Strong Reverse Saturable Absorption Research Articles

Synthesis, structural, spectroscopic and theoretical insights into a new malononitrile derivative: A candidate for nonlinear optical applications

Functionalized alkylidene malononitriles play a crucial role as donor-acceptor molecules, exhibiting notable nonlinear optical (NLO) properties. Allylidene malononitriles, an analogue of alkylidene malononitriles, have not been explored before for their optical properties. The present work deals with the synthesis of (Z)-2-(3-(4-bromophenyl)-3-chloroallylidene) malononitrile using Knoevenagel condensation reaction of Z-3-(4-bromophenyl)-3-chloroacrylaldehyde and malononitrile. Structure of the compound was elucidated by single-crystal X-ray crystallography and related spectroscopic studies like FT-IR, NMR (1H, 13C), and UV-Vis spectroscopy, which were further supported with computational studies using Density Functional Theory (DFT) approach. The photoluminescence spectra showed that the compound exhibited an emission peak at 425 nm with an excitation wavelength of 352 nm. The single crystal study reveals that the compound belongs to a monoclinic system with space group P21/c. The thermal characteristics of the compound was analyzed using TGA-DTA/DSC. Investigation of the third-order nonlinear susceptibility was done by femtosecond Z-scan technique and demonstrated the potential of phenyl-substituted allylidene malononitriles for its nonlinear optical applications. The observed positive lensing and strong reverse saturable absorption (RSA) at both visible (532 nm) and Near IR (800 nm) regions make this compound a promising candidate for optoelectronic applications.

Nonlinear absorption and optical limiting performance of broad-band multi-branched aniline derivatives in the near-infrared region

A thorough investigation was conducted into the impact of π-linker and acceptor group modifications on the nonlinear absorption coefficient and optical limiting (OL) capabilities of multi-branched aniline derivatives. In the experiment, the femtosecond Z-scan technology and the OL experiment were used to detect the nonlinear optical (NLO) response of the samples dissolved in DMF solution at different wavelengths and energies. The femtosecond Z-scan experiments show that all samples exhibit reverse saturable absorption (RSA) caused by excited state absorption (ESA) induced by two-photon absorption (2PA) at specific wavelengths. NBTT still exhibits strong RSA properties at the near-infrared wavelengths, and the 2PA cross-section can reach 293 GM and 289 GM under the incident laser at the wavelength of 900 nm and 1030 nm, while maintaining strong two-photon-induced ESA. Furthermore, the femtosecond OL experiments reveal the commendable OL property of NBTT, and the limiting thresholds reach 0.0026 J/cm2 (at 800 nm) and 0.0033 J/cm2 (at 1030 nm). Quantum chemistry calculations utilizing density functional theory (DFT) show thatπ electrons contribute differently to the bond order on different branches of multi-branched molecules, and the value of Branch 1 is greater than or equal to that of the other two branches at the same position. This leads to the charge transfer (CT) of the molecules NBC and NBTC predominantly concentrated on Branch 1 during the 2PA process, while the addition of conjugate units and cyano-groups in the acceptor groups makes the CT of NBTT not only concentrated on Branch 1, but also extended to Branches 2 and 3. This research seeks to develop the structural design and practical application of multi-branched aniline derivatives to achieve high nonlinear absorption capacity, while maintain a low OL threshold in the near-infrared spectral range.

Ultrafast laser pulse repetition rate dependent switching of nonlinearity in water

Tailoring the nonlinear optical properties of materials through extrinsic parameter controls is advantageous for many applications. In this article, ultrafast laser pulse repetition rate induced switching of reverse saturable absorption to saturable absorption of water is reported. For the investigations, a conventional open aperture z-scan measurement system equipped with a variable repetition rate ultrafast laser source operating at the wavelength of 1030 nm was employed. A combination of weak saturable absorption and strong reverse saturable absorption induced by three-photon absorption is observed at low and moderate repetition rates. At repetition rates above 5 kHz, there is a significant variation in nonlinear absorption, where the reverse saturable absorption starts to diminish and saturable absorption increases. For repetition rates beyond 100 kHz, the nonlinearity gets reversed, where water tends to behave more like a saturable absorber with a weak three-photon absorption component.

