Prepared by Laser Irradiation Applied for Nonlinear Optical Limiting

Thermally Induced Phase Transition and Defect‐Assisted Nonlinear Absorption and Optical Limiting in Nanorod Morphology V2O5 Thin Films

Vanadium pentoxide (V2O5) thin films are greatly favorable materials for optoelectronic applications due to their broad optical bandgap and considerable thermal and chemical stability. Herein, the influence of thermal treatment on the microstructure related to the nonlinear optical, optical limiting, and phase transition behaviors of V2O5 thin films produced via ultrasonic spray deposition method onto FTO/glass substrates is systematically examined by Z‐scan experiments. Homogenous and crack‐free V2O5 thin films with nanorod morphology are obtained after thermal treatment. OA Z‐scan results indicate that the whole V2O5 thin films exhibit defect‐assisted nonlinear absorption behavior, and annealing at 450 °C increases the nonlinear absorption and optical limiting behavior. Higher annealing temperatures, in contrast, lead to a decrease in these behaviors. CA Z‐scan trace shows that the sign of nonlinear refractive index inverted by thermal process. The phase transition is associated with crystalline V2O5 thin films via thermal process. V2O5 thin films annealed at 450 °C are promising optical limiters within the 500–700 nm visible range due to their high linear transmittance (> 80%) and low optical limiting threshold.

Facile and environmentally friendly fabrication of few-layer bismuthene by electrochemical exfoliation method for ultrafast photonic applications

Bismuthene, an unique kind of two-dimensional material beyond graphene, has attracted considerable attention recently for its unique electronic and photonic properties. These unique properties render of Bismuthene as an excellent candidate for various applications, e.g., nonlinear optical limiters, optical switchers, and optical photonic devices. Toward this goal, we report herein an easy and quick alternative method to exfoliate a semi-metal Bi crystal to obtain few layer nanosheets in two different sizes based on electrochemical exfoliation approaches. At the different wavelengths and intensity, the resulting nonlinear optical activity is studied. The nonlinear absorption coefficient was calculated using Z-scan measurements. The exfoliated materials have been well characterized using various techniques, e.g., UV-Vis-NIR absorption, photoluminescence (PL), X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), Raman spectroscopy, transmission electron microscopy (TEM), and, XPS. The influence of different experimental conditions, such as the voltage on linear/nonlinear optical properties has been well examined. In addition, the mechanism of electrochemical cathodic exfoliation under different applied voltage in aqueous solution is described. This finding suggests that the bismuthene-based reverse saturable absorber RSA is a promising new material for broadband ultrafast optical limiters that protect against Vis-IR ultrashort pulse laser damage.

Energy Transmission of Vortex Beams Through 3rd Order Intensity Dependent Nonlinear Optical Limiters

Third order optical limiting utilizes nonlinear absorption or scatter to preferentially reduce the optical throughput of intense light through a medium. While these processes are dependent on intensity, it is often the transmitted energy or power that needs to be limited to avoid eye, sensor or detector damage. This is problematic when the input is a vortex mode or other higher order Gaussian distributions such as Bessel-Gaussian modes where the relationship between optical power and the on axis intensity is more complicated than for the TEM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">00</sub> Gaussian mode. Here we show that for higher order Bessel-Gaussian modes that beam power transmission is not equivalent to peak intensity transmission through intensity dependent absorption or scatter based optical limiters. We present a theoretical model and experimental data that demonstrates that the power throughput in these media, increases by 4 and 7 times for n = 1 and 2 Bessel-Gaussian modes, respectively, over that observed when a TEM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">00</sub> mode is used.