Physicochemical and Nonlinear Optical Properties of a Stilbazolium Family Single Crystal with Third Order Nonlinear Optical Activity

AbstractA novel counter anion group was incorporated with the organic stilbazolium cation (C16H19N2+) to yield a new third‐harmonic‐generation‐active single crystal of 4‐[2‐(4‐dimethylamino‐phenyl)‐vinyl]‐1‐methyl‐pyridinium 2‐nitroaniline‐4‐sulfonate (DSNA). The slow evaporation solution growth technique is employed to obtain DSNA crystals, whose nonlinear responses are analysed through a continuous wave laser Z scan experiment. The thermally induced strong reverse saturation absorption and self‐defocusing behaviour of the DSNA crystal suggests that the material could be used as an optical limiting device. Optical characterization shows that the lower absorption edge falls in the visible region (530 nm), with a broad transparency range of 0.53 to 1 μm. Exploration of other optical constants, such as extinction coefficient (k=10−4), emission wavelength (602 nm – red light), optical (σopt=1010 Ωm−1) and electrical conductivity (σelc=1011 Ωm−1) also concludes that the DSNA crystal could be potentially employed in optoelectronic devices. The various bonds and their corresponding lengths and angles involved in the formation of DSNA ionic crystal are evaluated by means of single‐crystal X‐ray diffraction (SCXRD). Linear and nonlinear optical property findings undoubtedly affirm that the titular DSNA crystal is an effective nonlinear optical (NLO) crystal.

Exploring the nonlinear optical limiting activity of para-aminobenzoic acid by experimental and DFT approach

The present study accounts for the nonlinear optical behavior of para-aminobenzoic acid. The intramolecular charge transfer was established using electrostatic potential and Hirshfeld’s surfaces. The fingerprint plots identified that the bonds associated with the functional groups of para-aminobenzoic acid (amino and carboxyl) have major contributions to the total intramolecular charge transfer. It was observed that the para-aminobenzoic acid gave a broad absorption spectrum between 240 and 310 nm wavelength experimentally as well as computationally. From Tauc’s plot, the obtained direct band gap of para-aminobenzoic acid is 3.66 eV. The vibrational peaks of experimental FT-IR spectra were also found similar to the peaks observed in computational FT-IR. Moreover, high-frequency peaks were observed for the associated functional groups. The first-order hyperpolarizability of para-aminobenzoic acid was computed around 29.99 × 10–30 esu. We derived from the open-aperture Z-scan data that the para-aminobenzoic acid exhibits strong reverse saturable absorption. The positive value of the nonlinear absorption coefficient established the potential application of para-aminobenzoic acid in strong multi-photon absorption. Theoretical fit and intensity dependent Z-scan experiment confirm the occurrence of excited absorption (or) sequential two-photon absorption. The present study promises para-aminobenzoic acid for optical limiting applications.

Femtosecond nonlinear optical properties of polycyclic aromatic hydrocarbon-based Benzo[e]pyrene derivatives

We herein report our results on the nonlinear optical (NLO) properties of three polycyclic aromatic hydrocarbons (PAHs) based benzo[e]pyrene derivatives namely 10-phenylbenzo[e]pyrene (BP1), 13-fluoro-10-(4-fluorophenyl)benzo[e]pyrene (BP2), and 13-methoxy-10-(4 methoxyphenyl)benzo[e]pyrene (BP3). Using experimental techniques such as UV–Visible absorption, Z-scan technique, and theoretical time-dependent density functional theory (TDDFT), we have investigated the linear absorption, NLO coefficients, second hyperpolarizability, and optical limiting onset of these molecules. The ultrafast nonlinear Z-scan experiment was performed using ∼70 fs pulsed laser with 800 nm as central wavelength. Using the three-level model analysis based on rate equations, the contribution of different nonlinear processes contributing to nonlinear absorptions in these molecules is elucidated. All three molecules exhibited strong reverse saturable absorption due to mixed contribution of two-photon absorption (2PA) and three-photon absorption (3PA) with 2PA and 3PA coefficients of (1.26–1.79) × 10−11 cm/W and (6.23–7.39) × 10−5 cm3/GW2, respectively. The closed-aperture Z-scan data for all the examined molecules depicted valley-peak signature, which indicated a positive refractive index. The second hyperpolarizability was calculated with magnitude observed ∼10−32 esu. Using the TDDFT calculation, the complete optimization of the individual structure of molecules was achieved and the results matched with experimental observations.

Engineering the nonlinear optical properties of barium molybdate by doping Sn4+ ions for optical limiting device applications

Materials exhibiting strong two-photon absorption and low photo-damage threshold are highly desirable owing to their wide application in optoelectronic and photonic devices. Metal molybdates have gained significant attention for optoelectronic applications due to their excellent optical and luminescent properties. Herein, we report the nonlinear properties of the unexplored tin (Sn) doped barium molybdate (BaMoO4) nanostructures for tunable optical limiting applications. XRD and Raman Spectroscopy extensively studied structural properties. The UV–Vis absorption spectra clearly reveal the strong absorption in the blue region and suggest the bandgap reduction with increased Sn concentration in the host lattice. Open aperture Z scan mode, exhibits strong reverse saturable absorption owing to two-photon absorption. In addition, we observed that the nonlinear absorption coefficient and optical limiting threshold depend extensively on the excitation laser energy and can be altered by varying the concentration of Sn ions. The observed nonlinearity confirms that the synthesized Tin (Sn) doped Barium Molybdate (BaMoO4) nanostructures are potential for tunable optical limiting applications.

Defect-Dependent Nonlinear Absorption in the Lead-Free Double-Perovskite Cs2AgBiBr6

Lead-free perovskites have attracted increasing attention because they can address the toxicity and instability problems inherent to lead-halide perovskites. Furthermore, the nonlinear optical (NLO) properties of lead-free perovskites are rarely explored. Herein, we report significant NLO responses and defect-dependent NLO behavior of Cs2AgBiBr6. Specifically, a thin film of pristine Cs2AgBiBr6 exhibits strong reverse saturable absorption (RSA), while a film of Cs2AgBiBr6 with defects (denoted as Cs2AgBiBr6(D)) shows saturable absorption (SA). The nonlinear absorption coefficients are ca. 4.0 × 104 cm GW-1 (515 nm laser excitation) and 2.6 × 104 cm GW-1 (800 nm laser excitation) for Cs2AgBiBr6 and -2.0 × 104 cm GW-1 (515 nm laser excitation) and -7.1 × 103 cm GW-1 (800 nm laser excitation) for Cs2AgBiBr6(D). The optical limiting threshold of Cs2AgBiBr6 is 8.1 × 10-4 J cm-2 (515 nm laser excitation). The samples show excellent long-term performance stability in air. The RSA of pristine Cs2AgBiBr6 correlates with excited-state absorption (515 nm laser excitation) and excited-state absorption following two-photon absorption (800 nm laser excitation), while the defects in Cs2AgBiBr6(D) strengthen the ground-state depletion and Pauli blocking, resulting in SA.

Growth, characterizations and nonlinear optical studies of dimethylamine substituted anthracene chalcone single crystals

We report the structural, thermal, linear and nonlinear optical (NLO) properties of a newly grown anthracene based chalcone single crystal, (2E)-1-(anthracen-9-yl)-3-[4-(dimethylamino)phenyl]prop-2-en-1-one (abbreviated as DA-ANC). The chalcone was synthesized by Claisen-Schmidt condensation reaction and the single crystals were grown by slow evaporation of solution growth technique. Single-crystal XRD, NMR (1H & 13C), FT-IR, UV-Vis-NIR spectroscopies, TG/DTA, and computational DFT studies were performed to characterize the crystals. The intermolecular interactions were described by Hirshfeld surface analysis (HSA). The third-order NLO properties of DA-ANC were studied by Z-scan technique using CW-DPSS laser at 532 nm. Open aperture Z-scan exhibits strong two-photon assisted reverse saturation absorption (RSA) with two-photon absorption (TPA) coefficient (β) 6.9 × 10−5 cmW−1. Closed aperture Z-scan reveals the negative nonlinear refraction arising due to self-defocusing effect with nonlinear refractive index (n2) coefficient -1.31 × 10−8 cm2W−1. The optical limiting behavior based on TPA was performed and limiting-threshold was evaluated to be 6.47 kJ cm−2. The obtained one-photon and two-photon figures of merit satisfied the conditions of all-optical switching. The results show that DA-ANC can be a potential candidate for NLO applications.

Study of femtosecond nonlinear optical coefficients for Bi doped Se85-xTe15Bix chalcogenide thin films

The present work reports the influence of selenium replacement by bismuth on the nonlinear optical parameters of ternary Se85-xTe15Bix (x=0, 1, 2, 3, 4, 5 atomic %) chalcogenide thin films. Calculation of nonlinear refractive index (n2), two-photon absorption coefficient (β2) and third-order susceptibility (χ (3)) by well known Z-scan technique with femtosecond laser pulses were done. The Z-scan spectra for Se85-xTe15Bix upto Bi= 4 atomic % results in self- focusing behavior of n2 is positive while for Bi=5 atomic % n2 is negative. The behavior of n2 by using different physical parameters are exlpained. The comparison of experimental and theoretical values of n2 with pure silica are also studied. The presence of the valley at focus in open aperture Z-scan graph demonstrates strong reverse saturable absorption. The figure of merit (FOM) for the SeTe-Bi chalcogenide thin films is found to be less than 1 and are beneficial for all-optical switch devices.

Role of surface defects in the third order nonlinear optical properties of pristine NiO and Cr doped NiO nanostructures

Pristine NiO and 2% Cr doped NiO nanostructures are successfully synthesized by the modified auto–combustion method for the determination and improvement of linear and nonlinear optical behaviours, and for identifying them as suitable materials for optical limiting applications. Vibrational and linear optical properties of both nanostructures are investigated, and structural and morphological studies are carried out using XRD, FE-SEM, and HR-TEM. From the Kubelka-Munk model, the energy band gaps for pristine and doped samples are found to be 3.52 eV and 3.44 eV, respectively. Both pristine as well as Cr-doped NiO nanostructures reveal substantial nonlinear optical behaviour at the excitation wavelength of 532 nm, arising from the presence of strong reverse saturable absorption. The third order nonlinear absorption coefficients have values of the order of 10−10 m/W and 10−6 m/W, under pulsed (5 ns) and continuous wave laser excitations, respectively. These values confirm the suitability of these nanostructures for fabricating efficient optical limiting devices for safeguarding human eyes and optical sensors from hazardous laser radiation.

Enhanced and tunable femtosecond nonlinear optical properties of pure and nickel-doped zinc oxide films.

The nonlinear optical properties of pure ZnO and Ni-doped ZnO thin films are explored using the Z-scan technique at different input laser intensities and an excitation wavelength of 750 nm by 100 fs laser pulses. The pure ZnO and Ni-doped ZnO thin films were prepared by radio frequency magnetron sputtering at room temperature. A scanning electron microscope equipped with energy-dispersive x-ray spectroscopy was used to measure the thickness and composition of the thin films, while a UV-visible spectrophotometer was used to measure the linear optical properties. The structure of the thin films was measured using x-ray diffraction. Saturable absorption (SA) was observed in the pure ZnO thin film, while Ni-doped ZnO illustrated a combination of SA and reverse SA (RSA). The nonlinear absorption coefficient (β) and nonlinear refractive index (n2) of both pure ZnO and Ni-doped ZnO thin films were found to be input laser intensity dependent. As the input laser intensity increased, the nonlinear absorption coefficient and the nonlinear refractive index of both samples increased. An enhancement of two times in the nonlinear refractive index was observed for the Ni-doped ZnO thin film compared to the pure ZnO thin film. The optical limiting behavior of pure ZnO and Ni-doped ZnO thin films was investigated, and the data demonstrated that Ni-doped ZnO thin film is a good candidate for optical limiter applications due to the presence of strong RSA.

Femtosecond Third-Order Non-Linear Optical Properties of Unconstrained Green Fluorescence Protein Chromophores

We report herein results on the third-order non-linear optical (NLO) properties of four structurally unconstrained green fluorescence protein (GFP) chromophores, namely, 1, 2, 3, and 4. Using experimental techniques and theoretical calculations such as UV–visible spectroscopy, density functional theory (DFT), time-dependent density functional theory (TDDFT), and Z-scan techniques, we have investigated the linear absorption, ultrafast non-resonant third-order optical non-linearities, and the onset of optical-limiting thresholds of these benzylidenedimethylimidazolinone (BDI) dyes. The Z-scan measurements were performed at a wavelength of 800 nm with ∼70 femtosecond (fs) pulses. We have witnessed a strong reverse saturable absorption (fitted to three-photon absorption) for all of the molecules with fs pulse excitation. The valley–peak curves obtained from the closed-aperture Z-scan technique revealed the positive non-linear refractive index (self-focusing) nature of these molecules. We have evaluated the various third-order NLO coefficients (second hyperpolarizability, γ ∼10–33 esu), which were found to be larger than those of similar molecules reported in the recent literature.

The role of defects in the nonlinear optical absorption behavior of pristine and Co-doped V2O5 layered 2D nanostructures

V2O5 nanostructures doped with 1% Co have been successfully synthesized by simple hydrothermal method. Structural and morphological aspects, vibrational spectra and optical properties (linear and nonlinear) of pristine as well as Co-doped V2O5 (V2O5:Co) nanoparticles are investigated. X-ray diffraction patterns indicate that both V2O5 and Co doped V2O5 are stabilized in an orthorhombic structure. Energy band gaps measured using the Tauc plot give 2.24 eV for V2O5 and 2.16 eV for Co doped V2O5. When excited using 5 ns laser pulses at 532 nm in the open aperture Z-scan configuration, pristine as well as Co-doped V2O5 nanoparticles are found to show excellent nonlinear absorption, which arises from strong reverse saturable absorption occurring in the sample at this wavelength. The corresponding effective two-photon absorption coefficients are in the range of 10−11 to 10−12 m/W, and effective three-photon absorption coefficients are in the range of 10−22 to 10−23 m3/W2. When excited at the same wavelength using a continuous wave laser beam, the effective two-photon absorption coefficient gets enhanced to 10−6 m/W. These results confirm the suitability of V2O5 and Co-doped V2O5 nanoparticles for the fabrication of optical limiter devices for the protection of human eyes and sensitive optical detectors from hazardous laser radiation.

Enhanced nonlinear and thermo optical properties of laser synthesized surfactant-free Au-Pt bimetallic nanoparticles

The Au and Pt nanoparticles were synthesized employing laser ablation in water. Ligand-free Au-Pt bimetallic nanoparticles were generated by means of laser irradiation of the colloidal mixture of Au and Pt nanoparticles. The nonlinear optical characteristics like nonlinear absorption coefficient, nonlinear refractive index, optical limiting threshold and non linear optical susceptibility of Au, Pt, their colloidal mix and bimetallic nanoparticles were determined via Z scan method. All nanoparticle samples exhibited strong reverse saturable absorption behaviour with positive value of nonlinear absorption coefficient and strong optical limiting efficiency. The non linear absorption and refraction characteristics were found to be considerably enhanced for the Au-Pt bimetallic nanoparticles than the corresponding mono metallic nanoparticles and the pre-irradiation colloidal mix. The thermo optical features were also studied using thermal lens method and found to be tunable by controlling the fraction of Au and Pt in the bimetallic nanoparticles. To the best knowledge of the authors, it is presumed that, the present work is the first report on the non linear and thermo optical characterization of Au-Pt bimetallic nanoparticles. The present work has significance in nonlinear optical and photo thermal applications like optical limiting, photo thermal therapy and photo acoustic imaging.

Nonlinearly enhanced photoacoustic microscopy by picosecond-laser-pumped excited state absorption of phthalocyanine nanoprobes

Efficient nanoprobes with unique optical properties are highly desirable for good-performance photoacoustic (PA) molecular imaging. The conventionally used PA nanoprobes basically take their ground-state absorption with contrast to the indelible wideband background absorption as the imaging mechanism, thus severely limiting the imaging contrast and sensitivity in practical applications. Herein, a nonlinearly enhanced PA microscopy mechanism with suppressed background interference and improved brightness has been proposed, by distinctively exploiting the picosecond-laser-pumped excited state absorption of the tin phthalocyanine (SnPc) nanoprobes that exhibit strong reverse saturable absorption below the laser damage threshold of tissues. Both theoretical simulation and experimental investigation have been performed to verify the nonlinearly enhanced optical and PA properties of the SnPc nanoprobes with comparison to conventional PA contrast agents. The enhanced PA imaging capability of the SnPc nanoprobes with improved sensitivity and contrast has been demonstrated by tissue-mimicking phantoms and in vivo mouse models. This work revolutionizes the traditional contrast mechanism of PA nanoprobes by introducing picosecond-laser-pumped nonlinear optical nanomaterials, which prefigures great potential for biosensing and bioimaging with improved contrast and sensitivity.

Large Optical Nonlinearity of the Activated Carbon Nanoparticles Prepared by Laser Ablation.

Carbon nanoparticles (CNPs) with high porosity and great optical features can be used as a luminescent material. One year later, the same group investigated the NLO properties CNPs and boron-doped CNPs by 532 nm and 1064 nm laser excitations to uncover the underlying physical mechanisms in their NLO response. Hence, a facile approach, laser ablation technique, was employed for carbon nanoparticles (CNPs) synthesis from suspended activated carbon (AC). Morphological properties of the prepared CNPs were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). UV-Vis and fluorescence (FL) spectra were used to optical properties investigation of CNPs. The size distribution of nanoparticles was evaluated using dynamic light scattering (DLS). The nonlinear optical (NLO) coefficients of the synthesized CNPs were determined by the Z-scan method. As a result, strong reverse saturable absorption and self-defocusing effects were observed at the excitation wavelength of 442 nm laser irradiation. These effects were ascribed to the presence of delocalized π-electrons in AC CNPs. To the best of our knowledge, this is the first study investigating the NLO properties of the AC CNPs.

Twisted intramolecular motion arrested in aggregated state emission and the nonlinear optical properties of pyrene pyrazoline derivatives

Heterocyclic pyrene pyrazoline moieties containing similar structures but with differences in thiophene (PPT), furan (PPF) and pyridine (PPP) substitutions at the terminal molecules were synthesized. Their aggregation behaviour in THF-water mixtures was investigated and results demonstrated that PPT and PPP exhibited aggregation-induced emission (AIE), whereas PPF exhibited aggregation-induced blue-shifted emission (AIBSE). PPT and PPP provided red-shifted emission, while PPF had observed blue-shifted emission at high water fractions of 70-90%, confirming that aggregation effects played a major role in the molecular structure. Two emission peaks from locally excited and twisted intramolecular charge transfer confirmed the twisted nature from the dihedral angle values of the free reorganized molecules that were completely restricted in high water fractions due to molecular aggregation. This was further confirmed from colour Commission Internationale de l'Eclairage values as well as dynamic light scattering analysis. Third-order nonlinear optical properties were studied using a Nd:Yag laser beam Z-scan technique at 532 nm. The open aperture Z-scan revealed that PPT and PPF towards the peak point endured strong saturable absorption, whereas PPP indicated a strong reverse saturable absorption process. The AIE and AIBSE mechanisms from undergoing restricted twisting intramolecular motion in the aggregated luminogens provide great insight into new developments in AIEgen materials for these optoelectronic materials.

Optical limiting behavior of the natural dye extract from Indigofera Tinctoria leaves

In this work, we extract the natural dye ingredient found in Indigofera Tinctoria leaves, and investigate its nonlinear optical absorption by employing the Z-scan technique. The dye is extracted from Indigo powder which is commercially available for hair coloring applications. The powder, which is made by grinding Indigofera Tinctoria leaves into fine particles, is mixed with water, sonicated, centrifuged and filtered to give an optically clear extract. Linear absorption of the extract is measured in the visible spectral region using a spectrophotometer. Nonlinear absorption in the green spectral region is measured using 5 ns (5 × 10−9 s), 532 nm laser pulses obtained from a frequency-doubled Nd:YAG laser. The Indigofera Tinctoria dye is found to show excellent nonlinear absorption, which arises from strong reverse saturable absorption occurring in the sample at this wavelength. The third order nonlinear absorption coefficient, which is obtained by numerically fitting the Z-scan data to the nonlinear transmission equation, has a high value in the order of 10−10 m/W. This high nonlinear absorption, which is in the same range as that of materials such as graphene oxide, leads to an excellent optical limiting behavior, making Indigofera Tinctoria a potential candidate for fabricating optical limiter devices for eye and sensor protection.

Nonlinear optical absorption in PVA films doped by the novel natural dye extract from C. redflash leaves

In this work, we investigate the linear and nonlinear optical properties of polyvinyl alcohol (PVA) films doped by the natural dye extract from Caladium redflash (C. redflash) leaves. Linear optical properties of the doped films are tuned by varying the dopant concentration. Nonlinear absorption of the films is measured using 5 ns laser pulses at the wavelength of 532 nm, employing the open aperture Z-scan technique. The films show excellent optical limiting efficiency which arises from strong reverse saturable absorption at this wavelength, making them potential candidates for device applications in eye and sensor protection. These green, durable and cost-effective films can also be used as economical substitutes for costly transparent optical coatings made using synthetic dyes.